Monday, January 7, 2008
D-SLR Wars: Episode III
Resolution always will be a buzzword for digital cameras, but the current crop of professional-quality D-SLRs is about much more than advances in megapixel counts
The war of technology is raging with renewed vigor as the next installment of weapons has come to the battlefield. Product development, with its furious and relentless pace, has taken us one step further into the golden age of digital photography. But that step is now at least as much about features and new onboard technologies as it is about gains in resolution. While we expect manufacturers to continue to develop higher-resolution sensors—as shown by the latest gains across the industry—we're seeing a fundamental shift away from resolution as the big story.
Larger LCDs and full live-view shooting with the LCD, 14-bit RAW capture, better noise reduction for shooting at higher ISOs, live histogram displays, automatic sensor cleaning, bigger and brighter viewfinders, and faster and more powerful processing engines—these are the features driving innovation right now. Part of the deemphasis on resolution comes from the simple fact that packing more and more photosites on a sensor ultimately leads to diminishing returns. At a point, the individual photosites would get so small it actually would degrade image quality. The smaller the photosite, the fewer photons it can collect for a given exposure—noise increases and dynamic range, detail and color saturation all drop. How much they drop depends on how small the photosites get.
That's certainly one of the reasons why we're seeing most of the available D-SLRs coming in at 10- to 12-megapixels this year. Other issues are cost, of course, and performance of both the camera and the computers on the back end of the processing workflow. Who wants to shoot images that require a Defense Department supercomputer to open?
Manufacturers are constantly working to find the right balance between sensor size, the number of pixels, the size of those pixels and the cost of production—while focusing on other ways to improve image quality like bit depth. Having the option of 14-bit RAW capture is one of the latest trends taking hold. It's in all the new Canons and Nikons. Compared to 12-bit, there's a noticeable difference in color and tonal rendition, plus there's just so much more image information to work with for Curves and Levels adjustments in Photoshop. A 12-bit file has 4,096 discrete levels of color and tonal information per channel (RGB); a 14-bit file has 16,384 levels per channel.
Faster processing engines and buffers are bumping sequential, high-resolution capture rates to an average of 5 fps. Metering and autofocus systems are getting faster and more accurate. The Nikon D3 and D300 have a new 51-point AF system. Both Canon Mark IIIs have a new 45-point AF system. Throw in some improved noise reduction, working in tandem with increased ISO sensitivity, and you get low-light shooting capabilities you'd never have thought possible. At the high end, ISOs of either 1600 or 3200 are now commonplace and some go much higher. The new Nikon D3, for example, can be set at a maximum ISO of 25600 (in Hi-2 mode)!
Olympus, Pentax, Samsung and Sony have developed built-in sensor-shift technology to deal with camera shake, while Canon, Nikon and Sigma have opted to build stabilization technology into their lenses. Panasonic has stabilization in both the body and lens.
Whether sensor-shift or optical stabilization is better certainly is debatable. For instance, in-lens antishake allows you to see the effect as you shoot; on the other hand, in-camera stabilization allows you to use almost any lens. Although the technologies are very different, they both minimize or eliminate shake in nearly any situation, on or off the tripod. In low-light conditions, you can shoot, on average, four shutter speeds slower than your normal handheld limit. It's a beautiful thing.
Page 1 of 7