Hi everyone,
Here's a weird new problem
Check out these flats I took yesterday evening.
There appear to be strange black spots that move between frames and filters.
I use a QSI wsg-8 which has the OAG prism in front of the filters.
I used the same t-shirt I always use at dusk, yes it's clean!
I triple checked the image train for obvious dust or aliens, and removed and checked the flattener, LP filter and visually checked the objective and surface of the filters. Nothing obvious there.
Thinking maybe it's a light leak or flare I removed the OAG and replaced the cap - no change. I then wrapped all connecting image train elements in dark fabric - no change.
To try to i.d. the problem, I then varied both exposure times and filters.
In order l-r these are 1 sec Ha, .05 sec C, .05 sec SII, 5 sec Ha, 10 sec Ha, 30 sec Ha, 5 sec Cyan and 60 sec OIII.
I'm guessing it's a foreign body or dust BEHIND the filters or possibly on the CCD surface?
As it's a new camera, I'm reluctant to dismantle the camera & filter wheel to access the CCD.
Not sure how to open the shutter for a visual inspection of the CCD either.
Any ideas?
Darn shame as it was a rare clear spring night in Melbourne and I've now got these marks all over my subs from the night's imaging as well.
Cheers
Andy