Which is the right camera for you? Obviously, that depends on what you’re shooting. If you do action, you need a camera that shoots rapidly and has quick AF, for example. But don’t fall into the "best" trap: Some feel they’re not really "pro" if they don’t have the top-of-the-line model, or worry that a client will see them with a mid-level DSLR and say, "Hey, my kid has that same camera." Some need the gravitas that’s implied by a big, top-of-the-line DSLR, which, as strange as it sounds, is legitimate. You don’t want to lose work simply because a client decided that only an amateur would use a certain model of camera. But if you’re not in that situation, here are some considerations to help you make sure you get the camera you need, not one that overperforms where you don’t need it and underperforms where you do.
While you still can’t beat a high-end medium-format DSLR for resolution and image quality at low ISO, full-frame DSLRs offer near-medium-format quality at a fraction of the price and in a more mobile package. Nikon’s D800 and D800E, with their 36.3-megapixel, full-frame sensors, currently top DxOMark.com’s sensor ratings with scores of 95 and 94, respectively. This tops even the best medium-format sensor—a $40,000, 80-megapixel unit—in overall performance, taking into consideration color bit-depth, dynamic range and high-ISO performance.
Leaps In Technology That Translate To Superior Image Quality
In the last few years, we’ve seen a couple of interesting DSLR image-quality advancements. Nikon’s D800E and Pentax’s K-5 IIs do away with the anti-aliasing low-pass filter common to other DSLRs (medium-format cameras don’t have these filters). The photodiodes (pixels) on an image sensor can’t detect color; they just know how much light is striking them. To get color information, conventional image sensors have a grid of red, green and blue filters (called a Bayer array) over the pixels, so that each pixel receives only red, green or blue light. The missing colors for each photosite are calculated using data from neighboring pixels in a process known as demosaicing. This process produces some undesired artifacts (moiré), and these are dealt with by placing the anti-aliasing filter over the pixel array to slightly blur the image.
When pixels get down to a certain size (apparently around 4.8 to 4.9 microns, as these are the pixel sizes for the K-5 IIs and D800E, respectively), the artifacts aren’t so bad, and can be handled in postprocessing. So the D800 and K-5II are offered in two versions—one with a conventional anti-aliasing filter and one without—so the "without" version doesn’t suffer the loss of sharpness caused by the filter, providing even sharper images.
The other image-quality development was the introduction of a higher-resolution Foveon X3 sensor in Sigma’s SD1 DSLR (and, later, in the DP1, DP2 and DP3 Merrill fixed-lens compact cameras). Introduced about 10 years ago, the Foveon X3 sensor doesn’t use a Bayer array to get color data. Rather, it stacks three pixel layers and takes advantage of the fact that light wavelengths penetrate silicon to different levels: blue only so far, green farther and red the deepest. Thus, every pixel site receives light of all three colors, more of the total light striking the sensor is collected, and there’s no need for the blurring low-pass filter. While it’s a bit more complicated than that, the result is that the Foveon sensor delivers resolution well beyond that of a conventional Bayer array of equivalent horizontal-by-vertical pixel count. The new Foveon X3 sensor introduced in the SD1 has three times the pixel count of the previous one.