Sony's current ISO sensitivity champ is the mirrorless A7S, which can be pushed to an outrageous 409,600 ISO. However, that camera has a mere 12-megapixel sensor, making it more suited for 4K video than stills. Sony claims that the A7R II delivers both low-light performance and high-resolution thanks to the 35mm-sized back-side illuminated (BSI) sensor, with an ISO range of 100 to 25,600, expandable to 102,400. The full-frame, E-Mount camera also has a 399-point phase-detection AF that sports a 40 percent faster focus than the A7R, with up to 5fps continuous shooting.

The new model's 5-axis image stabilization is borrowed from the 24.3-megapixel A7-II, but fine-tuned for much higher resolutions. It corrects pitch, shift, yaw and rotational shake, especially useful for telephoto and video shooting. Stabilization works on the 12 native full-frame E-mount lenses, or with A-mount models via an adapter. Sony claims the compensation is equivalent to shooting around 5 shutter-speed steps faster. To read out the 42.4 megapixels quicker, data speeds are also 3.5 times quicker than the original model. Helping photographers deal with the resolution is a new XGA optical viewfinder (2,359,296 dots) that Sony claims has the world's highest magnification (0.78x).

As for video, Sony may have the unicorn of DSLR/mirrorless camera video: 4K video with no pixel binning, which it calls another "world's first." The A7R II reads out the entire 35mm sensor and oversamples it before reducing to 3,840 x 2,160 at 30fps or 1080p at 60fps, resulting in sharper video with fewer artifacts and a shallow depth-of-field. It also uses reasonably high bit-rates: 100Mbps for 4K video, and 50Mbps for 1080p, using Sony's new XAVC recording format. The camera also supports super-35 cropped 4K and clean HDMI output in 4K or HD, but only at 8-bit 4:2:2, unfortunately.

As for the when, where and how much, the A7R II is coming to the US in August for a bank-breaking $3,200. We haven't yet spotted UK pricing and availability, but will let you know when we do.