Sony A7s II vs A7r II (APSC) vs A7r II (full-frame): 4k UHD / 25P / 100 Mbit from Gordon Laing on Vimeo.
CameraLabs posted the full Sony A7sII review and writes:
If you do film under the conditions where the A7s II takes the lead, then go for it in the knowledge you have the best tool for movie-making at this price point. And even under conditions where the A7r II would match it, the A7s II remains a superb choice. But there’s no denying the A7r II has proven one camera can almost do it all and erodes much of the desire or necessity for a more specialist product. It will be interesting to see where Sony takes the A7 series in a third generation – I feel the S version needs more to differentiate it, such as 10-bit internal recording, but Sony has to be careful not to step on the toes of its professional FS models. Meanwhile the R team could progress to a point which renders an A7s Mark III unnecessary. But that’s just speculation. Today the A7s Mark II is the best camera at its price for filming 4k video in low light and comes recommended, but do compare it very closely with the A7r Mark II as you could find it already does everything you need while offering more besides.
Also ePhotozine tested the A7sII:
The are a number of improvements over the previous model, including improved handling and controls, additional focus points, as well as the excellent 5-axis image stabilisation system, and internal 4K video recording. However, as competitors (and Sony) have increased megapixels and began offering 4K video, the case for the A7S has become slightly less clear. For those that own the original A7S, the A7S Mark II is going to make an excellent upgrade. The range of FE lenses available has also increased, and if you can look past the 12 megapixel resolution, then the A7S Mark II is capable of producing excellent images.
Sony A7sII store links: Amazon, B&H, Adorama, eBay