[MrB (Simon)]

Originally Posted by turbo_pascale

....

If you get the CCDCalc program, you can see what the critical focus zone is for a particular scope combo will come out like.

http://www.newastro.com/newastro/boo...camera_app.asp

....

Turbo

A HUGE thankyou!
I used a simple program like this years ago, then had a harddisk die on me but couldn't remember the programs name or where I got it.
Maybe this is it and it's gone through a few() changes since I last had it?!