Ok, there seems to be some interest in this, so instead of writing to everyone that asked me "how to do it", I'd be better off writing it once and referring people to this thread.
What we're talking about here is a pretty basic concept, to put an item in color surrounded by a B&W picture. For an example of what I'm talking about, see Steve aka Nelson's thread.
To obtain this effect, open the image in Photoshop, create two copies of the background layer. To do so, open the "Layers" window (Menu: "Window > Layers", or press F7), take the small icon labeled "background" and drag it at the bottom of the Layers window on top of the icon that looks like a block note with the first page half folded. This will create a copy of your layer. Do this twice.
Next, select the top most layer, probably labeled "Background copy 2" by now. You need to transform this layer in B&W. To do so, follow the "transforming pictures in B&W channel mixer" article by Pierre Daniel posted on Phototakers, and then come back here for the next step.
Now you should have the top layer in B&W, the second layer in color, and the background also in color. You don't actually need the background, but I like to do things this way because it allows me to check with the original file anytime I need to. What we will do is make the background invisible, so in the Layers window click on the eye-shaped icon beside the layer "Background". Nothing dramatic will happen as this layer is under two other layers anyway, but we'll use this feature at the end of this procedure. For now, simply make sure that the background is invisible, while the two top most layers are visible (i.e. the eye-shaped icon is visible on these layers).
Ok, now comes the interesting part. What you want to do is create a mask into your top most (B&W) layer. A mask is an easy enough concept: when the mask is painted in white, the layer is visible, when it is painted in black, it's invisible, and when it is painted in any shade of grey, it will be semi transparent (in relation to the amount of black in your gray). So select the top most layer (the one in B&W) in your Layers window, and click on the small icon that looks like a grey square with a white circle in the middle, i.e. the second icon from the left at the bottom of the Layers window. This create a mask in your layer.
Now, make sure that you are working in the mask by clicking the white square that just appeared in your currently selected layer. This is important to remember: if you have a mask in a layer, you have to make sure that you select the right icon. The picture icon on the left represents the actual picture in the layer, while the white square is the mask. If you don't select the mask but instead start working on the picture, you will paint your picture in white or black, which is not what we want. Conversely, if you select the mask and try to adjust contrast, saturation, or pretty much anything, it won't work and you will wonder what goes wrong.
Once you are sure that the mask is selected, select a brush with a size you are comfortable working with (press "b" on your keyboard or select it from the tools window), select black as the foreground color in your tool window (you can press "x" on your keyboard to switch between black and white), and start drawing around and in the object that you want to appear in color in your B&W picture. By painting the mask in black, you effectively render this portion of the B&W image transparent, thus unmasking the colored image in the layer below. If at any time you make a mistake and want the B&W to appear again, switch to white, and paint this portion of the mask in white again. Voilà!
Once you are done and totally happy with the result, you want to merge the visible layers by going to the Layers menu and select "merge visible". Alternatively, you can press "command-shift-E" on a Mac or "control-shift-E" on a PC. This "flattens" the image into only two layers, the B&W and color composite, and the background. That's why I asked you to make the background invisible, so it would still be there after this last step. Now, make your background visible again (click the empty icon to make the eye appear), and you can compare the original with your artwork by making the top most layer invisible simply by clicking on the eye icon. If you're happy, you may decide to flatten this again to save disk space or not, up to you!
About the Author:
Cédric John was born in Switzerland, where he grew up before moving to Germany to pursue his studies. After graduating with a Ph.D. degree in Earth Sciences at the University of Potsdam, he moved to California where he currently works as an academic researcher. Cédric’s interest in photography started in 1997 with the acquisition of a Canon EOS 5 SLR camera, but was seriously boosted with the advent of affordable digital SLR cameras. His main photographic interest is nature, from macro to landscape, including wildlife photography.
Wednesday, June 6, 2007
How To Avoid Oversharpening Your Images
Sharpening is important. Pixels are arrayed in a grid, and if you capture a curve or a diagonal on a grid it will look like a staircase. It's like trying to draw the letter 'O' using the boxes of a tic tac toe game. Consequently many digital capture devices use anti-aliasing filters -- this is a fancy way of saying that the image is blurred slightly to avoid the jagged aliased appearance. Hence, curves and lines appear more natural.
This, of course, necessitates sharpening -- either on the computer or within the camera -- to give the image a nice crisp, sharp look. Most of us here realize the importance of sharpening. We have great tools at our disposal, including the Photoshop filters SmartSharpen, Unsharp Mask, and High Pass, as well as numerous third party plug-ins.
The difficulty lies in striking a good balance. How do you make a picture look sharp without oversharpening it? The explanation requires understanding how sharpening works. Sharpening tools recognize edges in an image. An edge occurs where adjacent pixels have different luminosity values -- in other words, one is brighter than its neighbor. A sharpening tool will identify the edge, then lighten half of the edge and darken the opposing side. This makes the edge transition look sharper, bolder, more visible. The intensity and size of the effect are variable, and determined by amount and radius settings in the sharpening filter used.
The problem is that when an object is sharpened too much the effect ceases to suggest sharpness. Rather, one can see a bright or dark 'halo' or outline around oversharpened objects. This uniformly detracts from the image, makes it look overprocessed, and can ruin a print!
Even more challenging is that not all edges are created equal. If you adjust your sharpening settings to bring out soft edges and subtle detail, then your bolder edges are sure to be oversharpened. By contrast, if you sharpen the boldest edges appropriately, you may end up undersharpening the subtler edges.
Oversharpening halos all along the rooftop. Here are my strategies to avoid oversharpening.
1. Sharpen ONLY when you've resized to the final output size (i.e. for print or web sharing). This does not include stylistic or regional sharpening that you do earlier in the workflow. But if you sharpen and THEN resize, even slightly, it will frequently look either unsharpened or oversharpened.
2. Sharpen on a separate layer. In other words, duplicate the background layer and sharpen the new layer. This allows you to vary the opacity of the sharpened layer. You can also do the following two fantastic and important steps:
- Separate the sharpening into Lighten and Darken layers. Take your duplicated, sharpened layer and duplicate it. So now you have two sharpened layers over your background. Set one to the blending mode 'Darken'. Set the other to the blending mode 'Lighten'. This separates the dark half of the sharpening process from the light half. You can turn on and off the dark and light halves separately to view their respective effects. I usually start by making 'lighten' invisible. I scan the image for areas with inappropriate black outlines or halos, and I decrease the opacity of the Darken layer until it looks better. Darken usually ends up between 70 and 100% opacity. Then reveal the Lighten layer. I usually keep Lighten between 30 and 50% opacity. This is a POWERFUL tool to take control of your sharpening.
- Use layer masks!! Say, for instance, that you take a picture of your friend at the beach, but your friend is sort of backlit and her face is in the shadow. You want to sharpen the face, but the problem is there is so much contrast between the face and the sky that you'll invariably oversharpen the outline of the head. No problem. Sharpen on a duplicate layer, then open up a layer mask. You should be seeing an oversharpened halo at this stage. Then create a layer mask (by clicking in Photoshop on the little icon that looks like a gray box with a white dot in it). Then take a soft black brush -- like 50 pixels in diameter, hardness of 20%, and opacity of 75%, and trace over the oversharpened area until the oversharpening disappears. * ideally, if you're following my advice about Lighten and Darken layers, you'll do this independently on each of the sharpened layers. * Now for those of you with Elements, who cannot use layer masks like this, you can do all of the above, but you may have to partially erase oversharpened areas (like with a soft, low opacity eraser) to undo the sharpening. It's not as reversible as a layer mask, but at least it's a second layer.
Two sharpened layers -- one set to Lighten and one set to Darken. Opacity is controlled independently for each layer, and layer masks are used to block out the most oversharpened edges.
For more advanced photoshoppers, consider switching to Lab color mode for this step. The reason is that in RGB the program is limited by a finite number of ways a pixel can be encoded. In Lab, the program can use millions of different 'theoretical' colors, mathematical but fictional colors in the process of sharpening. This allows it to default to a color other than black or white during heavy sharpening. When in Lab color I create a duplicate layer, go to the channels, and click on the Lightness channel. I sharpen that channel alone. Then I go to Image>Mode>RGB, opt to keep the layers (i.e. do not flatten), and voila! Now you can duplicate the sharpened layer again and split them to Lighten and Darken blending modes.
So now there's no excuse for a picture to be oversharpened! Remember, you want the mind and eye of the artist to speak through your pictures, but the visible hand of the Photoshopper should be left elsewhere.
About the Author:
I'm a 31 year old physician, specializing in infectious diseases and tropical medicine at Boston Children's Hospital and Harvard Medical School. I'm originally from Connecticut, but now live in Boston with my wife. My other hobbies are writing, music, hiking, and kayaking. I've travelled extensively internationally for work and study, and my interest in photography is a product of my travels. My Canon Rebel G accompanied me to 6 continents and 15 countries before I finally went digital last year. Much of what I know I've learned from my friends here at Phototakers. Visit Dr. Lantos images at http://drpablo.smugmug.com/
This, of course, necessitates sharpening -- either on the computer or within the camera -- to give the image a nice crisp, sharp look. Most of us here realize the importance of sharpening. We have great tools at our disposal, including the Photoshop filters SmartSharpen, Unsharp Mask, and High Pass, as well as numerous third party plug-ins.
The difficulty lies in striking a good balance. How do you make a picture look sharp without oversharpening it? The explanation requires understanding how sharpening works. Sharpening tools recognize edges in an image. An edge occurs where adjacent pixels have different luminosity values -- in other words, one is brighter than its neighbor. A sharpening tool will identify the edge, then lighten half of the edge and darken the opposing side. This makes the edge transition look sharper, bolder, more visible. The intensity and size of the effect are variable, and determined by amount and radius settings in the sharpening filter used.
The problem is that when an object is sharpened too much the effect ceases to suggest sharpness. Rather, one can see a bright or dark 'halo' or outline around oversharpened objects. This uniformly detracts from the image, makes it look overprocessed, and can ruin a print!
Even more challenging is that not all edges are created equal. If you adjust your sharpening settings to bring out soft edges and subtle detail, then your bolder edges are sure to be oversharpened. By contrast, if you sharpen the boldest edges appropriately, you may end up undersharpening the subtler edges.
Oversharpening halos all along the rooftop. Here are my strategies to avoid oversharpening.
1. Sharpen ONLY when you've resized to the final output size (i.e. for print or web sharing). This does not include stylistic or regional sharpening that you do earlier in the workflow. But if you sharpen and THEN resize, even slightly, it will frequently look either unsharpened or oversharpened.
2. Sharpen on a separate layer. In other words, duplicate the background layer and sharpen the new layer. This allows you to vary the opacity of the sharpened layer. You can also do the following two fantastic and important steps:
- Separate the sharpening into Lighten and Darken layers. Take your duplicated, sharpened layer and duplicate it. So now you have two sharpened layers over your background. Set one to the blending mode 'Darken'. Set the other to the blending mode 'Lighten'. This separates the dark half of the sharpening process from the light half. You can turn on and off the dark and light halves separately to view their respective effects. I usually start by making 'lighten' invisible. I scan the image for areas with inappropriate black outlines or halos, and I decrease the opacity of the Darken layer until it looks better. Darken usually ends up between 70 and 100% opacity. Then reveal the Lighten layer. I usually keep Lighten between 30 and 50% opacity. This is a POWERFUL tool to take control of your sharpening.
- Use layer masks!! Say, for instance, that you take a picture of your friend at the beach, but your friend is sort of backlit and her face is in the shadow. You want to sharpen the face, but the problem is there is so much contrast between the face and the sky that you'll invariably oversharpen the outline of the head. No problem. Sharpen on a duplicate layer, then open up a layer mask. You should be seeing an oversharpened halo at this stage. Then create a layer mask (by clicking in Photoshop on the little icon that looks like a gray box with a white dot in it). Then take a soft black brush -- like 50 pixels in diameter, hardness of 20%, and opacity of 75%, and trace over the oversharpened area until the oversharpening disappears. * ideally, if you're following my advice about Lighten and Darken layers, you'll do this independently on each of the sharpened layers. * Now for those of you with Elements, who cannot use layer masks like this, you can do all of the above, but you may have to partially erase oversharpened areas (like with a soft, low opacity eraser) to undo the sharpening. It's not as reversible as a layer mask, but at least it's a second layer.
Two sharpened layers -- one set to Lighten and one set to Darken. Opacity is controlled independently for each layer, and layer masks are used to block out the most oversharpened edges.
For more advanced photoshoppers, consider switching to Lab color mode for this step. The reason is that in RGB the program is limited by a finite number of ways a pixel can be encoded. In Lab, the program can use millions of different 'theoretical' colors, mathematical but fictional colors in the process of sharpening. This allows it to default to a color other than black or white during heavy sharpening. When in Lab color I create a duplicate layer, go to the channels, and click on the Lightness channel. I sharpen that channel alone. Then I go to Image>Mode>RGB, opt to keep the layers (i.e. do not flatten), and voila! Now you can duplicate the sharpened layer again and split them to Lighten and Darken blending modes.
So now there's no excuse for a picture to be oversharpened! Remember, you want the mind and eye of the artist to speak through your pictures, but the visible hand of the Photoshopper should be left elsewhere.
About the Author:
I'm a 31 year old physician, specializing in infectious diseases and tropical medicine at Boston Children's Hospital and Harvard Medical School. I'm originally from Connecticut, but now live in Boston with my wife. My other hobbies are writing, music, hiking, and kayaking. I've travelled extensively internationally for work and study, and my interest in photography is a product of my travels. My Canon Rebel G accompanied me to 6 continents and 15 countries before I finally went digital last year. Much of what I know I've learned from my friends here at Phototakers. Visit Dr. Lantos images at http://drpablo.smugmug.com/
How to selectively change parts of your image in photoshop
The ability to make complex and precise selections is required if one wants to differentially edit one's images. For example, if you have a photo of someone in the shade of a tree, but in front of a bright, sunlit landscape, the color cast on your subject will be quite different than that of the background. Making a global color adjustment could benefit one part of the image but hurt another.
Furthermore, making very precise selections allows you to combine differently edited versions of the same RAW image, or to combine a series of exposures that were bracketed for complex or high contrast lighting conditions.
Many have you have watched hours of your life trickling away as you struggled with the lasso, magnetic lasso, magic wand, and other selection tools. But can you really use these to select individual hairs or leaves?
Fortunately, for many images, the selection has already been made for you. It is merely incumbent upon you to extract them!
The principal we will employ in this tutorial is that of exploiting differences between different regions of a photo. This tutorial is geared towards those who use Adobe Photoshop, but it will certainly work in other programs. For those who use Photoshop Elements, I will provide some pointers that will allow you to perform similar techniques.
Now, we recognize an 'object' in a photo because it contrasts with its surroundings -- its color and lighting differ sufficiently from its surroundings that we recognize its shape. In order to select this object, we need to maximize these contrast relationships.
Here is a photo that I've recently taken of a baobab tree in Senegal. The tree is too dark, but if I adjust the curves or levels the sky becomes too bright. So I would like to perfectly select the tree so that I can modify the tree and the sky independently of one another. But believe me, there isn't time in my life to select the tree, complete with twigs and leaves, yet avoid selecting the little bits of sky, using Photoshop's selection tools.
To select the tree most easily and precisely, we need look at the Channels. In RGB images, there are three channels: Red, Green, and Blue. All are grayscale images, which, when combined, constitute a color image in the RGB color space. In the Red channel, objects that are very red appear light, objects very cyan (red's opposite) appear dark. In the Green channel green appears light and magenta appears dark. In the Blue channel blue appears light and yellow appears dark. Thus it is often predictable which channel will display the most contrast. Nonetheless, it is easy to go to the channels in Photoshop and see which one in which your subject is the most prominent.
There are other color spaces in Photoshop besides RGB. Lab color, for instance, uses three channels: Lightness, which contains all the tonal (light-dark) information in the picture, and two color channels. The a channel is a spectrum from green (negative) to magenta (positive), and the b channel is a spectrum from blue (negative) to yellow (positive). Neutral tones (shades of white and gray) occupy the midline of the a and b channel.
The CMYK channel is often used for printing, as it mimics the inks used on many printers: cyan, magenta, yellow, and black. It is a small color space, and generally not a good space to use for image editing. It can, however, be a good source of grayscale versions of your photo.
Below you can see all the various grayscale images that exist in the Photoshop color spaces. Once a useful channel is identified, you can make a duplicate of it and then play with curves and levels to increase its contrast, as illustrated in the b channel below.
I now copy this modified channel, go back to RGB, create a new channel, and paste it in. Important note: One can convert freely between RGB and Lab without loss of image quality. CMYK, however, is a much smaller color space, and you can throw away color information by switching to this color space. To avoid this, it may be useful to open a second copy of your image. Alternatively, use the Convert to Profile option instead if Image>Mode>CMYK or RGB, to best preserve the appearance of your original image. In order to combine the nice tree selection with the new channel, separating it from the ground, I paste them on top of the image as new layers. I then lower the opacity of the blue layer to 50%, allowing me to see where the channels differ from one another. I then simply erase. There are other ways to do this using the calculations function, but this is beyond our scope today.
Let's now go back to our first mask (the modified Blue channel), which will allow us to separate the tree and ground from the sky. I copy this channel to the clipboard. I then create two new curves adjustment layers. Adjustment layers (which can be used for curves, levels, hue/saturation, or several other functions) appear with a white box next to them, in which you can mask away the function from part of the image. Alt-clicking on the layer mask (this may be command-click on the Mac) opens up the layer mask, into which we can paste the mask of the tree. I paste it into both adjustment layers, and invert it on one of them. What I've done is create one layer that blocks out the sky (the sky is black and everything else white) and another that blocks out everything else. To smooth the transition between the different adjustment layers, I run a soft Gaussian blur on each of the masks. Because there is considerable fine detail, I run the blur at only 0.7 pixels. This nicely merges the transition between the adjustments and avoids unnatural appearing transitions. I can now modify the tree at will without fear of affecting the sky. When that's done I can fine tune the sky.
I now copy this modified channel, go back to RGB, create a new channel, and paste it in. Important note: One can convert freely between RGB and Lab without loss of image quality. CMYK, however, is a much smaller color space, and you can throw away color information by switching to this color space. To avoid this, it may be useful to open a second copy of your image. Alternatively, use the Convert to Profile option instead if Image>Mode>CMYK or RGB, to best preserve the appearance of your original image. In order to combine the nice tree selection with the new channel, separating it from the ground, I paste them on top of the image as new layers. I then lower the opacity of the blue layer to 50%, allowing me to see where the channels differ from one another. I then simply erase. There are other ways to do this using the calculations function, but this is beyond our scope today.
Let's now go back to our first mask (the modified Blue channel), which will allow us to separate the tree and ground from the sky. I copy this channel to the clipboard. I then create two new curves adjustment layers. Adjustment layers (which can be used for curves, levels, hue/saturation, or several other functions) appear with a white box next to them, in which you can mask away the function from part of the image. Alt-clicking on the layer mask (this may be command-click on the Mac) opens up the layer mask, into which we can paste the mask of the tree. I paste it into both adjustment layers, and [b]invert[/b] it on one of them. What I've done is create one layer that blocks out the sky (the sky is black and everything else white) and another that blocks out everything else. To smooth the transition between the different adjustment layers, I run a soft Gaussian blur on each of the masks. Because there is considerable fine detail, I run the blur at only 0.7 pixels. This nicely merges the transition between the adjustments and avoids unnatural appearing transitions. I can now modify the tree at will without fear of affecting the sky. When that's done I can fine tune the sky.
You can see that the final image is looks natural and was easy to do!
About the Author:
I'm a 31 year old physician, specializing in infectious diseases and tropical medicine at Boston Children's Hospital and Harvard Medical School. I'm originally from Connecticut, but now live in Boston with my wife. My other hobbies are writing, music, hiking, and kayaking. I've travelled extensively internationally for work and study, and my interest in photography is a product of my travels. My Canon Rebel G accompanied me to 6 continents and 15 countries before I finally went digital last year. Much of what I know I've learned from my friends here at Phototakers. Visit Dr. Lantos images at http://drpablo.smugmug.com/
Furthermore, making very precise selections allows you to combine differently edited versions of the same RAW image, or to combine a series of exposures that were bracketed for complex or high contrast lighting conditions.
Many have you have watched hours of your life trickling away as you struggled with the lasso, magnetic lasso, magic wand, and other selection tools. But can you really use these to select individual hairs or leaves?
Fortunately, for many images, the selection has already been made for you. It is merely incumbent upon you to extract them!
The principal we will employ in this tutorial is that of exploiting differences between different regions of a photo. This tutorial is geared towards those who use Adobe Photoshop, but it will certainly work in other programs. For those who use Photoshop Elements, I will provide some pointers that will allow you to perform similar techniques.
Now, we recognize an 'object' in a photo because it contrasts with its surroundings -- its color and lighting differ sufficiently from its surroundings that we recognize its shape. In order to select this object, we need to maximize these contrast relationships.
Here is a photo that I've recently taken of a baobab tree in Senegal. The tree is too dark, but if I adjust the curves or levels the sky becomes too bright. So I would like to perfectly select the tree so that I can modify the tree and the sky independently of one another. But believe me, there isn't time in my life to select the tree, complete with twigs and leaves, yet avoid selecting the little bits of sky, using Photoshop's selection tools.
To select the tree most easily and precisely, we need look at the Channels. In RGB images, there are three channels: Red, Green, and Blue. All are grayscale images, which, when combined, constitute a color image in the RGB color space. In the Red channel, objects that are very red appear light, objects very cyan (red's opposite) appear dark. In the Green channel green appears light and magenta appears dark. In the Blue channel blue appears light and yellow appears dark. Thus it is often predictable which channel will display the most contrast. Nonetheless, it is easy to go to the channels in Photoshop and see which one in which your subject is the most prominent.
There are other color spaces in Photoshop besides RGB. Lab color, for instance, uses three channels: Lightness, which contains all the tonal (light-dark) information in the picture, and two color channels. The a channel is a spectrum from green (negative) to magenta (positive), and the b channel is a spectrum from blue (negative) to yellow (positive). Neutral tones (shades of white and gray) occupy the midline of the a and b channel.
The CMYK channel is often used for printing, as it mimics the inks used on many printers: cyan, magenta, yellow, and black. It is a small color space, and generally not a good space to use for image editing. It can, however, be a good source of grayscale versions of your photo.
Below you can see all the various grayscale images that exist in the Photoshop color spaces. Once a useful channel is identified, you can make a duplicate of it and then play with curves and levels to increase its contrast, as illustrated in the b channel below.
I now copy this modified channel, go back to RGB, create a new channel, and paste it in. Important note: One can convert freely between RGB and Lab without loss of image quality. CMYK, however, is a much smaller color space, and you can throw away color information by switching to this color space. To avoid this, it may be useful to open a second copy of your image. Alternatively, use the Convert to Profile option instead if Image>Mode>CMYK or RGB, to best preserve the appearance of your original image. In order to combine the nice tree selection with the new channel, separating it from the ground, I paste them on top of the image as new layers. I then lower the opacity of the blue layer to 50%, allowing me to see where the channels differ from one another. I then simply erase. There are other ways to do this using the calculations function, but this is beyond our scope today.
Let's now go back to our first mask (the modified Blue channel), which will allow us to separate the tree and ground from the sky. I copy this channel to the clipboard. I then create two new curves adjustment layers. Adjustment layers (which can be used for curves, levels, hue/saturation, or several other functions) appear with a white box next to them, in which you can mask away the function from part of the image. Alt-clicking on the layer mask (this may be command-click on the Mac) opens up the layer mask, into which we can paste the mask of the tree. I paste it into both adjustment layers, and invert it on one of them. What I've done is create one layer that blocks out the sky (the sky is black and everything else white) and another that blocks out everything else. To smooth the transition between the different adjustment layers, I run a soft Gaussian blur on each of the masks. Because there is considerable fine detail, I run the blur at only 0.7 pixels. This nicely merges the transition between the adjustments and avoids unnatural appearing transitions. I can now modify the tree at will without fear of affecting the sky. When that's done I can fine tune the sky.
I now copy this modified channel, go back to RGB, create a new channel, and paste it in. Important note: One can convert freely between RGB and Lab without loss of image quality. CMYK, however, is a much smaller color space, and you can throw away color information by switching to this color space. To avoid this, it may be useful to open a second copy of your image. Alternatively, use the Convert to Profile option instead if Image>Mode>CMYK or RGB, to best preserve the appearance of your original image. In order to combine the nice tree selection with the new channel, separating it from the ground, I paste them on top of the image as new layers. I then lower the opacity of the blue layer to 50%, allowing me to see where the channels differ from one another. I then simply erase. There are other ways to do this using the calculations function, but this is beyond our scope today.
Let's now go back to our first mask (the modified Blue channel), which will allow us to separate the tree and ground from the sky. I copy this channel to the clipboard. I then create two new curves adjustment layers. Adjustment layers (which can be used for curves, levels, hue/saturation, or several other functions) appear with a white box next to them, in which you can mask away the function from part of the image. Alt-clicking on the layer mask (this may be command-click on the Mac) opens up the layer mask, into which we can paste the mask of the tree. I paste it into both adjustment layers, and [b]invert[/b] it on one of them. What I've done is create one layer that blocks out the sky (the sky is black and everything else white) and another that blocks out everything else. To smooth the transition between the different adjustment layers, I run a soft Gaussian blur on each of the masks. Because there is considerable fine detail, I run the blur at only 0.7 pixels. This nicely merges the transition between the adjustments and avoids unnatural appearing transitions. I can now modify the tree at will without fear of affecting the sky. When that's done I can fine tune the sky.
You can see that the final image is looks natural and was easy to do!
About the Author:
I'm a 31 year old physician, specializing in infectious diseases and tropical medicine at Boston Children's Hospital and Harvard Medical School. I'm originally from Connecticut, but now live in Boston with my wife. My other hobbies are writing, music, hiking, and kayaking. I've travelled extensively internationally for work and study, and my interest in photography is a product of my travels. My Canon Rebel G accompanied me to 6 continents and 15 countries before I finally went digital last year. Much of what I know I've learned from my friends here at Phototakers. Visit Dr. Lantos images at http://drpablo.smugmug.com/
Digital Single Lens Reflex Cameras, what makes them special
Some estimates for total digital camera sales during 2005 exceeded 80 million units. The growth is expected to be about 8 to 10% for 2006. There is one segment of the market, however, that is growing significantly faster. This segment is the digital single lens reflex, or dSLR for short, market. While estimates vary considerably, most agree that the segment will grow much faster than any other. The growth figures range between 25% & 50% growth for 2006.
It is clear to see in the PhotoTakers forums that the dSLR market is growing. More and more we see many questions with regards to which camera should be purchased. In order to help with this, I decided to put this article together, I hope it helps.
My intent here is to help people make an informed decision when looking at cameras. I will not give you recommendations on any particular brand, rather I will try to help you understand what certain features mean and how they will affect your photography. You will then be able to decide on which features you'd like in your camera. To avoid any misconceptions of quality based on brand names, I will categorize cameras based on a price range as opposed to names like "high-end", "pro" or "entry level".
Most of what I mention applies to film and digital SLRs. For the sake of clarity and ease, I will refrain from any discussion on film in this article. In essence film and digital sensors are just two different types of photosensitive materials.
Lastly, please understand that I cannot get into a great deal of detail on every comment. It suffices to say, that if you'd like clarification on any topic you can always ask in the forums and we will gladly clear it up.
Single Lens Reflex Cameras. What are they and what makes them special?
Single Lens Reflex (SLR) cameras are given their name because of the configuration they use. SLR's configuration uses a single lens that serves two roles. First the lens is used to compose and focus the image. Once the image is composed and focused, the photographer releases the shutter to record the image on the sensor through the very same lens. This dual role is accomplished by the use of a mirror within the camera. When the photographer composes and focuses the shot, the mirror reflects the image the lens produces up into the viewfinder. When the photo is taken the mirror is lifted out of the way so the shutter can expose the sensor.
The biggest advantage with using an single lens reflex digital camera is the ability of the photographer to see exactly what the sensor will see. The SLR allows you to confirm that focus, composition and depth of field will be correct. You are able to see what the sensor will see through your viewfinder. The second, and more commonly mentioned advantage of an single lens reflex camera, is the ability to change lenses to suit your needs. You are not limited to what the manufacturer decided to put on the camera. There are other factors that are usually ignored but should not be, I've outlined a few below.
* Viewfinder: Like I said, with the Digital SLR, you see what the sensor will see. This is actually very good because it gives you a brighter and clearer display than any electronic viewfinder can ever give you. Even if the P&S cameras have a separate viewfinder they are significantly smaller than the SLR and do not display any shooting data, typically.
* Sensor Size: All digital SLRs have relatively large sensors (physical dimensions, not pixel count) when compared to P&S cameras. Compared to the largest P&S sensors, the most common dSLR sensors have almost six times the area. This significantly increases image quality. The main reason for the increase in image quality is that noise is less of a problem on larger sensors. Another benefit of larger sensors is that shallow depths of field are more attainable. This makes it easier to get the blurred background effects. Ultimately, a P&S camera with a larger pixel count than an SLR will not produce as good an image as the SLR, from an overall point of view.
* Lens Quality & options: While the lens quality on today's P&S cameras are very good, the lens quality that is available for SLRs is usually superior. Of course there are exceptions to this, but in general, this is commonly the case. As mentioned above, the ability to change lenses is an advantage. This allows you to use purpose built lenses if you'd like. For example, in a P&S camera you might have a macro capability but with the dSLR you can attach a Macro lens. There is a significant difference in image quality.
* Shutter Lag: This is the time lag between the moment one presses the shutter and the moment the camera actually takes the photo. With SLR cameras this lag is basically non-existent. It is measured in millionths of a second. With P&S cameras, it can be rather long by comparison. It can cost you the ability to get the shot.
* Dynamic Range: This is the range of brightness levels that a device can capture. Simply put, it is the darkest to lightest levels of light where you can still see details in the printed image. In general, DSLR's have a greater dynamic range than do P&S cameras.
* RAW Formats: RAW formats (each manufacturer has their own standard) are image captures where the sensor data is saved without manipulation by the camera's internal software. This leads to the best quality image you can get from a digital camera. While some P&S cameras can capture in a RAW format, generally it is not the case. All dSLRs have the ability to capture RAW formats. While it is not something everybody will be concerned with, it is something that needs to be mentioned. JPG captures, by comparison, all are processed, to some extent, in camera and are compressed.
To be fair, there are disadvantages to dSLR cameras. First are the costs involved. The dSLR camera is much higher in price. This is especially true when one begins to add lens and accessory costs to the mix. Second is weight and bulk. They are simply larger. Again add optional lenses and accessories and this bulk increases. However, if the ultimate image quality is what you are after, then the dSLR is the way to get it.
About the Author:
Luis Valladares, operates a professional portrait studio out of the Miami Florida area. A member of the National Association of Professional photographers, Luis enjoys sharing his photographic knowledge with others.
It is clear to see in the PhotoTakers forums that the dSLR market is growing. More and more we see many questions with regards to which camera should be purchased. In order to help with this, I decided to put this article together, I hope it helps.
My intent here is to help people make an informed decision when looking at cameras. I will not give you recommendations on any particular brand, rather I will try to help you understand what certain features mean and how they will affect your photography. You will then be able to decide on which features you'd like in your camera. To avoid any misconceptions of quality based on brand names, I will categorize cameras based on a price range as opposed to names like "high-end", "pro" or "entry level".
Most of what I mention applies to film and digital SLRs. For the sake of clarity and ease, I will refrain from any discussion on film in this article. In essence film and digital sensors are just two different types of photosensitive materials.
Lastly, please understand that I cannot get into a great deal of detail on every comment. It suffices to say, that if you'd like clarification on any topic you can always ask in the forums and we will gladly clear it up.
Single Lens Reflex Cameras. What are they and what makes them special?
Single Lens Reflex (SLR) cameras are given their name because of the configuration they use. SLR's configuration uses a single lens that serves two roles. First the lens is used to compose and focus the image. Once the image is composed and focused, the photographer releases the shutter to record the image on the sensor through the very same lens. This dual role is accomplished by the use of a mirror within the camera. When the photographer composes and focuses the shot, the mirror reflects the image the lens produces up into the viewfinder. When the photo is taken the mirror is lifted out of the way so the shutter can expose the sensor.
The biggest advantage with using an single lens reflex digital camera is the ability of the photographer to see exactly what the sensor will see. The SLR allows you to confirm that focus, composition and depth of field will be correct. You are able to see what the sensor will see through your viewfinder. The second, and more commonly mentioned advantage of an single lens reflex camera, is the ability to change lenses to suit your needs. You are not limited to what the manufacturer decided to put on the camera. There are other factors that are usually ignored but should not be, I've outlined a few below.
* Viewfinder: Like I said, with the Digital SLR, you see what the sensor will see. This is actually very good because it gives you a brighter and clearer display than any electronic viewfinder can ever give you. Even if the P&S cameras have a separate viewfinder they are significantly smaller than the SLR and do not display any shooting data, typically.
* Sensor Size: All digital SLRs have relatively large sensors (physical dimensions, not pixel count) when compared to P&S cameras. Compared to the largest P&S sensors, the most common dSLR sensors have almost six times the area. This significantly increases image quality. The main reason for the increase in image quality is that noise is less of a problem on larger sensors. Another benefit of larger sensors is that shallow depths of field are more attainable. This makes it easier to get the blurred background effects. Ultimately, a P&S camera with a larger pixel count than an SLR will not produce as good an image as the SLR, from an overall point of view.
* Lens Quality & options: While the lens quality on today's P&S cameras are very good, the lens quality that is available for SLRs is usually superior. Of course there are exceptions to this, but in general, this is commonly the case. As mentioned above, the ability to change lenses is an advantage. This allows you to use purpose built lenses if you'd like. For example, in a P&S camera you might have a macro capability but with the dSLR you can attach a Macro lens. There is a significant difference in image quality.
* Shutter Lag: This is the time lag between the moment one presses the shutter and the moment the camera actually takes the photo. With SLR cameras this lag is basically non-existent. It is measured in millionths of a second. With P&S cameras, it can be rather long by comparison. It can cost you the ability to get the shot.
* Dynamic Range: This is the range of brightness levels that a device can capture. Simply put, it is the darkest to lightest levels of light where you can still see details in the printed image. In general, DSLR's have a greater dynamic range than do P&S cameras.
* RAW Formats: RAW formats (each manufacturer has their own standard) are image captures where the sensor data is saved without manipulation by the camera's internal software. This leads to the best quality image you can get from a digital camera. While some P&S cameras can capture in a RAW format, generally it is not the case. All dSLRs have the ability to capture RAW formats. While it is not something everybody will be concerned with, it is something that needs to be mentioned. JPG captures, by comparison, all are processed, to some extent, in camera and are compressed.
To be fair, there are disadvantages to dSLR cameras. First are the costs involved. The dSLR camera is much higher in price. This is especially true when one begins to add lens and accessory costs to the mix. Second is weight and bulk. They are simply larger. Again add optional lenses and accessories and this bulk increases. However, if the ultimate image quality is what you are after, then the dSLR is the way to get it.
About the Author:
Luis Valladares, operates a professional portrait studio out of the Miami Florida area. A member of the National Association of Professional photographers, Luis enjoys sharing his photographic knowledge with others.
Your digital cameras features and what they mean to you.
Price while obvious and not really a feature, it is worth mentioning for two reasons. First, it differentiates the cameras in this segment. Second, it is a significant investment.
With respect to the first point, many of the features listed here are available on many or all SLRs to some degree. However, realize that a $5,000 camera and a $1,000 camera cannot be compared head to head. The main reason is not the sensor. It is a range of details that come into play. Amongst those is build quality, convenience features, and performance/speed.
On the second point, since the price is high, it is not common for people to change dSLR cameras yearly. Your decision is one you will work with for some time. Spending a little time reading this can help.
Sensor Megapixels: This is the single most commonly quoted spec in a digital camera is the megapixel (MP) count. Unfortunately, because of the gross numbers involved (millions) much more is made of it than there should be. Surely you've heard it, "this camera has 2 million more pixels than that camera." If it were dollars we were talking about, fine, but in a digital image, it's just dots. In reality, when printed, the image from a 6MP camera is almost indistinguishable from that of an 8MP camera. The latter is only 10 to 12% larger on each side when printed. If you crop the image, for example to 8x10 or 5x7, you lose that. If you print on 8x10 or smaller, it makes no difference at all. It suffices to say that, in a given price range, today, the sensors from all dSLRs are about on par with one another.
Sensor Type: Sensors are available in two types today. CCD & CMOS. They are basically two different ways to make a photo sensitive digital device. Neither is clearly superior to the other. Each claims advantages over the other. The fact remains that both are widely used in today's digital market and both can meet the needs and demands of any digital photographer.
Sensor Size: Here we refer to the physical dimensions of the sensor and how it compares to the 35mm frame size. All dSLRs with the exception of two (as of 12/2005) use sensors that are smaller than a 35mm frame. Most of these have crop factors of 1.5x or 1.6x and some have a crop factor of 2x. Now that this has been mentioned, we should clear up a common misconception. The crop factor is sometimes referred to as a "lens multiplier" or a "focal length conversion". Regardless of the name, the smaller sensor does not change or add to the focal length of a lens. That is a physical characteristic of the lens. What is actually happening is that the sensor, since it is smaller than a 35mm frame, is cropping or ignoring the image edges that the lens produces. This makes it "seem" like a longer lens. Realize, however, that while this may be neat for the long lenses it is a problem for the wide angle lens. For more details on this, feel free to search the forums as it is beyond the scope of the article. So again here, all cameras in the sub $3,000 price range (as of 12/2005) have a crop factor and they are about equal.
ISO Sensitivity Range: The sensitivity of a digital sensor has been equated to the sensitivity ratings of film. This is actually quite good as it is a preset standard and it is something many are familiar with already. The International Organization for Standardization or as it is more commonly known, ISO, sets all sorts of international standards. The acronym "ISO" is derived from the Greek "Isos" or "equal". It is not an acronym for the name. As you can imagine, each country, based on language, would have a different acronym. So in the interest of "standardization" we get ISO as the worldwide acronym. ISO sets standards for photography in the film sensitivity area. The range of sensitivity that the camera can handle gives you an idea of the ability of the sensor to work in differing light. Most cameras have a good range. They start at ISO 100 or 200 and range up to ISO 1600 or higher. In general the lower the ISO rating the less noise (equivalent of film grain) you get in the image. The reality is that today's bodies have noise almost non-existent at or below ISO 400. All dSLRs start below ISO 400. The other side is the maximum. Again the higher the maximum the better, but in reality, most photographers rarely use ISO 1600 because the digital noise is obvious. However, to be fair, ISO 1600 film is also quite grainy. So, in short, most dSLRs have ample ISO range for the vast majority of photographers.
Image stabilization: While only one dSLR has image stabilization (IS) functionality built into the camera itself (as of 12/2005), it is worth mentioning. All other manufacturers put the IS capability into specific lenses. Image stabilization is a system that helps eliminate the problems associated with camera shake. This basically allows you to take pictures at slower shutter speeds and still get sharp results. This is helps a great deal with ambient light photography when not using a flash. Each manufacturer has its trademark name for IS, but the end result is similar, sharper pictures.
White Balance: All light has some color tonality to it and is categorized using a Kelvin (K) temperature scale. For example, sunlight has a different color tone than does florescent bulbs. Your eyes can adjust for the variations in the color of the light sources around you so that white is neutral, ie no color cast. Your camera cannot do this. That is where White Balance (WB) comes in. By setting the WB according to the light source, you can eliminate any color cast in your images. Most digital cameras today give you certain presets. Tungsten (common light bulb), florescent, sunlight and shade are common ones. Some cameras allow you to set a WB preset using a white subject or reference. Other cameras have the ability to set the K temperature to any K temperature value. Either one of these options gives you ultimate control and allows you to get accurate color in almost any light. To sum it up, common WB settings (sunlight, cloudy, shade, incandescent, etc) is good. Preset white balance using a reference, is better. Ability to select specific K WB temperatures is even better.
Minimum and Maximum Shutter Speeds: This refers to the fastest (shortest time) and slowest (longest time) shutter speeds the camera (or more precisely the shutter mechanism) can attain. These speeds are actually fractions of a second. So when you see 500 on the display it is referring to 1/500s. When looking at the maximum, the faster the shutter speed the better. The faster the shutter, the more likely you are to freeze any motion. However, in practice, one will rarely need anything near the maximum most dSLRs have today which is 1/4000s. In fact, you will find that in most cases you will usually be below 1/1000 or 1/2000 s. When looking at the minimum you will see full second amounts. In most cases it will be 30s followed by the term "bulb". The bulb setting is one that allows the photographer to shoot with exposures of any length. So long as the shutter release is held down, the camera will leave the shutter open. This is something that is used, most commonly, for night photography.
Built-in Flash: Most photographers, regardless of ability, are familiar with the idea behind the flash. A built in flash is very convenient. What many may not be aware of is how to differentiate one from another. The Guide Number (GN) for electronic flash defines its strength. This number allows you to calculate the maximum distance, for a given ISO sensitivity, that a flash can expose correctly. This GN is divided by the f-stop to get the distance. For example, if the GN is 80ft at ISO 100 then, at f/4, then the maximum distance you can be from the subject to properly illuminate it is 20ft. If you shot at f/10 it would be 8ft. If you take a great deal of photos that will require flash, and you do not plan on or like carrying a dedicated flash unit, then a built in flash is key. The higher the GN for the flash the better. However, be careful because not all GNs are equal. If the ISO quoted is not the same between two specifications then you need to apply some conversion. When the ISO sensitivity doubles, the GN changes by a factor of, approximately, 1.4. When the ISO is cut in half, the guide number changes by a factor of, approximately 0.7. For example, a GN of 100ft at ISO 100 is equal to a GN of 140ft at ISO 200 or a GN of 196ft at ISO 400.
External flash & Flash Sync: All dSLRs today have a hot shoe for mounting external or dedicated flash units. This typically sits above the lens on top of the viewfinder. These dedicated flash units vary in power and capability, but that is independent of the camera body. What is important is the maximum flash sync speed. Without getting into a huge amount of detail, this is the maximum shutter speed the camera can use that will permit synchronization with the flash unit. If you go above that speed, you run the risk of have one section of the frame darker than the others. With this, the higher the sync speed, the better. A good speed now is 1/180s and better would be 1/250s. Be aware, however, that some manufacturers say that there is no maximum, in other words it will sync at all speeds. This is usually only true when using their proprietary, current, flash technology. However, you should still consider the flash sync speed posted in the specs. One benefit to higher speeds is the better flexibility when using the flash as a fill light. This is done to lessen harsh shadows, for example. The faster the sync speed, the more useful the flash can be in fill situations when used outdoors. Another benefit is when shooting using other flash systems like studio flash units. The higher the shutter speed limit, the better you ability to lessen motion blur. This is particularly helpful when photographing children.
Depth of Field Preview: This is a feature most dSLRs have today. Few people use it. It is useful for letting you preview how the photo will look using the lens settings in place when you shoot the photo. When you press a button, the lens aperture is set to what it will be to take the photo. It will change the Depth of Field (DoF) you see in the viewfinder. Well some may ask doesn't the camera let you see this anyway? Isn't that the whole point of an SLR? Well yes and no. Yes the camera uses the actual photo lens to display the image in the viewfinder but it does it at the maximum aperture of the lens. That is done to keep the viewfinder as bright as possible which will aid in focusing and composition. The camera will shoot at the aperture that you or the camera determines to be necessary. The DoF button simply lets you check that the DoF is good by setting the lens' aperture to what it will be when you take the photo. With this, be certain the DoF preview is someplace that is comfortable for you to use. It is a really useful tool, when used.
Exposure modes: There are four common exposure modes most dSLRs have. They are Aperture priority, Shutter priority, Automatic and Manual modes. In the first three the camera's meter determines the proper exposure. How it is applied varies. In Aperture Priority mode, the photographer set the aperture they desire. The camera then sets the shutter speed to get the right exposure. In Shutter Priority mode, the photographer sets the shutter speed and the camera, in turn sets the aperture. In Automatic (Program) mode, the camera sets both shutter and aperture. The last mode, Manual, the photographer determines both shutter and aperture. In addition to these basic modes, there are certain options that some cameras have. They are quite helpful, particularly to beginning photographers. These typically include a Portraiture, Landscape, Sports and Macro mode. Some go into others like Night and/or indoor modes. What these do is basically "bias" the camera settings to get certain results. For example, Sports mode will keep the shutter speed as high as possible to freeze action. The Landscape mode will keep the aperture small (large number) to get more of the image in sharp focus. Eventually, if you have the inclination, you will likely bypass these, however, for casual quick shots where you do not want to set up a great deal these preset modes help a great deal.
Storage types: Compact Flash (CF) or Secure Digital (SD) are the two memory cards commonly in use today. For the most part, there is little difference in performance. The big difference right now seems to be capacity. The CF cards come in capacities as high as 8GB while SD cards max out at about 1GB. While this is a huge difference, most casual photographers will rarely use 1GB cards at this time. To give you an idea a 1GB card will fit over 350 8MP JPG images. This number of shots will likely more than enough for most. On the other hand, SD cards are smaller. The size difference is not really a big deal to most because most already feel CF cards are small enough.
Viewfinder Specs: These specs seem confusing and meaningless but should be looked at. Magnification, Eyepoint and Coverage are the three numbers you tend to see. Coverage is the percentage of the image that will be captured by the sensor visible in the viewfinder. In most dSLRs this is less than 100%. Again, most people ask "wasn't that the point of an SLR?" Yes but a 100% viewfinder is expensive to make. Hence they are usually found only in the top of the line cameras. The higher the coverage the easier it is to compose precisely. Magnification is how large the image in the viewfinder is when compared to the naked eye. This varies with the lens on the camera, however, most specs are based on using a 50mm lens. This is usually a number smaller than one. A 1x magnification would mean that the image in the viewfinder was just like looking at it with the naked eye. Again, here the higher the better, however, larger magnifications typically mean smaller coverage. The last is eyepoint. This is most critical for photographers with glasses. This refers to how far you can hold the camera from your eye and still see the whole images a data in the viewfinder. Here again, the larger the better. In general, the order of importance should be Coverage then Magnification and, lastly, Eyepoint. The only exception to this is with glasses. With those, Eyepoint becomes more important.
Viewfinder Information: This is the information displayed to the photographer when looking through the viewfinder. It is an important option to have and something that is easy for you to see and understand. Minimally you should see the following for the photo you are composing. Exposure Mode indicator, Focus Indicator, Shutter Speed, Aperture, Shot count or countdown, some sort of exposure meter, ISO sensitivity and a Flash Ready indicator. How the different manufacturers displays this will vary but they all include this. Some include some additional information. Ultimately how this is displayed is a matter of taste but make certain it is easy for you to understand or see.
LCD Size: Much is made about the size of the LCD on digital cameras. Don't get me wrong, having a good sized LCD is nice, but it is for reasons most don't consider. The biggest myth, "a bigger screen gives you better previews". I can't tell you how misleading this is. Even a 2.5" LCD is worthless as a display device to determine more than the most basic composition and the most obvious focus problems. The displays are simply not precise enough. The display on a dSLR is used to quickly review images for composition and basic lighting issues. For example, did you get everything in the shot? Are the shadows too strong? Was the subject completely blurred because of motion? etc. Another common use is to review the Histogram. This is simply a graph showing how the brightness of image is distributed. The last use is to set menu options or to perform common tasks like formatting cards etc. With all of these a larger display makes life easier.
USB and/or Firewire (IEEE 1394) ports: These are ports used to connect your camera to a computer or other device. The most common today is the USB port. The main issue to consider here is speed. USB has various standards and today's USB 2.0 is the faster option. If your computer has a USB 2.0 port, then this is something you can look for. Having said that, today, more and more users tend to have dedicated memory card readers on their computers. This makes the likelihood of connecting your camera to the computer smaller and thus USB connections on the cameras less necessary.
Metering Options: This refers to the most common metering methods. These are spot, center weighted and complete frame metering. Spot metering is the most precise of the options. In essence it determines exposure based on a spot you decide. This is usually less than 3% of the frame. Center weighted is the next most precise. It determines exposure by paying more attention to the center of the frame vs. the rest of the composition. The idea being your subject is there. The most general method is complete frame. This method takes the entire frame into account and determines exposure based on a set parameters. The last option has different names given to it by manufacturers but, ultimately, it is simply full frame metering.
Battery Type: This, today has come down to two options. They use Nickel Metal Hydride (NiMH) or Lithium Ion batteries. Currently most use the lithium cells. The big advantage is battery power and size. Lithium Ion batteries can be smaller and can accommodate high capacities. The downside to them is price. Lithium Ion batteries are more expensive which sometimes can be pricey if you plan on having second or third batteries.
Build: The build refers to how the body feels. Rigidity and balance are important. Better builds will take more every day use than lower quality builds. While weight is important for some users, realize this may come at the cost of sturdiness.
Dimensions & Weight: This is something that can come into play but has more to do with personal taste. For example, lighter bodies are great to carry but will feel awkward when you put a longer, heavier lens on the camera. Another example is dimensions. A larger camera body might be more comfortable for people with larger hands while a physically smaller package might be easier to handle for smaller hands. It is something to consider, however, the point is smaller and lighter is not always better.
AF System: This varies with each manufacturer. Many times you hear people refer to focus speed and this or that manufacturer having the fastest AF speed. Any AF system is good in the hands of a person that knows how to use his/her system. What differences may be important are focus sensor positions, number of sensors and AF options.
Image Formats: Three types of image formats have become mainstream in digital photography. Two of those are industry/computer standards. JPG (pronounced jay-peg) and TIFF are those two. The last is an image format that is proprietary to each manufacturer and those are RAW files. The two most common today in dSLRs are JPG and RAW. JPG files are compressed photographic files that are ready to go right out of the camera. They are "processed", so to say, by the camera. RAW files need to be translated first into something the PC can manipulate and then it is ready for output. In short, you process the RAW files. I feel most photographers are just fine working with JPG files. However many want the creative latitude offered by RAW files. Unfortunately this discussion is beyond the scope of this article. For the purposes of a camera choice, all dSLRs offer JPG and RAW files, so this will not be a decision point.
Ergonomics: This is a difficult on to cover but I mention it simply to bring it to your attention when purchasing a camera. With ergonomics I am referring to how easy the camera is to operate for you from a physical standpoint. For example, are the button sizes comfortable? Are the icons clear? Are the dials easy to access? Are the shooting parameters (aperture, shutter, ISO, etc.) easy to change? Are the buttons used to navigate menus comfortable? Is the grip comfortable? Is the shutter release in the right position? Unfortunately, in today's day and age, internet purchasing hampers the ability to "put your hands" on the camera so to say. So many times you have to rely on others. Ultimately, ask if that is your only option, however, if you can get your hands on a camera. Ultimately, this is something that you will be using for some time. The more comfortable it is, the more likely you are to use the camera.
Convenience Features: This is another commonly overlooked set of issues. With these I mean functionality that aids in the day-to-day use of the camera. For example, the histogram display which is a graphical representation of exposure. While all cameras have them they are displayed in different ways. Some are smaller than others, some are superimposed, etc. Some of the features that help in the day-to-day are: Automatic rotation of images that are shot vertically with the camera. The ability to zoom into the image on the LCD display is sometimes helpful to check focus. Custom setup storage to store common options help you by storing settings for differing conditions. LCD display of shooting data such as exposure settings helps you see what changes you can apply to get your desired effects. Highlight warning display tells you about potentially blown out highlights of the image.
Optional Accessories: I had to separate this out this way because options abound and it would be impractical to cover every single one. There are a multitude of accessories out there for cameras. For the case of this discussion, I will not consider a lens an accessory. What I will include are things like, battery expansion & vertical grip units, AC Adapters for the camera, remote control units and viewfinder accessories. Of course there are many others. These all provide advantages and more usability, however, some are quite pricey. Do some research, see if these options exist. Are they something you might use? For example, and battery expansion pack option allows for adding a second battery to the camera so as to extend battery life. In some cases they add a vertical shutter release. If you go to places where a second battery would help and you have limited access to power, this may be critical. You may want a vertical shutter release. In short, look into these options as well when making your decision.
About the Author:
Luis Valladares, operates a professional portrait studio out of the Miami Florida area. A member of the National Association of Professional photographers, Luis enjoys sharing his photographic knowledge with others.
With respect to the first point, many of the features listed here are available on many or all SLRs to some degree. However, realize that a $5,000 camera and a $1,000 camera cannot be compared head to head. The main reason is not the sensor. It is a range of details that come into play. Amongst those is build quality, convenience features, and performance/speed.
On the second point, since the price is high, it is not common for people to change dSLR cameras yearly. Your decision is one you will work with for some time. Spending a little time reading this can help.
Sensor Megapixels: This is the single most commonly quoted spec in a digital camera is the megapixel (MP) count. Unfortunately, because of the gross numbers involved (millions) much more is made of it than there should be. Surely you've heard it, "this camera has 2 million more pixels than that camera." If it were dollars we were talking about, fine, but in a digital image, it's just dots. In reality, when printed, the image from a 6MP camera is almost indistinguishable from that of an 8MP camera. The latter is only 10 to 12% larger on each side when printed. If you crop the image, for example to 8x10 or 5x7, you lose that. If you print on 8x10 or smaller, it makes no difference at all. It suffices to say that, in a given price range, today, the sensors from all dSLRs are about on par with one another.
Sensor Type: Sensors are available in two types today. CCD & CMOS. They are basically two different ways to make a photo sensitive digital device. Neither is clearly superior to the other. Each claims advantages over the other. The fact remains that both are widely used in today's digital market and both can meet the needs and demands of any digital photographer.
Sensor Size: Here we refer to the physical dimensions of the sensor and how it compares to the 35mm frame size. All dSLRs with the exception of two (as of 12/2005) use sensors that are smaller than a 35mm frame. Most of these have crop factors of 1.5x or 1.6x and some have a crop factor of 2x. Now that this has been mentioned, we should clear up a common misconception. The crop factor is sometimes referred to as a "lens multiplier" or a "focal length conversion". Regardless of the name, the smaller sensor does not change or add to the focal length of a lens. That is a physical characteristic of the lens. What is actually happening is that the sensor, since it is smaller than a 35mm frame, is cropping or ignoring the image edges that the lens produces. This makes it "seem" like a longer lens. Realize, however, that while this may be neat for the long lenses it is a problem for the wide angle lens. For more details on this, feel free to search the forums as it is beyond the scope of the article. So again here, all cameras in the sub $3,000 price range (as of 12/2005) have a crop factor and they are about equal.
ISO Sensitivity Range: The sensitivity of a digital sensor has been equated to the sensitivity ratings of film. This is actually quite good as it is a preset standard and it is something many are familiar with already. The International Organization for Standardization or as it is more commonly known, ISO, sets all sorts of international standards. The acronym "ISO" is derived from the Greek "Isos" or "equal". It is not an acronym for the name. As you can imagine, each country, based on language, would have a different acronym. So in the interest of "standardization" we get ISO as the worldwide acronym. ISO sets standards for photography in the film sensitivity area. The range of sensitivity that the camera can handle gives you an idea of the ability of the sensor to work in differing light. Most cameras have a good range. They start at ISO 100 or 200 and range up to ISO 1600 or higher. In general the lower the ISO rating the less noise (equivalent of film grain) you get in the image. The reality is that today's bodies have noise almost non-existent at or below ISO 400. All dSLRs start below ISO 400. The other side is the maximum. Again the higher the maximum the better, but in reality, most photographers rarely use ISO 1600 because the digital noise is obvious. However, to be fair, ISO 1600 film is also quite grainy. So, in short, most dSLRs have ample ISO range for the vast majority of photographers.
Image stabilization: While only one dSLR has image stabilization (IS) functionality built into the camera itself (as of 12/2005), it is worth mentioning. All other manufacturers put the IS capability into specific lenses. Image stabilization is a system that helps eliminate the problems associated with camera shake. This basically allows you to take pictures at slower shutter speeds and still get sharp results. This is helps a great deal with ambient light photography when not using a flash. Each manufacturer has its trademark name for IS, but the end result is similar, sharper pictures.
White Balance: All light has some color tonality to it and is categorized using a Kelvin (K) temperature scale. For example, sunlight has a different color tone than does florescent bulbs. Your eyes can adjust for the variations in the color of the light sources around you so that white is neutral, ie no color cast. Your camera cannot do this. That is where White Balance (WB) comes in. By setting the WB according to the light source, you can eliminate any color cast in your images. Most digital cameras today give you certain presets. Tungsten (common light bulb), florescent, sunlight and shade are common ones. Some cameras allow you to set a WB preset using a white subject or reference. Other cameras have the ability to set the K temperature to any K temperature value. Either one of these options gives you ultimate control and allows you to get accurate color in almost any light. To sum it up, common WB settings (sunlight, cloudy, shade, incandescent, etc) is good. Preset white balance using a reference, is better. Ability to select specific K WB temperatures is even better.
Minimum and Maximum Shutter Speeds: This refers to the fastest (shortest time) and slowest (longest time) shutter speeds the camera (or more precisely the shutter mechanism) can attain. These speeds are actually fractions of a second. So when you see 500 on the display it is referring to 1/500s. When looking at the maximum, the faster the shutter speed the better. The faster the shutter, the more likely you are to freeze any motion. However, in practice, one will rarely need anything near the maximum most dSLRs have today which is 1/4000s. In fact, you will find that in most cases you will usually be below 1/1000 or 1/2000 s. When looking at the minimum you will see full second amounts. In most cases it will be 30s followed by the term "bulb". The bulb setting is one that allows the photographer to shoot with exposures of any length. So long as the shutter release is held down, the camera will leave the shutter open. This is something that is used, most commonly, for night photography.
Built-in Flash: Most photographers, regardless of ability, are familiar with the idea behind the flash. A built in flash is very convenient. What many may not be aware of is how to differentiate one from another. The Guide Number (GN) for electronic flash defines its strength. This number allows you to calculate the maximum distance, for a given ISO sensitivity, that a flash can expose correctly. This GN is divided by the f-stop to get the distance. For example, if the GN is 80ft at ISO 100 then, at f/4, then the maximum distance you can be from the subject to properly illuminate it is 20ft. If you shot at f/10 it would be 8ft. If you take a great deal of photos that will require flash, and you do not plan on or like carrying a dedicated flash unit, then a built in flash is key. The higher the GN for the flash the better. However, be careful because not all GNs are equal. If the ISO quoted is not the same between two specifications then you need to apply some conversion. When the ISO sensitivity doubles, the GN changes by a factor of, approximately, 1.4. When the ISO is cut in half, the guide number changes by a factor of, approximately 0.7. For example, a GN of 100ft at ISO 100 is equal to a GN of 140ft at ISO 200 or a GN of 196ft at ISO 400.
External flash & Flash Sync: All dSLRs today have a hot shoe for mounting external or dedicated flash units. This typically sits above the lens on top of the viewfinder. These dedicated flash units vary in power and capability, but that is independent of the camera body. What is important is the maximum flash sync speed. Without getting into a huge amount of detail, this is the maximum shutter speed the camera can use that will permit synchronization with the flash unit. If you go above that speed, you run the risk of have one section of the frame darker than the others. With this, the higher the sync speed, the better. A good speed now is 1/180s and better would be 1/250s. Be aware, however, that some manufacturers say that there is no maximum, in other words it will sync at all speeds. This is usually only true when using their proprietary, current, flash technology. However, you should still consider the flash sync speed posted in the specs. One benefit to higher speeds is the better flexibility when using the flash as a fill light. This is done to lessen harsh shadows, for example. The faster the sync speed, the more useful the flash can be in fill situations when used outdoors. Another benefit is when shooting using other flash systems like studio flash units. The higher the shutter speed limit, the better you ability to lessen motion blur. This is particularly helpful when photographing children.
Depth of Field Preview: This is a feature most dSLRs have today. Few people use it. It is useful for letting you preview how the photo will look using the lens settings in place when you shoot the photo. When you press a button, the lens aperture is set to what it will be to take the photo. It will change the Depth of Field (DoF) you see in the viewfinder. Well some may ask doesn't the camera let you see this anyway? Isn't that the whole point of an SLR? Well yes and no. Yes the camera uses the actual photo lens to display the image in the viewfinder but it does it at the maximum aperture of the lens. That is done to keep the viewfinder as bright as possible which will aid in focusing and composition. The camera will shoot at the aperture that you or the camera determines to be necessary. The DoF button simply lets you check that the DoF is good by setting the lens' aperture to what it will be when you take the photo. With this, be certain the DoF preview is someplace that is comfortable for you to use. It is a really useful tool, when used.
Exposure modes: There are four common exposure modes most dSLRs have. They are Aperture priority, Shutter priority, Automatic and Manual modes. In the first three the camera's meter determines the proper exposure. How it is applied varies. In Aperture Priority mode, the photographer set the aperture they desire. The camera then sets the shutter speed to get the right exposure. In Shutter Priority mode, the photographer sets the shutter speed and the camera, in turn sets the aperture. In Automatic (Program) mode, the camera sets both shutter and aperture. The last mode, Manual, the photographer determines both shutter and aperture. In addition to these basic modes, there are certain options that some cameras have. They are quite helpful, particularly to beginning photographers. These typically include a Portraiture, Landscape, Sports and Macro mode. Some go into others like Night and/or indoor modes. What these do is basically "bias" the camera settings to get certain results. For example, Sports mode will keep the shutter speed as high as possible to freeze action. The Landscape mode will keep the aperture small (large number) to get more of the image in sharp focus. Eventually, if you have the inclination, you will likely bypass these, however, for casual quick shots where you do not want to set up a great deal these preset modes help a great deal.
Storage types: Compact Flash (CF) or Secure Digital (SD) are the two memory cards commonly in use today. For the most part, there is little difference in performance. The big difference right now seems to be capacity. The CF cards come in capacities as high as 8GB while SD cards max out at about 1GB. While this is a huge difference, most casual photographers will rarely use 1GB cards at this time. To give you an idea a 1GB card will fit over 350 8MP JPG images. This number of shots will likely more than enough for most. On the other hand, SD cards are smaller. The size difference is not really a big deal to most because most already feel CF cards are small enough.
Viewfinder Specs: These specs seem confusing and meaningless but should be looked at. Magnification, Eyepoint and Coverage are the three numbers you tend to see. Coverage is the percentage of the image that will be captured by the sensor visible in the viewfinder. In most dSLRs this is less than 100%. Again, most people ask "wasn't that the point of an SLR?" Yes but a 100% viewfinder is expensive to make. Hence they are usually found only in the top of the line cameras. The higher the coverage the easier it is to compose precisely. Magnification is how large the image in the viewfinder is when compared to the naked eye. This varies with the lens on the camera, however, most specs are based on using a 50mm lens. This is usually a number smaller than one. A 1x magnification would mean that the image in the viewfinder was just like looking at it with the naked eye. Again, here the higher the better, however, larger magnifications typically mean smaller coverage. The last is eyepoint. This is most critical for photographers with glasses. This refers to how far you can hold the camera from your eye and still see the whole images a data in the viewfinder. Here again, the larger the better. In general, the order of importance should be Coverage then Magnification and, lastly, Eyepoint. The only exception to this is with glasses. With those, Eyepoint becomes more important.
Viewfinder Information: This is the information displayed to the photographer when looking through the viewfinder. It is an important option to have and something that is easy for you to see and understand. Minimally you should see the following for the photo you are composing. Exposure Mode indicator, Focus Indicator, Shutter Speed, Aperture, Shot count or countdown, some sort of exposure meter, ISO sensitivity and a Flash Ready indicator. How the different manufacturers displays this will vary but they all include this. Some include some additional information. Ultimately how this is displayed is a matter of taste but make certain it is easy for you to understand or see.
LCD Size: Much is made about the size of the LCD on digital cameras. Don't get me wrong, having a good sized LCD is nice, but it is for reasons most don't consider. The biggest myth, "a bigger screen gives you better previews". I can't tell you how misleading this is. Even a 2.5" LCD is worthless as a display device to determine more than the most basic composition and the most obvious focus problems. The displays are simply not precise enough. The display on a dSLR is used to quickly review images for composition and basic lighting issues. For example, did you get everything in the shot? Are the shadows too strong? Was the subject completely blurred because of motion? etc. Another common use is to review the Histogram. This is simply a graph showing how the brightness of image is distributed. The last use is to set menu options or to perform common tasks like formatting cards etc. With all of these a larger display makes life easier.
USB and/or Firewire (IEEE 1394) ports: These are ports used to connect your camera to a computer or other device. The most common today is the USB port. The main issue to consider here is speed. USB has various standards and today's USB 2.0 is the faster option. If your computer has a USB 2.0 port, then this is something you can look for. Having said that, today, more and more users tend to have dedicated memory card readers on their computers. This makes the likelihood of connecting your camera to the computer smaller and thus USB connections on the cameras less necessary.
Metering Options: This refers to the most common metering methods. These are spot, center weighted and complete frame metering. Spot metering is the most precise of the options. In essence it determines exposure based on a spot you decide. This is usually less than 3% of the frame. Center weighted is the next most precise. It determines exposure by paying more attention to the center of the frame vs. the rest of the composition. The idea being your subject is there. The most general method is complete frame. This method takes the entire frame into account and determines exposure based on a set parameters. The last option has different names given to it by manufacturers but, ultimately, it is simply full frame metering.
Battery Type: This, today has come down to two options. They use Nickel Metal Hydride (NiMH) or Lithium Ion batteries. Currently most use the lithium cells. The big advantage is battery power and size. Lithium Ion batteries can be smaller and can accommodate high capacities. The downside to them is price. Lithium Ion batteries are more expensive which sometimes can be pricey if you plan on having second or third batteries.
Build: The build refers to how the body feels. Rigidity and balance are important. Better builds will take more every day use than lower quality builds. While weight is important for some users, realize this may come at the cost of sturdiness.
Dimensions & Weight: This is something that can come into play but has more to do with personal taste. For example, lighter bodies are great to carry but will feel awkward when you put a longer, heavier lens on the camera. Another example is dimensions. A larger camera body might be more comfortable for people with larger hands while a physically smaller package might be easier to handle for smaller hands. It is something to consider, however, the point is smaller and lighter is not always better.
AF System: This varies with each manufacturer. Many times you hear people refer to focus speed and this or that manufacturer having the fastest AF speed. Any AF system is good in the hands of a person that knows how to use his/her system. What differences may be important are focus sensor positions, number of sensors and AF options.
Image Formats: Three types of image formats have become mainstream in digital photography. Two of those are industry/computer standards. JPG (pronounced jay-peg) and TIFF are those two. The last is an image format that is proprietary to each manufacturer and those are RAW files. The two most common today in dSLRs are JPG and RAW. JPG files are compressed photographic files that are ready to go right out of the camera. They are "processed", so to say, by the camera. RAW files need to be translated first into something the PC can manipulate and then it is ready for output. In short, you process the RAW files. I feel most photographers are just fine working with JPG files. However many want the creative latitude offered by RAW files. Unfortunately this discussion is beyond the scope of this article. For the purposes of a camera choice, all dSLRs offer JPG and RAW files, so this will not be a decision point.
Ergonomics: This is a difficult on to cover but I mention it simply to bring it to your attention when purchasing a camera. With ergonomics I am referring to how easy the camera is to operate for you from a physical standpoint. For example, are the button sizes comfortable? Are the icons clear? Are the dials easy to access? Are the shooting parameters (aperture, shutter, ISO, etc.) easy to change? Are the buttons used to navigate menus comfortable? Is the grip comfortable? Is the shutter release in the right position? Unfortunately, in today's day and age, internet purchasing hampers the ability to "put your hands" on the camera so to say. So many times you have to rely on others. Ultimately, ask if that is your only option, however, if you can get your hands on a camera. Ultimately, this is something that you will be using for some time. The more comfortable it is, the more likely you are to use the camera.
Convenience Features: This is another commonly overlooked set of issues. With these I mean functionality that aids in the day-to-day use of the camera. For example, the histogram display which is a graphical representation of exposure. While all cameras have them they are displayed in different ways. Some are smaller than others, some are superimposed, etc. Some of the features that help in the day-to-day are: Automatic rotation of images that are shot vertically with the camera. The ability to zoom into the image on the LCD display is sometimes helpful to check focus. Custom setup storage to store common options help you by storing settings for differing conditions. LCD display of shooting data such as exposure settings helps you see what changes you can apply to get your desired effects. Highlight warning display tells you about potentially blown out highlights of the image.
Optional Accessories: I had to separate this out this way because options abound and it would be impractical to cover every single one. There are a multitude of accessories out there for cameras. For the case of this discussion, I will not consider a lens an accessory. What I will include are things like, battery expansion & vertical grip units, AC Adapters for the camera, remote control units and viewfinder accessories. Of course there are many others. These all provide advantages and more usability, however, some are quite pricey. Do some research, see if these options exist. Are they something you might use? For example, and battery expansion pack option allows for adding a second battery to the camera so as to extend battery life. In some cases they add a vertical shutter release. If you go to places where a second battery would help and you have limited access to power, this may be critical. You may want a vertical shutter release. In short, look into these options as well when making your decision.
About the Author:
Luis Valladares, operates a professional portrait studio out of the Miami Florida area. A member of the National Association of Professional photographers, Luis enjoys sharing his photographic knowledge with others.
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