6 replies to this topic

[tom_halsingland]

Hello, I have a combination of Meade 8 LX10 EMC 8 inches with Baader UV/IR-cut filter, starizona sct corrector, ZWO OAG (old version) and asi294mm-pro camera. I screwed the filter in front of the corrector because I don't have a filter wheel. I processed 64 exposures with 3 minutes exposure time each, matching darks and flats with Deep Sky Stacker, but vertical shadows can be seen. I tried with and without bias, but the result is the same. What could be the problem and how can I fix it? If I were to edit the recordings with PixInsight: Is there a function that can correct these vertical disturbances? Which one is it and how should I configure it?

 

Tom. 

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[rj144]

Did you try in Siril?  I can barely see them, honestly.  If you didn't say anything, I wouldn't know they were there.

 

How about gradient correction?  Does that get rid of them?

[tom_halsingland]

Hi, click on the picture, then you see the stripes better. 

I used bin1 mode.

Tom.

[dswtan]

The 294MM demands that you use flat darks rather than bias, which can address all sorts of strange aberrations like this. You can search on previous threads. 

 

Not sure if there's a good vertical remover in PI, but external programs could address, e.g. old Topaz Denoise (not free).

[Phil Sherman]

ImagesPlus, now a free download from its author's (Mike Unsold) web site has a tool to remove the stripes. It'll do both vertical and horizontal stripes.

[happylimpet]

FITSWORK has a function called' lines to equal values', quick shortcut ctrl-z. You just have to rotate it first (one click) as it works on horizontal lines. Before and after, with contrast stretch.

 

[tom_halsingland]

Thank you @happylimpet - thats a nice tool. I had trouble with Fitsworks in combination with larger files in 32bit e.g. files with the asi6200mm. The asi294mm in bin mode has about 45 Megapixel, so hopefully it "works with the Fits". 

 

I still wonder why these stripes came out. I found that the new installed NINA plus ZWO drivers set the offset value to only 8 when using a asi294mm-pro. On other places I read that 30 would be the best value. Can it be that a too low offset could be the reason for this issue? 

 

Of course I took all files, even the correction files (flas, darks) with this offset value 8. 

By the way, the gain was 0 in this data set.

 

Tom.