Sony produces two interchangeable lens lines -- traditional dSLR and so-called single-lens translucent (SLT), which uses a translucent mirror with a digital viewfinder. The A57 falls into the latter camp. It looks and works just like a dSLR but it has a faster burst mode for taking rapid sequences of images.
Specs and handling
Stand it beside a dSLR and you can't tell them apart. There's a top-mounted mode selector with direct access to two automatic modes, sweep panorama, movie and regular semi-manual modes with aperture and shutter priority. There are also program and manual modes if you want to be really hands-on. The handy finger wheel around the front handles adjustments.
Its native resolution is 16.1 megapixels on an APC-C-sized sensor, with sensitivity running from ISO 100 to ISO 16,000. The lens mount accepts all Sony dSLR lenses and A-mount bayonet lenses from Minolta and Konica Minolta. So if you have a library of lenses built up before Sony bought that company's camera business, you can recycle them here.
The longest exposure time is 30 seconds, backed up by a bulb option, which holds open the shutter for as long as you keep the button pressed (you'd be advised to buy a remote if you want to use this mode), while the shortest is 1/4,000.
Sony claims that the Bionz processor can handle large amounts of sensor data for high-speed shooting, and that was certainly the case during my tests. A burst mode fires up to 12 shots per second, making it easy to capture motion as a series of stills.
The animation below shows a 21-frame sample shot at that rate, but looped at 10 frames per second, so that actual captured data ran slightly quicker than seen here. For anyone who needs a camera for performance analysis -- say in sports -- the A57 is certainly up to the job.
This is where a camera lives and dies. I performed my tests shooting raw and JPEG images side by side, but I used the in-camera JPEGs for analysis. The results were sharp and crisp on contrasts and extremely smooth across areas of similar tone. Colours were punchy and luminance was well balanced, adding up to an impressive set of results overall.
I performed my tests using the SAL1855 18-55mm kit lens, so the results below are indicative of that particular unit. If you choose a different lens, your own output will differ. This lens behaves like a 27-82.5mm (3x zoom) unit on the APS-C-sized sensor in the A57. It's not an enormous range, but these measurements are pretty standard for a consumer dSLR's bundled lens.
The lens geometry is spot-on, with no evidence of barrel or pin-cushion distortion (parallel lines bowing out or in, respectively) in my tests.
Macro performance with this lens was very impressive. It was easy to isolate the exact part of the shot I was after, despite the minimum focusing distance topping out at around 21cm in my tests. It was quick to focus, and allowed me to pick out this family of aphids living inside a flower -- along with the stamen at the bottom of the petals. Outside of the sweet spot, it threw the surrounding detail gently out of focus, helping draw the eye to the subject.
It did extremely well in the chromatic aberration test. This reveals how effectively a lens focuses each wavelength of light in the visible spectrum in sync with the rest of the spectrum. Lenses that don't focus each tone perfectly in line with the others will render a pink or turquoise fringe around areas of fine detail against sharp contrasts, which is particularly visible in the corners and edges of the frame.
There's no such problem here. The SAL1855 kit lens focused everything perfectly for a crisp set of results. Detail was consistent right across the frame throughout my tests.