Choosing Digital Camera Filters

Filters are those glass or gelatin disks or squares that are affixed to the front of your camera's lens, changing the light that passes through the lens in some way. Filters were really popular before the advent of digital photography because some of the effects you could get with them weren't possible (or easy) to achieve in the darkroom.

Glass and gelatin filters are less used today among casual photographers because you can achieve many of the effects they provide within Photoshop or other photo editing software. Yet, not all filtration effects are possible in the digital darkroom. Here's a description of the most essential filter add-ons:

• Infrared: Many digital SLR (single lens reflex) cameras are capable of taking photographs by using only infrared illumination, which produces a spectacular effect outdoors. You can get dark skies, vivid clouds, and ghostly white trees in your landscape shots and strange, pale complexions with your photographs of humans. However, you must buy an infrared filter that blocks visible light, and be prepared to shoot at slow shutter speeds (because very little light is left for the exposure). Also, you can't preview your shot because an SLR viewfinder turns black when an infrared filter is mounted.

• Polarizers: Polarizing filters, like the one shown in Figure 1, can reduce the glare bouncing off shiny surfaces in your photos. Simply attach the filter and rotate it until the glare disappears. These filters can also help deepen the contrast of the sky from certain angles.

Figure 1: Polarizing filters can reduce glare in many situations.

Be certain to buy a circular polarizer rather than a linear polarizer for your dSLR. (All polarizers are round; circular refers to the way in which the filter handles light.) Circular polarizers won't interfere with the autoexposure mechanism of your camera as linear polarizers can.

• Neutral density: The third kind of filter that every digital SLR photographer should own is a neutral density (ND) filter, so called because it blocks light but is neutral in color. ND filters come with various assigned filter factors, such as 2X (reduces the light by 1 f-stop), 4X (reduces light 2 f-stops) and 8X (cuts down 3 f-stops). As with most filters, they can be stacked to combine the effects of more than one, as long as the additional filters don't become visible in the image, thereby cutting off corners. Neutral density filters also come in a split variety - the top half (or bottom half or one side, if you rotate it) has neutral density, and the other half is clear.

You can do a lot of amazing things with a neutral density filter, including rendering objects invisible! All ND filters decrease the amount of light reaching the sensor, so you need to use a longer exposure than you would without the filter (or let your camera adjust the exposure for you automatically).

• Special Effects: Lots of different filters produce special effects, including star-like points on highlights, prisms, special colors, and so forth.

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Checking for Advanced Flash Features in Your Digital Camera

Most cameras have a built-in flash that operates in several modes. In addition to automatic mode, in which the camera gauges the available light and fires the flash if needed, you typically get the following options: fill flash, no flash, red-eye reduction, and night-time flash (also called slow-sync flash). Higher-end cameras may allow you to add an external flash unit as well.

Fill flash (or force flash)

This mode triggers the flash regardless of the light in the scene. Fill-flash mode is especially helpful for outdoor shots, such as the one in Figure 1. The image on the left was captured using auto-flash mode. Because the picture was taken on a sunny day, the camera didn't see the need for a flash. Switching to fill-flash mode and forcing the flash to fire threw some additional light on the subject's face, bringing her eyes into visible range.

Figure 1: Adding flash light brings the eyes out from the shadows created by the hat.

No flash

Choose this setting when you don't want to use the flash. For example, you may want to use this mode when you're shooting highly reflective objects, such as glass or metal, because the flash can cause blown highlights (areas that are completely white, with no tonal detail). You may also want to turn off the flash simply because the quality of the existing light is part of what makes the scene compelling, such as a burning candle.

When you turn off the flash, the camera may reduce the shutter speed to compensate for the dim lighting. That means that you need to hold the camera steady for a longer period of time to avoid blurry images. Use a tripod or otherwise brace the camera for best results.

Flash with red-eye reduction

Anyone who's taken people pictures with a point-and-shoot camera - digital or film - is familiar with the so-called red-eye problem. The flash reflects in the subject's eyes, and the result is a red glint in the eye. Red-eye reduction mode aims to thwart this phenomenon by firing a low-power flash before the "real" flash goes off or by lighting a little lamp for a second or two prior to capturing the image. The idea is that the prelight causes the iris of the eye to shut down a little, thereby lessening the chances of a reflection when the final flash goes off.

Unfortunately, red-eye reduction on digital cameras doesn't work much better than it does on film cameras. Often, you still wind up with fire in the eyes - hey, the manufacturer only promised to reduce red eye, not eliminate it, right? Worse, your subjects sometimes think the preflash or light is the real flash and start walking away just when the picture is actually being captured. So if you shoot with red-eye mode turned on, be sure to explain to your subjects what's going to happen.

Slow-sync flash

Slow-sync flash, which sometimes also goes by the name nighttime flash, increases the exposure time beyond what the camera normally sets for flash pictures.

With a normal flash, your main subject is illuminated, but background elements beyond the reach of the flash are dark, as in the top example in Figure 2. The longer exposure time provided by slow-sync flash allows more ambient light to enter the camera, resulting in a lighter background (the bottom example in Figure 2).

Figure 2: Slow-sync flash produces a brighter background than normal flash mode.

Whether a brighter background is desirable depends upon the subject and your artistic mood. However, remember that the slower shutter speed required for slow-sync flash can easily result in a blurred image; both camera and subject must remain absolutely still during the entire exposure to avoid that problem. In addition, colors in slow-sync pictures may appear slightly warmer because of white-balance issues.

External flash

Higher-end digital models may enable you to use a separate flash unit with your digital camera. In this mode, the camera's on-board flash is disabled, and you must set the correct exposure to work with your flash. This option is great for professionals and advanced photo hobbyists who have the expertise and equipment to use it; check your camera manual to find out what type of external flash works with your camera and how to connect the flash.

If your camera doesn't offer an accessory off-camera flash connection, you can get the benefits of an external flash by using so-called "slave" flash units. These small, self-contained, battery-operated flash units have built-in photo eyes that trigger the supplemental flash when the camera's flash goes off. If you're trying to photograph an event in a room that's dimly lit, you can put several slave units in different places. All the units fire when you take a picture anywhere in the room.

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Capturing a Great Digital Picture with Framing and Lighting

Good composition when capturing a digital photo is a little like good art. Even when people aren't consciously aware of all the components that go into great compositions, they still know what they like. That's because the very essence of composition is to arrange subject matter in a way that is both pleasing and which communicates the message the photographer is trying to get across. Framing and lighting are two elements of composing an image that can dramatically improve the quality of your images.

Framing images

Most kinds of photography benefit from building a visual frame around your subject, but architectural photos benefit more than most. If possible, frame your main subject by using doorways, windows, arches, the space between buildings, or the enveloping branches of trees as a pseudo border. Usually, these frames are in the foreground, which creates a feeling of depth, but if you're creative, you can find ways to use background objects to frame a composition.

When you're ready to shoot, keep some of these framing tips in mind:

• Use curves, lines, and shapes to guide the viewer's eye, as shown in Figure 1. In this case, the lines draw the eye to the center rock formation. Fences, gracefully curving seashores, meandering roads, railroad tracks, and receding tree lines all can lead the viewer through your carefully crafted composition.

Figure 1: Lines and shapes can guide your viewer through your photograph.

• Try to balance your compositions. Place interesting subject matter on both sides of the frame. If you pose a person on one side of the frame, include a building or some foliage on the other side to create a balanced look.

• Avoid splitting your photo in half with the horizon. Place the horizon one-third down from the top if you want to emphasize the foreground, or one-third up from the bottom if the background and sky are your most favored subjects.

• You don't have to compose landscapes in landscape mode. Try shooting some verticals. If you incorporate strong vertical lines, such as trees off to one side of the shot, your landscape photo can be naturally converted to a vertical orientation.

Using lighting techniques

You can make lots of improvements to a challenging subject simply by using good lighting techniques. Your uncle's bald head, a teenager's less-than-perfect complexion, a harshly lit beach scene, a drop of falling water - you can portray all these attractively with effective lighting techniques. In your uncle's case, throwing the top of his head in shadow and avoiding shiny lights can minimize glare. The teenager might benefit from diffuse lighting that softens the texture of his or her face. You can fix up that glaring direct sunlight on the beach by using a reflector to bounce light into the shadows. And you can freeze a drop of water in midair with a halo of light added by an electronic flash.

To use light effectively and take your photography to the next level, here are some tricks you'll want to master:

• Managing the quality of light: Light can be highly directional or soft and diffuse. It can cast sharp shadows and dot your subjects with specular highlights. Light comes in different colors, too. Figure 2 shows the kind of effect you can get with diffuse light.

Figure 2: Use diffuse light to soften an image.

• Using multiple lights: Photographers create some of the best pictures by using two, three, four, or more lights. One source can be used to illuminate the main part of your subject, and others can outline its edges, fill in the shadows, or call attention to a particular area. Some lighting arrangements are used often enough that they have their own names: broad lighting, rim lighting, Paramount lighting, and so forth.

If you can master applying multiple lights to model and shape the appearance of your subjects, you'll have a powerful tool at your disposal.

• Making best use of a light source's duration: Generally, electronic flash units are the main noncontinuous light source photographers put to work. Using the duration of the flash creatively requires practice and experience. Some techniques are simple. For example, you can use your flash's brief duration (particularly when shooting up close) to freeze even the fastest action. More complex is the use of repeating flashes to trace movement, or balancing flash output with ambient light to create combination exposures.

• Subtracting light: Sometimes, you don't want to add light to a scene as much as you want to remove it, to create a particular lighting effect or look. Barndoors are little flaps that look like a horse's blinders, and fit over an electronic flash or other light source to block the light or feather it onto a subject. Opaque sheets can block light coming from a particular direction, functioning as a sort of reverse reflector. Gadgets that stage lighting directors call cookies or gobos can change the size and shape of a beam of light. With lighting effects, sometimes less is more.

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Blurring the Backgrounds of Digital Photos to Enhance Motion

When photographing rapidly moving vehicles, the practice of using a high shutter speed goes right out the window. Sure, you freeze the action, but you also freeze everything else, including the rapidly rotating wheels and tires. The image you end up with looks like you took a picture of a parked vehicle. The solution is to use a slow shutter speed and pan with the subject.

1. Switch to shutter priority mode.
2. Choose a slow shutter speed of 1/60 second.
3. Pre-focus the camera on a subject that is equidistant to the point at which you will take the picture.
4. When the vehicle comes into view, center it in your view finder and begin panning the camera with the vehicle as outlined previously.

5. Press the shutter button fully when the vehicle reaches the desired position. Remember to continue panning after your press the shutter button. An image taken using this technique is shown next.

   

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Avoiding Red-Eye in Digital Photography

Red-eye occurs when light from the built-in flash of a camera bounces off the subject's retinas and reflects back to the camera lens. Along the way, the light takes on the tint of the blood vessels in the eye, which causes the eyes to appear to be glowing red in the picture. In animal pictures, eyes often have a white, yellow, or green glint.

Red-eye can result from any camera with a built-in flash, not just a digital camera. Why just a built-in flash? Because a built-in flash is positioned very close to the camera lens. When people look into the lens, they're also looking directly at the flash, which means that their retinas pick up and reflect almost all of the light from the flash. When you use an external flash head, you can position the flash farther from the lens and also angle the flash so that it's not aimed directly at the eyes.

Most digital cameras don't have connections for attaching an external flash head, unfortunately. Using a slave flash - a flash unit that is designed to work in tandem with a built-in flash - isn't always a solution, either, because your camera's built-in flash needs to fire to trigger the slave flash. If you stand at a distance from your subject, the built-in flash may be far enough away to prevent red-eye, but if you want to get a close-up, you're right back in red-eye zone. So what's the casual photographer to do?

A couple of tactics help reduce - but may not entirely eliminate - red-eye:

• Indoors, turn on as many lights as possible. In response to the additional light, your subject's eyes will constrict a little, so less flash light will be reflected back to the lens. (This is why you can usually use flash in the daytime without creating red-eye.) Most cameras also adjust flash output based on the ambient room lighting, so the brighter the setting, the weaker the flash needs to be.

• If you're shooting indoors during daylight, position your subjects next to a window. The daylight coming through the window will have the same effect as turning on additional room lights.

• Switch the flash to red-eye reduction mode. In red-eye reduction mode, the camera fires a brief, preflash light in advance of the main flash. The idea is the same as turning on lots of room lights - the eyes constrict in response to the preflash so that when the main flash fires, less light is reflected from the retinas. Keep in mind, though, that it's called red-eye reduction and not red-eye prevention mode for a reason: That little preflash can do only so much, so you may still wind up with some red-eye areas.

Be sure to warn your subjects to expect two bursts of light. Otherwise, they'll think that the preflash is the real flash and assume that they can quit smiling and get back to whatever they were doing before you pestered them for a picture. Some cameras actually emit three lights for each shot. The third beam, which the camera sends out when you depress the shutter button halfway, helps the camera's autofocusing mechanism pinpoint the subject-to-camera distance.

• Consider posing your subjects so that they're not looking directly into the camera lens. A profile shot can be every bit as captivating as a regular, face-forward image, as illustrated by Figure 1. You also can ask your subjects to look off to one side or slightly up or down. Because the flash light won't be heading straight for the eyes, red-eye reflections will be minimized.

Despite your best efforts though, some pictures will still be marred by the red-eye effect. The good news is that you can fix the problem easily in your photo editor.

Figure 1: Consider shooting subjects in profile to avoid red-eye in flash pictures.

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