Quote:I am surprised by your comments and have to disagree. With the A7s you mentioned, the ability to focus accurately in low light is unprecedented. AF works down to quite low levels and after that accurate MF is possible in levels where you can barely see with the naked eye. Compared to any DSLR i tried, the accuracy of AF and MF is much better - especially with fast primes in low light. DSLR make too many focus errors with fast lenses in low light. There is an issue with speed which can be slower than DSLRs (particularly in AFC) but the accuracy and light level operating window is much better
The problem is that fine spot AF (which I am using all the time) is lost in very low light. In this case the camera is expanding the AF field to look at the "grand picture".
That is not really surprising - the sensor noise is very high in such a situation and this has impacts. The same is true for DSLRs but the AF photodiodes are MUCH bigger thus not quite as prone to noise.
I haven't used the A7S (II) - it's probably much better than on the A7R II - but I still doubt that it goes down to DSLR levels here based on spot AF. Feel free to correct me though.
As mentioned we would have to define what "low light" means. I am talking about -say- 10 candles in the living room here and focusing on a person with fine spot AF.