With this morning’s announcement of the Alpha a57, Sony’s line of translucent mirror cameras continues to impress. Like its innovative predecessor, the a55, the a57 makes use of a translucent fixed-pellicle mirror rather than a standard SLR mirror that must swing out of the way to allow light to reach the film or sensor. Because the shutter doesn’t have to wait for any other moving parts, these cameras are remarkably responsive and fast. Setting a new record for the sub-$1000 camera range, the a57 is capable of shooting action at 12 frames per second! Only the new Canon EOS 1D X is faster (at nearly 10 times the price), though the a57 can only achieve top shooting speed while shooting smaller, 8.4 megapixel images at a maximum aperture of f/3.5. At full resolution, it still shoots an impressive 10 fps, however.
Shunning the 24.3 megapixel sensor of the a65 and a77 , the Sony a57 uses a tried and true 16.1 megapixel sensor that is well regarded for its low light performance and overall image quality (the Nikon D7000 uses a very “similar” sensor made by Sony). Because the pellicle mirror blocks a percentage of the light that passes through the lens, the a57 will never perform quite as well as a standard SLR in the same situation, but because the camera uses an electronic viewfinder, Sony claims that their mirrors eat only 1/3rd stop of light, which, if true, is practically negligible, given the performance of modern sensors. In fact, the ISO range of the a57 is 100 to 16,000 (an unusual number, slightly less than 1/3rd stop above 12800, perhaps attributable to the mirror’s light loss).
Unlike the Canon 1D X, the Sony’s auto-focus system relies on 15 focusing points (rather than 61), but they are available full time, whether the photographer is tracking, shooting stills, or shooting video. The a57 boasts 60 (progressive) frame per second shooting full HD video. Sony also added some additional bells and whistles: an articulated LCD screen, in-camera HDR, 2x digital zoom, and auto-portrait cropping based on the rule of 3rds (for those who really don’t want to think about the pictures their taking). And, as we expect from Sony cameras, image stabilization is built into the body, so we can shoot (relatively) worry-free with any lens.
The Sony a57 is expected to be on store shelves in April for $699. It is currently available from B&H for pre-order.
