>>4189657E mount is able to support lenses as fast as f0.63.
The "baby mount" bullshit only affects 3 things. The first is incidence angle, which slightly affects vignetting, which the camera automatically corrects for. If you have very good eyes, you may notice an extra stop of noise in the far corners, which due to the performance of modern sensors, would not be humanly noticeable until ISO 1600 or 3200, which is not a quality-critical sensitivity level anyways. Nobody has noticed this so far because nobody looks critically at image corners except 1: non-photographer gearfags who buy cameras just to leave them pointed at a chart 2: a soulless computerized automaton that measures the minutiae of camera performance paying no mind to real world experience (yes, i am talking about two different things!).
The second thing is it affects lens design. It is not possible to make a telecentric lens if the mount is too small, which prevents sony from making a true pancake lens and means the lenses will normally get larger as the parameters get more extreme. But canikon's lenses, despite their larger mount, are comically large, so maybe it doesn't matter that much.
The other thing it affects is your ability to measure cocks and feel better about only having a canon 6d you found at a yard sale, and to add insult to injury, never even using it!
>>4189616The sony A7RIII is basically the size of the A7C but with a bigger viewfinder and the proper ergonomics. However, sony did not improve their weather sealing until the later models (s3, a7c, etc). The A7IV/A7RIV is as close as it gets to what you want+won't throw up "lens error" constantly if it gets wet, but is slightly thicker.
The nikon Z bodies "good" line starts with the Z6II and they have an actual pancake lens (26mm), but the bodies are a touch larger than sony. You might like that, you might not.
With either brand you can adapt a lot of nikon lenses, but you can't adapt any with screw driven AF to nikon Z mount.
