I appear to be having major issues with my 8" Edge HD scope. Attached is a screenshot of an attempt last night to see what I could do. Clearly the "donuts are pretty bad, but it appears that the position of the secondary shadow is in a completely different position for stars in different parts of the field.
Complete setup consists of the scope, a 0.7 Reducer, Moonlite litecrawler focuser, ZWO OAG and Filter wheel and a ZWO ASI1600MM Pro camera.I have double checked the spacing and the reducer requires backfocus of 105mm and with a number of spacers I have put in, it currently sits at 104.75mm.
I tried collimating a single star last night, and while I could get that star round, other stars in the field looked like "comets". Also, once a star was technically "round", I couldn't get anywhere near reasonable focus.
Any thoughts anyone?
Malcolm