I am setting up an AG Optical 12.5" iHW (f/3.9 Harmer Wynne design at roughly 1250mm focal length) and I am shooting with a QHY600 along with Chroma filters. I noticed that some nights I get these nice rings around stars on the RGB filters. Some nights they don't seem to be there (or the effect is much less). Is this an issue with the autofocus routine or maybe collimation? Everything looked really nice when I verified collimation several nights ago. The stars had nice concentric rings inside and outside of focus. To me, it looks like the R filter missed focus since some of the background stars are larger compared to the B filter (it looks the same way with the G filter). The first set of pictures of from last night 08/25/2024 the second set of pictures is from the previous night (and they look much better). You can still see the faint outline of the donut in the previous night's picture.
Seeing these rings made me initially think it was the autofocus (Hocus Focus in NINA) not getting the right focus point since it looks like the donuts I got inside and outside of focus when verifying collimation. The autofocus curve is not symmetrical and looks flatter on the outside range of focus. My Epsilon is really symmetric when I run the focus curve in HF so I am not used to seeing asymmetrical focus curves.
I recently flipped my Chroma filters because I was getting some strong reflections around the stars in all filters. Once I flipped them it mostly went away. I do still get this pattern when I tried my Astronomik filter, so I don't think it is from the Chroma filters.
Any help would be appreciated!
Seeing these rings made me initially think it was the autofocus (Hocus Focus in NINA) not getting the right focus point since it looks like the donuts I got inside and outside of focus when verifying collimation. The autofocus curve is not symmetrical and looks flatter on the outside range of focus. My Epsilon is really symmetric when I run the focus curve in HF so I am not used to seeing asymmetrical focus curves.
I recently flipped my Chroma filters because I was getting some strong reflections around the stars in all filters. Once I flipped them it mostly went away. I do still get this pattern when I tried my Astronomik filter, so I don't think it is from the Chroma filters.
Any help would be appreciated!