[Garbz (Chris)]

I picked up a QHY10 from a forum member here (actually more of a lurker since his only posts are in the for sale section), and one of the things I wanted to use it with is an older Fastar setup. With my C8 and Fastar I should get a nice ~400mm focal length for some wide imaging.

The only problem is I can't focus. The mirror gets to the end of it's travel while the stars are still coming into focus. My guess is the spacing between the camera and the Fastar corrector isn't big enough.

Can anyone tell me what the backfocus distance of a Fastar should be? The Hyperstar says 39mm. My QHY10 is 20mm.

Can anyone confirm ~40mm is correct for the Fastar too, if so I need to order a 20mm t-threaded spacer.