Has anyone experimented to find out if the eyepiece cap should be on the DSLR when taking dark frames or, for that matter, light frames?
Its purpose is to keep stray light out of the exposure meter when the camera is not held up to someone's eye.
I strongly suspect no stray light would get on the sensor without it, because the mirror (flipped up) is in the way.
But I'm not sure.
I know that another problem with taking darks in a light environment is that lens caps may not be quite opaque, especially in the deep red and infrared.
For a long time, my practice has been to put the eyepiece cap (as well as lens cap) on when taking darks if I am going to have any lights on, even intermittently. But has anyone experimented?