[stephen2615 (Stephen)]

Greetings,

I have a reducer/flattener that requires 54.8 mm back focus. My new QHY 16200A CFW7 with an OAG cannot make that distance at it accounts for 54.5 mm. The flattener has a thread of about 5.7 mm. The adapter that attaches to the front of the OAG is 3 mm thick. That means there is going to be a discrepancy of 2.7 mm too long on the flattener but about 0.3 mm can be made up with the 54.5 mm imaging train distance.

So assuming you have not nodded off with those numbers, would a 2.4 mm discrepancy be a disaster for a flattener? Should I just ditch the OAG and get a better guide scope?

Cheers

Stephen