[Atmos (Colin)]

As there are a good number of DSLR astrophotography enthusiasts on here, I figured this would be the best way to get an answer.

I have a Nikon D700 that I mostly use for daytime photography but I am wanting to do some wide fields with it now that I have a way of nicely connecting it to my old HEQ5. What I am wondering is, as it is uncooled, whether doing 5m exposures will be more problematic than it is worth.

I was doing some testing tonight and after some testing I have come to realise that I need to use my 50mm lens at F/7.1 to get reasonably good stars over the whole FX frame. Some back of the envelope calculations suggest that at this I am best using 300s (5 minute) exposures. I know that if I do not sufficiently get close to sky limited with my camera I get terrible banding that cannot be processed out so I do need to overwhelm it.

What I am curious about is whether the dark current (thermal) is going to start being more of a problem than I might imagine it to be?