Mirrorless interchangeable lens cameras offer consumers DSLR-like performance in a much less bulky package, but prothusiasts looking for something bigger than an APS-C sensor may still have to lug around a larger and heavier camera. The playing field is changing though. Panasonic has managed to squeeze a Micro Four Thirds sensor into a body that's smaller than many compact cameras for its new GM1, and now Sony's upped the ante even further. The Alpha 7 and 7R are claimed to be the world's first 35 mm full-frame mirrorless cameras.

Sony α7R

The 36.4 megapixel α7R is claimed as the world's smallest and lightest full-frame interchangeable lens camera, with body-only dimensions of 126.9 x 94.4 x 48.2 mm (5 x 3.7 x 1.9 in), and weight of 407 g (14.4 oz). Within its water- and dust-resistant magnesium alloy body is a 35 mm full frame (35.9 x 24 mm) Exmor CMOS sensor with light concentration, photo diode technologies and a new gapless design that gets rid of gaps between adjacent pixels for more efficient light collection and improved image resolution. Image sharpness is also helped by the lack of an optical anti-aliasing filter.

The camera features a new BIONZ X image processor that's reported to be about three times faster than previous versions, and offers area-specific noise reduction and "faithful" color reproduction. The α7R has ISO100 to 25600 sensitivity for stills or movies (though this can be expanded to 50 - 51200), a top continuous shooting speed of 4 fps, and is said to get about 340 stills from its 1080 mAh InfoLithium battery between charges.

The camera has a customizable 25-point contrast autofocus system that Sony says is 35 percent quicker than other contrast-detection systems, and continuous AF tracking. It's compatible with Sony E-mount lenses, including six new full-frame Zeiss lenses launched simultaneously with the new Alpha camera, but full-frame A-mount adapters are available. Ultrasonic vibration and an antistatic coating help keep dust and other small particles from finding a foothold on the sensor when changing lenses.

The α7R has built-in Wi-Fi for remote viewing, exposure control or shutter release on a smartphone, and NFC technology for one touch sharing with an Xperia or compatible Android smartphone/tablet. It supports stills in JPEG and 14-bit RAW image formats, and is capable of 1920 x 1080/60p video recording (which can be stepped down to a cinematic 24p). Though the camera has its own stereo microphone, there's also a 3.5 mm mic input jack to connect an external microphone.

The display of high res stills on a 4K TV, such as the company's Bravia models with a Triluminous display, via built-in HDMI or over W-Fi is also possible.

The 2,359K dot OLED electronic viewfinder (which can also be found on the company's α99 camera) offers 100 percent field of view and 0.71x magnification. The camera also has a 3-inch, 1,229K dot tilting Xtra Fine LCD panel, with five step brightness control.

The camera has manual exposure control, a rear control wheel and nine user-customizable buttons. Face detection can track up to eight faces, there's a feature called Eye AF where users can prioritize which eye the autofocus concentrates on when capturing an angled close-up, and creativity options like auto HDR and sweep panorama are also available.

Sony α7

Sony's other new addition has similar specs to its Alpha cousin, but there are a few key differences. For starters, the 35 mm full frame Exmor CMOS sensor in this model has slightly different dimensions (35.8 x 23.9 mm), and a reduced pixel count of 24.3 megapixels.

The camera has been treated to the same same BIONZ X processing engine, with similarly impressive low light prowess, but its continuous shooting capability has been increased slightly to 5 fps.

This model has a low-pass filter, and uses a hybrid autofocus system (helped along by a new Spatial Object Detection algorithm for an extra performance boost). The 117 phase detection AF points bring the subject quickly into focus, and precision fine-tuning is undertaken by 25 point contrast AF.

It packs the same Tru-Finder EVF and tilting LCD display as the α7R, and also benefits from integrated Wi-Fi and NFC technologies. Full HD video recording with stereo audio is included, and there's a HDMI out port for display of content directly on a big screen TV.

Both Alpha cameras are due for release in December. The α7R has a body-only price of US$2,300, and the α7 will be $1,700.

The video below shows the SGNL by Sony team introducing the new cameras, and revealing that new Sony E-mount cameras will now all be branded Alpha, so there'll be no more NEX models.

Product page: Sony α7R, Sony α7

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