[RobF (Rob)]

Apologies if this has been done to death before, but I'm curious to hear people's recommendations on preferred ISO for imaging DSOs. I'm usually working from city skies with a light pollution filter (Hutech IDAS) and auto-guiding.

I've wanted to get out and experiment, but time and weather haven't allowed of late. From my very limited experience to date 1600 always seems too noisey for darks/flats to tame. 800 with max subs of 5-10 mins seems more realistic for my skies?

From the bit of reading around I've done higher ISOs are basically doubling the amp gain on the imaging chip. Supposedly there is some risk of losing dynamic range at 1600, but unlikely to be a problem for most objects.

Any comments/experience appreciated....
(but no prompts to go and buy a CCD please!)