Why is my DSLR producing smooth islands?!

[Fordos Moon]

Morning all. I have been having enlightening conversations with Ivo Jäger (StarTools) and he has been very generous with his time trying to help me solve this problem.

This is the kind of image I am getting pre-stretching using Deep Sky Stacker 3.3.3 beta 51. As Ivo has pointed out to me my data has no noise grain at all but has large smooth islands so something has quantised or filtered my data leaving us nothing to tease out in terms of detail.

Any suggestions would be most appreciated!!

Bob

[jager945]

Just a small correction, this is post-stretching (mildly). Bob and I have been wracking our brain, trying to figure out why his stacked image appears smoothened or quantized. He says he's stacking CR2 raws, not JPEGs (confirmed) and is saving the resulting stack in 32-bit integer format.

You'll notice the absence of any noise, as would be expected from a DSLR stack, instead showing a smoothened (median filtered-like) image with clear 'strata' or islands of equal brightness pixels where a level of random noise would be expected instead....

[Fordos Moon]

Thanks Ivo, stand by later to receive the CR2 files if I can manage it!

[rfdesigner]

Can you post a single RAW frame please.. in JPEG form after adjusting levels say, so we can see what you're starting with.

(not only am I noticing absence of obvious noise.. but also absence of stars etc., huge levels of smearing, I want to see if a single sub is sharp or not)

Derek

[Fordos Moon]

Can you post a single RAW frame please.. in JPEG form after adjusting levels say, so we can see what you're starting with.

(not only am I noticing absence of obvious noise.. but also absence of stars etc., huge levels of smearing, I want to see if a single sub is sharp or not)

Derek

Thanks for your offer to help, sorry for delay I have been away, i have attached two jpegs from single raw (CR2) frames one stretched and one not which will hopefully give you enough to let me know what I am doing very wrong!

[davew]

You've not got the cosmetic hot / cold pixel filter wound right up have you ? Even if it's set very low, try stacking without it.

Best guess !

Dave.

[rfdesigner]

I don't know how DSS does hot pixel removal.. ideally you only work out where your hot pixels are from a dark frame.. never a light.

I'd want to try stacking without hot pixel removal or to create a hot pixel map from a dark frame.

Derek