With the Sony α7 series Sony began to focus its Sony α system away from cameras with Minolta AF mount to mirrorless CSC cameras with Sony E-mount. The α7 series got the FE-mount variant which supports the new full-frame E-mount lenses. Thus the α7 where Sony's first CSCs with 35mm full-frame image sensor. With the Sony α7 II the move of the system's focus was finished by adding a 5-axis sensor shift, making it the first E-mount camera with anti-shake mechanism, a superior one compared to the "super steady shot" of the A-mount DSLRs and SLTs.
|Sony α7 CSC with Sony FE 3.5-5.6/28-70mm kit lens|
images by Hiroshi Uzu (Image rights)
The Sony α7 was the quantum leap in digital photography, by having made a compact mirrorless digital system camera (CSC) capable to shoot "full format" what means a digital frame format equal to the quite ideal former miniature format, better known as 35mm film 24×36mm frame format. Before the α7's launch in 2013 this format was only available in bulky DSLRs, in professional camcorders and in the expensive Leica M9. The CSC has a full format Sony CMOS 24 megapixel image sensor, and a built-in electronic viewfinder. Its retro style housing resembles a Minolta XE. Thus Sony finally embraced the Minolta legacy that it represents since it took over all system camera production assets of Konica Minolta in 2006.
|The Sony α7's Sony E-mount = "All you can adapt ..." ;-))|
image by Nik Chatou (Image rights)
The more expensive variant Sony α7R has a 36 megapixel full format sensor instead, thus being the first non-DSLR system camera offering this high image resolution. Drawbacks compared to A7 include lack of PDAF and EFCS.
|α7R, alike the Sony NEX again a dream for lens adaptions|
image by Nathan Wright (Image rights)
|Sony α7S with fast lens - almost a night-vision device|
image by Ronan Collett (Image rights)
The variant Sony α7S has a 12 megapixel full format sensor and 4K-video-format support. With less but larger pixels it is the low-light queen of Sony's cameras, allowing to shoot autofocus exposures and videos in almost dark places. The low-light advantage for stills is not as much as for video. Camera requires external HDMI recorder for 4k videos, it cannot write 4k on SD card.
|Sony α7 II with Nokton "classic" lens|
image by Marcel Mendoza (Image rights)
Sony α7 II
The Sony α7, but mightily reworked, for example with tiltable monitor instead of a fixed one. Thus it's not as light and slim as the 1st version. Long expected and finally delivered was the anti-shake mechanism, a 5-axis sensor-shift system.
Sony α7R II
The most expensive variant Sony α7R II of mid-2015 has a 42 megapixel full format sensor instead, again the first non-DSLR system camera with such an image resolution. Like the αA7 II it also got the sensor-position-stabilizing anti shake mechanism, a feature that all Sony DSLRs and SLTs had inherited from Konica Minolta'a DSLR, but Sony omitted the feature in the the whole Sony NEX camera series and in the succeeding Sony α cameras for E-mount. The α7R II got a state-of-art 5-axis anti shake, a technology similar to such of Olympus, but different in implementation. It also supports using PDAF with adapted lenses, so it can focus efficiently with A-mount lenses via LA-EA3 adapter and Canon lenses with third party adaptors (most of third party adapters emulate LA-EA3 instead of native lenses) and some others. A7R II is the first E-mount camera which can not only charge via USB, but operate from it.
Sony α7S II
The α7S II gets most of same improvements seen in R II, but it has same sensor as A7S, 12 MP non-BSI sensor without PDAF.