Originally posted by joergens.mi But he is talking about a little bit more sensitive to dark current. I think you put to much emphasis on the factor of 4, which is one the factors relevant for the quality of pictures.
The numbers he gives is factor 4.
Originally posted by joergens.mi He also says, that there isn't any problem below 40°C on the sensor, and tells us that an active cooling will improve the results for dark scenes and times above 1/10s.
Sure. The question is, what is "problematic" given the detail loving discussion we have on forums?
If it is worth mentioning that cooling will improve results from 1/10 s on then obviously there is impact enough.
There is a good reason for LENR / darkframe subtraction even in normal environments for long exposures, because even then you get visibly more noise in the images with non-BSI sensors. And all this is being caused by the sensor heating up a few degrees.
It is not dramatic, but it is there.