Last week I did some nighttime photography in B mode, with exposures between 1 minute and 15 minutes. As exposure times grew longer, the number of hot/warm and dead/cold pixels increased.
Does anyone know if it is supposed to happen this way, that the camera dark-frame noise-reduction becomes less effective at long exposures? If so, I wonder how many bad pixels can be considered acceptable. Cloning them out manually is a recipe for madness...
Also, I noticed that after going through a pixel mapping, the camera did not return to normal operation. The LCD panel displayed "0s nr", in the same way as it displays remaining time for dark-frame subtraction after a B exposure. It remained this way until turned off and on again, or until meter operation timed out and reactivated by half-pressing the shutter.
The pixel mapping had no effect whatsoever on the occurrence of bad pixels in B mode. Same pixels, same hotness/coldness.
Anyone having similar experiences?
Thanks,
Jostein
PS firmware version: 1.11.