View Single Post
Old 27-03-2013, 07:16 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
Join Date: Oct 2007
Location: Hinchinbrook
Posts: 20,211
Originally Posted by LewisM View Post
Oh, definitely not using either, though the Entropy type shows good promise for MUCH easier post-processing. I guess I will make a series of dark runs next time out, just in case I do want to try Entropy Weighted again.

In the meantime, I will continue to use Kappa-Sigma, and live with the extra dance-step of contrast tweaking

Thanks for all responses.
Look the problem is very simple but you need to understand what's going on to remedy to it one step at a time. Forget about entropy and weights and all other type of combining algos for now, it's only confusing you. They might have their own issues but that's irrelevant to the orignal problem. The bottom line is that in each subs you have bad, hot, cold pixels, defect lines or whatever you want to call them. That is a signature of your sensor and it will change with temperature and age.

These will appear in a dark, in a flat or even in a bias if it's a long enough exposure and in any sub you take with your camera regardless of the exposure time. Nebulosity is very cheap and will allow you to make a bad pixel map. If you are worried that applying darks will introduce noise to your subs (and it might well do) then don't use darks. You don't have to. I know I never used any for my QHY8. What you are interested in is where those bad pixels and lines are. So shoot 1 dark for let's say 20min at a given temperature then make a bad pixel map in a program that supports it. Nebulosity, CCD Stack also does. Then apply that bad pixel map to your subs. That will fix all of your problems and it is easy and simple to implement.

Last edited by multiweb; 27-03-2013 at 11:05 AM. Reason: spelling
Reply With Quote