I finally got to get my hands on with the Sony Alpha 7s. My only concern was how it would fare versus my Alpha 99; how much better would it be at high ISO?
For the A99 I usually comfortably shoot up to ISO6400. I wanted to see what that would be for the A7s.
The A99 had the Sony Carl Zeiss Distagon T* 24mm F2.0 ZA SSM, while the A7s had the Sony Carl Zeiss Vario-Tessar T* FE 24-70mm F4.0 ZA OSS in E-mount. Both cameras were placed on approximately the same location on a raised wall with approximately the same framing, manual focus, F11 and exposure compensated with increasing ISO, by selecting a faster shutter speed. Unfortunately, I did not bring a flash, so I’d be subject to the flickering of the flourescent lighting, hence the inconsistent exposure and white balance (the brown tint being the ambient light while the green tint being flourescent.)
All pictures were processed in Adobe Camera Raw 8.5 with the “Previous Conversion” option selected. Everything was flat at 0. The A99 picture was downsampled using Bicubic Automatic to match the output resolution of the A7s. After flattening, the collage below was sharpened with 33% 22 pixel 4 threshold if I remember, and then 200% 0.3 pixel 1 threshold. These are all 100% crops (except the A99 crop – that would be a 70.66% crop.)
Because of the variance in flourescent lighting, it’s hard to truly say, but I’d say what was ISO6400 on the A99 looks like somewhere between ISO25600 and ISO51200 on the A7s. Still, much better than I expected, seeing that DxO seemed to think it was only 1 stop in ISO difference. I thought the A7s would only be worth it, if it could pull 2-3 stops above the A99, if I was to get the LA-EA4 adapter, that would take away under a stop of light. As for why I’d want to put A-mount lenses – there is no equivalent to the Sony Carl Zeiss Sonnar T* 135mm F1.8 ZA or Sony Carl Zeiss Planar T* 85mm F1.4 ZA on E-mount, unfortunately, and I would not be able to crop as much from say the Sony Carl Zeiss Sonnar T* FE 55mm F1.8 ZA on a mere 12-megapixel A7s.
I was also largely uninterested in the A7 because it was merely 24 megapixels, and I had 24 megapixels since the A900 so this brought nothing new; the A7r meanwhile had 36 megapixels, quite exciting, but it lacked the Electronic First Curtain shutter that the A7 and A99 had, so it had a shutter lag that would not work for action and flash photography. The A7s is better, by having Electronic First Curtain and Electronic Second Curtain so it’s completely silent. In the menu however it’s called Silent Shooting.