Hello,
I have searched many sites looking for similarities regarding a worsening issue I have been fighting for some time. I hope that posting here and attaching some photos will help with the diagnosis. Essentially, my stacked light frames using the Antlia ALP-T filter contains an odd ring. I use 2 other filters (Optolong), both of which do not appear to be affected. While I now use a ZWO 5 position filter wheel for 2’’ filters, the rings are also present, although to a lesser extent, on images using a filter drawer.
When I recently removed the cover of the wheel, the filter did not seem properly aligned with the opening. I thought , “ that must be the issue.” So that night, I ran the calibration for the filter wheel and the issue was still present in the stacked lights the following day. Next, as a last chance option, I took all new calibration frames. I used several different variations of exposure time to adjust the histogram on my flats and even tried using bias frames. No help there.
So, at this point I’m thinking maybe I’m dealing with more than one issue, which is making the problem harder to identify. I did clean the Antlia filter about a year ago. I usually use “Kimtech” wipes, either “Pancro” or “ROR” cleaning solution and sometimes a “lens pen.” Honestly, I don’t know if those solutions contain alcohol, but I recently read that there is an alcohol soluble layer on this particular Antlia filter. However, later I read somewhere else that Antlia listed using alcohol as a step in their suggested cleaning process. (That’s the internet for ya !)
When I look at the images, it almost looks to me like the thinner ring on the righthand side is the clean part of the filter and the rest has some sort of varying haze over it. Maybe its the coating I’ve diluted when cleaning if any of that is true ? As far the filter wheel possibly shifting even after calibration, I don’t know. I’m relatively sure, that in order to balance the wheel, I installed the 3 filters, with Antlia on one side and the other 2 on the opposite, since the Antlia is a bit heavier. I will check into that. I also believe the Antlia filter is a few mm’s thicker than the Optolongs, but that shouldn’t affect back focus or the stacked image when using an auto focuser, correct ? All filters are mounted.
Any opinions or a nudge in the right direction would be helpful. Up till now, I’ve managed to process out most of it. However, it appears to be getting quite a bit worse or that some other variable changes the severity of the problem at different times.
I’ve done an ABE, simple stretch and NXT for clarity. Example 1 is the newest. Example 2 is a year older, and was taken using a filter drawer.
What say ye ?
