A Sony alpha 7S arrived yesterday for testing. Same origami box as the other alpha 7 cameras. Same lightweight documentation. Two nice differences: the a7S ships with two batteries and a battery charger. I guess they figure videographers will be going through batteries at a good clip.
In one sense, the arrival of the camera is timely; I’ve been doing simulations of large and small pixel cameras, and here is one with a modern large-pixel sensor. In another sense, it’s too soon; I haven’t finished the simulation work, and I’m in the process of recovering from a disk failure on my main computer. Not to mention the holiday weekend coming up. Mindful of the interest in this camera, I’m going to press ahead on all fronts.
I’m curious about several aspects of the a7S:
- What are the characteristics of the sensor with respect to the ISO setting? Other reviewers have indicated that the camera is not “ISO-less”. I’d like to find out for myself. The camera is not (quite) ISO-less. Images here.
- How much aliasing and false color do we get with sharp lenses focused on big pixels? What kind of antialiasing filter does Sony have on this camera? Images here.
- How well does the camera work in fully electronic shutter mode? We know it won’t be able to tolerate a lot, but can it tolerate a little camera or subject motion? Test results here.
- What games has Sony played with the raw files and the analog to digital converter settings? We can expect the Sony raw compression scheme, but is it changed in what people are saying is a camera with a 14+ bit engineering dynamic range? I don’t see how the old 13 bit to 11 bit to 8 bit delta modulation scheme could support that much DR. [Added 7/17: From examining the file sizes, it looks like the A7S uses the same raw compression algorithm as the a7 and a7R.]
- What is the intra-scene DR under various conditions (and various definitions of DR)? Read-noise-limited DR information is here. Read noise vs shutter speed information is here. Photon-noise limited-DR information is here. How about the inter-scene DR, assuming the camera is not ISO-less? It in indeed greater than the intra-scene DR.
- How does the large pixel sensor fare with third party symmetric wide-angle lenses like those made for the Leica M-series cameras? It should be better than the a7R and the a7 with respect to corner smearing and color casts. Zeiss 35mm f/2 Biogon in the Leica M-series mount. Leica 16-18-21mm f/4 Tri-Elmar ASPH. Leica 28mm f/2.8 Elmarit ASPH. Leica 50 mm f/1.4 Summilux ASPH. Leica 24mm f/3.8 Elmar-M ASPH. Leica 18mm f/3.4 Super-Elmar-M ASPH. Summary.
Plenty to work on.