|
Simon, in years gone past I have found that the secondary needs to be off set away from the focuser (as you have said) but also it needs to be moved towards the primary as well. If you draw the light cone to scale within a drawing of the OTA you will easly be able to measure these 2 off sets.
I also found that standard collimation techniques did not work with a very fast astrograph.
If you could give me all the measurements I can have a look for you.
Dave
|