So, to kick off this new column on digital photography, I'm going to address this "digital-vs.-film" question in the hopes that those of you who are still desperately clinging to that quaint, 19th-century, celluloid-based, analog imaging technology can at last put your digital camera fears to rest.
As Good as What?
As you may have already guessed, the opinion expressed herein is that digital is as good as film, but to really stand by that statement, I need to make a few clarifications. The tricky part about comparing the two is that the "film" end of the question is a little complicated.
If you're using medium-format or large-format film, a professional film lab, and a high-end $20,000 scanner run by a skilled operator, then yes, you'll be getting better results with film than you can expect from today's current crop of digital SLRs and prosumer digital cameras. (When you head into the world of high-end digital camera backs, things get more complicated, but that is a niche-ier market than we're going to deal with in this column.)
But when speaking of "film," most people are referring to shooting with a 35mm camera with a decent lens, having the film professionally processed, and then scanning the results on a reasonably priced ($500-$1,000) scanner, with the goal of outputting to a photo inkjet printer. If this sounds like you, then the time has come for you to consider the switch to digital, because affordable digital cameras can finally yield the type of quality that you're used to.
Megapixel Mythology
For years now, computer vendors have been waging a "megahertz war" -- comparing computer performance by using processor clock speed as their only metric of quality. Processor clock speed is a huge factor in a computer's performance, of course, but so are bus speed, cache configuration, video card performance, as well as many other factors.
Similarly, digital camera vendors are mired in a megapixel war that will probably never end. By focusing on the pixel dimensions of their image sensors, camera makers can wage a very simple PR battle that pits one simple number against another.
The number of pixels that your camera captures is incredibly important to overall image quality. More pixels mean potentially better detail, better sharpness, and the ability to enlarge and crop a small part of the image. But you only have to look at the latest generation of cameras to see that quality of pixels is as important than quantity.
Consider the Sony F828, one of four 8-megapixel cameras currently available. Though it has almost two million more pixels than the Canon EOS Digital Rebel (which has a 6.3 megapixel sensor) the Rebel takes much better pictures.
The Sony DCS-F828 Cyber-shot has an image sensor that measures 8.8 x 6.6 mm. This is a size that's fairly typical for consumer digital cameras. The Canon EOS Digital Rebel, by comparison, has a much larger sensor -- 22.7 x 15.1 mm, just a tad smaller than a piece of APS film -- and yet the Sony packs more pixels. Obviously, Sony is cramming in those extra two million pixels by using pixels that are smaller than the pixels that Canon is using. Unfortunately, a smaller pixel cannot gather light as effectively as a larger pixel. As such, the Sony camera has a worse signal-to-noise ratio, which results in inferior image quality.
Obviously, it is possible to build an 8-megapixel camera that is better than a 6-megapixel camera. What's important to realize is that the mere presence of extra pixels doesn't guarantee extra quality.
Through a Lens, Sharply
Many people assume that film is inherently better than digital because it must have substantially more resolution than the typical digital camera. Film does, in fact, have a lot more resolving power than a 3- or 4-megapixel camera, but resolution is not the whole story when it comes to image quality.
The best illustration of this is at the low end of the camera spectrum. I hear a lot of people say that, although they considered getting an inexpensive 3-megapixel point-and-shoot digital camera, they finally decided to go with an inexpensive point-and-shoot 35mm camera because, even though it's a cheap camera, it's film so it must have much better resolution.
What these people are ignoring is the fact that if you don't have a lens that's good enough to exploit the resolution at your disposal, then it doesn't matter how much resolution you have.
If you ever roasted ants with a magnifying glass when you were a kid (and I want it on record that I never did, though I did routinely scar and weld plastic model airplanes with a magnifying glass to make them look cooler) then you know that positioning the glass nearer or farther focused a spot of a different size. To focus light onto a piece of 35mm film, you need a pretty large spot and that means a fairly large lens. Unfortunately, the longer and wider a lens gets, the harder it is to engineer. Lens engineering becomes much more complex as a lens gets longer and wider because as you add more glass, it becomes harder to build a lens with good sharpness and few aberrations.
The image sensor in a typical point-and-shoot digital camera is substantially smaller than a piece of 35mm film. As such, digital camera lenses can be very short and narrow because they don't have to focus light onto such a large area. Consequently, it's much easier to engineer a very high-quality lens for a digital camera. In fact, even a cheap digital camera can have a very good lens -- better than what you'd find on a cheap point-and-shoot 35mm camera, and possibly better than what you're used to using on a 35mm SLR, if you've been shooting with a cheap 35mm lens.
Lens quality is so important that many people believe that there's no reason to increase resolution beyond 14 megapixels (when using a sensor that's the same size as a piece of 35mm film) because, at that resolution, we're at the limit of current lens technology. In other words, we don't currently have a lens that could resolve more detail than that, even if we had the pixels available.
Better, Smarter, Faster
This is not to say that digital cameras are perfect, or that you can stick a great lens in front of any old sensor and get a great image. A camera has to perform a lot of gnarly computation and processing to yield a good image, but this is another area that has seen a tremendous level of improvement in recent years.
With each generation, camera manufacturers improve the algorithms that calculate and tweak color, sharpening, and compression. Many vendors are now integrating these functions onto a single chip -- such as Canon's DIGIC image processing chip -- which can be migrated into an entire range of cameras, bringing high-end processing into low-end cameras.
With current technology, you can get the sharpness, detail, and color that you would expect to get from a good 35mm camera. While it's true that digital cameras are susceptible to various kinds of artifacts that film cameras are not -- JPEG compression artifacts, oversharpening artifacts, certain types of color aberrations -- these troubles are easily dealt with and don't necessarily show up in print. Balancing out these issues is the fact that good digital cameras yield much lower noise at higher ISOs than do film cameras. (Just as film can be more light sensitive, you can crank up the sensitivity of a digital camera's image sensor to make it perform better in low light. This sensitivity is measured using the same ISO system as film speed.)
Camera performance is also a critical area that has finally reached film camera standards. A few years ago, many cameras were plagued with unacceptable "shutter lag." After pressing the button, the camera would pause just long enough that it was possible to miss the moment you were trying to capture. Meanwhile, on the high end, cameras could not achieve the fast frame rates that one expects from a film camera, making them unusable for sports or nature photography.
Though some cameras still suffer from shutter lag, in general you don't have to look too hard to find a camera with speedy response. At the high end, digital SLRs can now achieve frame rate and burst sizes (the number of pictures that can be shot in one burst) that exceed what you can expect from a 35mm SLR, meaning you no longer have to sacrifice performance to achieve a digital workflow.
As resolution goes up, so does file size, and that means that film-quality digital cameras can quickly burn through storage. Fortunately, with the proliferation of digital cameras, the flash memory market has reached a critical mass that has resulted in a tremendous reduction in memory card prices.
Similarly, the camera market itself has gone through some tremendous price re-structuring. With the release of the Canon EOS Digital Rebel last year, the entry price for a high-quality digital SLR finally fell below $1,000. Nikon and other manufacturers have followed suit with their own inexpensive digital SLRs, and the rest of the market has shifted its prices so that you can now get an 8-megapixel-prosumer camera for $800.
What Comes Next
There is still plenty of room for improvement with digital cameras. Larger image sensors allow larger pixels, which yield a better signal-to-noise ratio, which results in images with better color and less noise. Hopefully, vendors will one day step out of the resolution race, and begin to engineer less expensive but larger sensors.
Image processing, light meters, autofocus mechanisms, storage media, and battery technology -- these are all subsystems that can always benefit from improvement. But when it comes to the core areas of image quality, performance, and price, there is simply no reason to wait any longer to make the switch to digital.
Over the next few installments of this column, you're going to learn the questions and issues that you need to address when choosing a camera. Along the way, you're going to learn a little more about how the guts of a digital camera work.
At that point, if you're still not convinced, then you can shut off your computer, pop your favorite 8-track into your player, sit back in your beanbag chair, and enjoy your life in the 20th century.
