Sony SLT-A77

After a four-year wait, Sony has returned to the enthusiast/semi-pro end of the DSLR market. Having made little impact in that market with the A700 that very closely resembled the conventional DSLRs made by Canon and Nikon, Sony has spent the intervening time developing something a bit different. The A77 builds on the company's 'translucent mirror' technology, and uses an electronic rather than optical viewfinder. The final result is a product that may look traditional, but is able to promise the unconventional.

Spec-wise the A77 is impressive: it features a new 24MP APS-C CMOS sensor, 12fps full-resolution shooting and the highest resolution EVF we've ever encountered (a 2.4M dot OLED finder). It also uses a new 19-point AF sensor, 11 points of which are cross-type (sensitive to detail in both the vertical and horizontal axis). Clever use of the main sensor's live view allows the A77 to track objects as they move across the frame, enabling the camera to have a better understanding of which AF point it should be using at any given time.

Last year's SLT-A55 gave some clues about how Sony hoped to bring its electronics know-how to bear in a high-end camera. Its fixed, semi-transparent mirror design meant Sony could do away with a conventional optical viewfinder and use an electronic display. It also meant that the phase-detection autofocus that gives DSLRs much of their immediacy could be used all the time. The result was a camera that could shoot at an impressive 10fps, could focus quickly in video mode and offered full-time live view with consistent DSLR-like behaviour in a way that no camera had really managed before.

Unsurprisingly the A77 takes all these capabilities a lot further than the consumer-level A55 - it combines the latest processor with an electronic first curtain shutter to offer the level of responsiveness the more demanding enthusiast/semi-pro users will expect. The A77's massively improved viewfinder is also key to ensuring the A77 can hold its own against the very stiff competition it faces from the likes of Canon's 7D. (You don't have to read particularly far between the lines to conclude it was this feature Sony wanted to perfect before launching an SLT into this market.)

And, as with the A55 and a handful of other recent Sony cameras, the A77 offers in-camera GPS. It can be a really useful feature for organising and retreiving images, as allowing tagged images to be geo-located on sites such as Flickr. As with all GPS settings, it can take a while to locate enough satellites, or struggle to find them at all in built-up areas. Then, of course, there's a battery penalty to be paid.

In addition to the technological advances, Sony has clearly been listening to its audience when developing the camera's firmware - the A77 is not just the most customizable Sony we've ever encountered, but that customization includes a number of long asked-for features. In addition to the ability to fine-adjust the AF tuning, Sony has added the ability to define the upper and lower extremes that the Auto ISO system will use - a step we suspect many users will welcome.

But despite all this technological wizardry, the A77 is actually a remarkably conventional-feeling camera. It may have a plastic top-plate, rather than the A700's tank-like magnesium-alloy construction, and use SD rather than CF cards, but in pretty much every other respect it looks and behaves like a logical progression of the series. Overall, despite the fact that it embraces a rather different set of technologies, it feels and behaves much like a conventional semi-pro DSLR.