The mirror design directs incoming light to the CMOS image sensor and the AF sensor at the same time, allowing full-time continuous AF during both still and video shooting.
You can also frame, focus and preview shots in real-time on the electronic viewfinder, which offers a wide viewing angle and 100% field of view.
The a57 is the successor to the a55.
It can shoot still images at up to 12 frames per second, capture full HD video at 60p, 60i or 24p frame rates and has a variety of creative modes including Auto Portrait Framing
With the a57, shooting speeds of up to 12 frames per second are achieved in new Tele-zoom Continuous Advance Priority AE mode, maintaining continuous autofocus and auto exposure with fixed aperture. Magnifying the central portion of the sensor’s image by 1.4x, Sony says it’s perfect for capturing split-second action close-ups with a burst of sharply focused images, even when the subject is moving.
In this shooting mode, aperture is fixed at either f/3.5 or the maximum aperture of the lens in use (whichever is smaller) and image size of photos is about 8.4 megapixels.
With Full HD movies, full-time continuous phase detection AF ensures that moving subjects stay sharply focused.
Support for the AVCHD Ver. 2.0 (Progressive) format means that Full HD resolution movies can be captured with 60p frame rate. Shooting in 24p is also available to give footage a rich, cinematic look.
Movie-making options are enhanced further with full control over P/A/S/M shooting modes.
The a57 shares the a65’s 15-point AF system with three cross sensors delivering fast, accurate TTL phase detection autofocus. Newly enhanced Object Tracking AF keeps faces or other selected objects in sharp focus – even if a target is obscured momentarily by another passing object.
With Auto Portrait Framing, using face detection and the compositional ‘rule of thirds,’ the camera identifies a subject’s position, trimming the scene to create tightly framed, professional-looking pictures in portrait or landscape orientation while maintaining a copy of the original image. Saving both the original photo plus the adjusted version allows for easy comparison between the two images.
To get closer to the subject, 2x Clear Image Zoom digital zoom technology doubles the effective magnification of the lens. Sony suggests this is “a highly practical alternative to travelling with a bigger, bulkier telephoto lens.” The camera uses Sony’s “By Pixel Super Resolution Technology” to ensure cropped and zoomed images retain full pixel resolution.
The new model’s range of in-camera Picture Effect modes includes 11 different effects and 15 total variations – including Pop Colour, HDR Painting, and Miniature Mode. Results can be previewed directly in live view mode on the LCD screen or in the electronic viewfinder while shooting either Full HD video or stills.
The new Tru-Finder electronic viewfinder, with 1.44 megapixel resolution and a 100 percent field of view, rivals quality optical viewfinders, says Sony. There’s a choice of selectable high-resolution information displays with a wide viewing-angle, including a digital level gauge and framing grid. Information can be displayed either directly in the viewfinder or on the angle-adjustable 7.5 cm (3.0-inch) LCD display.
The effective 16.1-megapixel Exmor APS HD CMOS sensor is teamed with a latest-generation BIONZ engine, the latter refined by Sony during the development of its flagship a77 and high-end a65 cameras. The company says the processor effortlessly handles large amounts of image data for flawless, low-noise images and Full HD video.
The sensitivity range is ISO 100-16,000.
Update: Sony Canada says the a57 will be available in April with an 18-55 mm kit zoom lens for $799.99; body-only for $699.99.