With a unique 12-megapixel 35mm sensor, the Sony A7S is able to shoot in very low light with impressive high ISO performance, up to ISO 409600! The sensor is tailor-made for 4K video for excellent detail, plus very wide dynamic range. XAVC S high bitrate format provides higher quality Full HD video, plus expanded pro-level video features such as SLog2 gamma make for a solid hybrid photo/video camera. This sensor was made for very low light surveillance appliances and night video/photography, which makes it an excellent sensor for astrophotography too. This is the reason I bought this specific model, the first of the series A7S. You might be tempted to buy a much more expensive II, III, etc. generation, but their improvements are not about the most important piece for astro, the photosensor, which is pretty much the same also for the bigger sisters.

Sensor Type: CMOS
Sensor Manufacturer: Sony
Effective Megapixels: 12.2
Sensor Format: 35mm
Sensor size: 847.28mm2 (35.60mm x 23.80mm)
Approximate Pixel Pitch: 8.40 microns
Focal Length Multiplier: 1.0x
Aspect Ratio: 3:2
Color Filter Type: RGBG
Anti Aliasing Filter: Fixed
Self-Cleaning: Yes
Sensor shift image stabilization: No
On-Sensor Phase Detect: No
DxO Sensor Score: 87
DxO Color Depth Score (bits): 23.9
DxO Dynamic Range Score (evs): 13.2
DxO Maximum Effective ISO Score (iso): 3,702