[bluescope]

Originally Posted by peeb61

A fine bag of images there Steve!
Very nice indeed.

Paul

Thanks Paul, glad you like them.

Originally Posted by rogerg

Nice array of pics, despite the noise.

I see the pattern in the noise that you're talking about. I usually get patterns in noise when the dark frame(s) I'm using are incorrect in some way. Perhaps one dark frame for the whole night, and the camera varied temperature, so then some noise is left and other pixels subtracted, combined with some drifting in images (perhaps field rotation having an effect) ... I can imagine those kinds of factors leading to it. This would especially make sense if you were guiding on a star which is at the centre of the circle made by the ark of noise.

Short of changes to dark frames used, I would process out the noise some more by darkenning the background (and yes, perhaps losing some brightness in the objects themselves in the process) and perhaps running medians on specific colour channels to see if one in particular is a culprit.

Half this might be irrelevant depending on your camera, I can't remember what camera it is that you're using sorry.

Anyhow, nice images, just not perfect, but hey, can't be too picky

Roger.

Hi Roger

I always do darks to match particular image sets so I don't think it's due to that. I also did specific noise reduction filtering on individual channels with not a lot of improvement as the noise patterns were quite large. Anyway I'm still quite happy with the images ... as you say they're just not perfect ... and perfect is what we all strive for I think.

I use an SBIG ST2000XCM.

Thanks for your thoughts on the noise problem mate !