Hi, I am struggling with my first imaging, and I am not 100% sure I have put everything correctly together to achieve the right back focus.
My setup is as follows: Zwo Am5 mount, WO 81 GT, WO 6III Flattener, ZWO 36mm EFW, ZWO EAF, ZWO 2600MM and Antila LRGB and Narrowband Filters.
My fist images are looking like follows: (see upload) this is with a Luminance filter
Where is the blurry ring coming from? I have done calibration frames but you can still see it in photoshop.
To achieve 55mm backfocus I have used the
I am unsure if this is correct because after the flattner the WO 81 GT is below f 5.4 ??? I have used 7.1mm as disctance on the 6III Flattener.... any ideas?
Thanks a lot
soku