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ASI1600 Weird pattern on Oiii flat

Posted: Sat Feb 09, 2019 10:22 pm
by nexusjeep
Hi,
I have an ASI1600MM Pro and have noticed a weird pattern on the Oiii flat I have rotated the camera independent of anything else and the pattern does not move. So my assumption is that it is either on the inside of the cover class as I have cleaned the outside or it is on the cell cover glass, it only appears to show on the Oiii flat.

I have included one image for the Oiii below as well as the one from the Ha for comparison these are massively stretched to get them to show up and in reality the pattern calibrates out when processing the image I was just wondering if anyone else had seen the same thing.

Cheers
Nick

Re: ASI1600 Weird pattern on Oiii flat

Posted: Sat Feb 09, 2019 11:46 pm
by oopfan
Do you have the OIII filter loaded in a filter wheel that remains stationary when you rotate the camera? If the filter is screwed into the camera nose then it is mostly likely the filter.

You might want to send these snapshots to Sam at ZWO. It could be that condensation has formed on the inside of the sensor window. More likely it is something on the outside. Use a bright light and high power magnifying glass. What are you using to clean the window and your filters?

Brian

PS: Oh OK, I see your telescope photos now. You've got a ZWO filter wheel. Never mind.

Re: ASI1600 Weird pattern on Oiii flat

Posted: Sun Feb 10, 2019 9:37 am
by nexusjeep
Hi Brian,
I will try emailing Sam as I don't think it is condensation as I can image fine and it only appears to show on the Oiii flat it has probably always been there it was only the fact that I decided to actually study a flat that I noticed it which was probably a mistake as ignorance was bliss. I have cleaned the outside of the window with Zeiss lens cleaning solution and lens micro fibre so assume it has to be internal and as you spotted the filter is in a ZWO wheel so it has to be something in/on the camera.

Also as I say it calibrates out fine on the actual images so is not technically an issue I was just bemused to the actual cause, as I say I will drop Sam an email to see what he thinks and post his response once I get it in case anyone else sees the same thing.

Cheers
Nick