Quote:
Originally Posted by RobF
The other major practicality in all this of course is trying to get a decent number of subs for stacking. Most stacking rejection algorithms get better as you have more subs. I don't like having less than 7, but preferably many more, for each filter.
So if you're shooting LRGB with a mono camera, that means you need the object to be reliably visible for 28 times your chosen sub length for the period you have available. Most of us with portable rigs are often scrounging 1 to 2 nights maximum at a dark sky site. Nothing worse than setting out with best intentions then having cloud or weather intervene. You may have maximal SNR L,R and G but it ain't going to amount to a nice image until next year perhaps when you manage to get the long Blue subs you missed out on 
Does anyone set out with a target number of subs you feel you need to collect, in addition to the important requirements of SNR? |
that's a good point. Lately I have been using an incremental approach - baseline is 30 subs lum and 15 each colour then add subs in increments of about 15 lum and 5 for each colour until the image is deep enough - although lum takes extra precedence if the seeing is good. SGP makes this sort of approach dead easy, by automating everything and keeping track of where the process has got to.
edit: Slawomir just beat me to it - snap!