[EC48675 (Euan)]

Update: after getting a new reducer from my retailer under the warranty, I've gone back out to test the new reducer. Unfortunately, the elongation is still there.

I've attached some screenshots of what the frame looks like. The first two are with 0mm added backfocus, and the last is with 6 mm extra added, since the OAG adapter has gone in by about that much on the threads of the reducer. Even adding the extra 6mm seems to have done nothing. I doubt this is caused by tilt since it is in multiple corners, and when shooting at f/10, the stars were perfect from corner to corner.

My last idea is to bring the main camera out to 133.35mm like at f/10, and see if the pattern goes the other way, indicating the sensor is "too far out", which means there has to be a turning point in there somewhere, as clearly 11mm extra wasn't enough from my previous testing.

Any and all input is appreciated!