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Much as the Sony Alpha 100 was last year's breakthrough camera, the new Sony Alpha 700 ($1,400 street, body only; $1,900 with 16-105mm f/3.5-5.6 Sony DT lens) charges in as the very first 12MP-class consumer DSLR. As we've noted in our field test, the A700 uses a 12.2MP CMOS imager in a rugged, weathersealed metal body. Viewing, autofocus, exposure, and image-processing systems are seriously upgraded from the Alpha 100.
In the Pop Photo Lab, the camera lived up to its advance billing in image quality, with Excellent resolution results throughout its ISO range. Performance was particularly strong at higher ISOs -- 1600 through 6400 -- where noise suppression causes many DSLRs to take a heavy hit in sharpness. At ISO 1600, resolution was 2160 lines average; at 6400, 2050 lines average. That equals or beats the Nikon D200 at ISO 100.
The A700 kept noise to Low or better through ISO 800, and Moderate through ISO 3200. Noise just barely slipped into the Unacceptable level at ISO 6400 with a score of 3.1. Though good, this isn't up to scores from the Nikon D80 or Canon EOS 40D.
Still, given these numbers, and a color accuracy score of 8.9 (with 8.0 being the cutoff for Excellent), we judge the overall image quality Excellent up to ISO 800, and Extremely High through ISO 3200.
The A700's JPEG processing is clearly designed to emphasize image sharpness, especially at higher ISOs. Minimally adjusted RAW test images showed about 10 percent lower resolution than JPEGs -- the reverse of what we usually see.
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Sony claims greater speed and sensitivity with the new camera, though it uses a diamond-grid autofocusing array similar to the A100's. Our tests confirmed this -- for the most part. It autofocuses faster than the A100 at EV 12 through EV 4 (bright to moderately low light), and works down to an inky EV -2, where the A100 fails to autofocus. But in very dim light (EV 2 through EV -1), the A700 is slower than its stablemate by a fraction of a second.
It also focuses faster than the Canon EOS 40D, Nikon D80, and Nikon D200 down to EV 4, then gives up a fraction of a second at EV 2 through -1. It's slower than the Canon at EV -2, but faster than the Nikons. And it focuses faster at all light levels than either the Pentax K10D or the Olympus Evolt E-510.
In daylight, with all 11 sensors and continuous AF activated, the A700 works very well for tracking a subject moving across the frame and for panning an irregularly moving subject.
We also tested Sony's claimed burst rate of 5 frames per second, limited only by the capacity of the card. With a 2GB Kingston Ultimate 266X CF card in the camera, we set it to 12MP fine-quality JPEGs, and held down the shutter button. Exactly 1 minute later, it had devoured 300 shots (5 fps) and kept firing.
While the Canon 40D and Nikon D300 have nominally faster burst rates (6.5 fps and 6 fps, respectively) they're limited by their buffer size to 75-160 shots.
The A700 can take up to 20 RAW or 12 RAW + JPEG shots at 5 fps. And it continued chugging away at a slower framing rate -- more than 2 fps with RAW files, slightly less than 1 fps for RAW + JPEG.
The burst rate can slow down or stall with a slower memory card, as it did when we tested it with a 2GB Kingston Ultimate 100X CF. And if you want fast framing, don't use the Extrafine setting, a minimally compressed JPEG; the camera will start choking after 8 or 9 full-res frames. But otherwise, it's tough to miss a shot because the camera is too busy talking to the card.
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