Posted by Graham Relf at 11:51 on 2013 Dec 20
Yes, I do have a flat box (cardboard box lined with white paper, 4 torch bulbs in the corners next to the circular aperture that goes over my telescope). I still do not often use it. I agree that it’s a simple way to fix vignetting but I tend to do that in post-processing (various methods).I would certainly use my flat box if I had any optics between my telescope and the camera body (to magnify the target*) because there is then a risk of out-of-focus dust spots and rings which a flat frame would correct.(* or perhaps a coma corrector but again I have one but don’t use it because I found it introduces other problems such as ghosting from bright stars – the coma is not conspicuous in my Horsehead photo). I think the golden rule (as in software development) is to keep things as simple as possible.