|
Matty,
Crayford is defintely the go, especially a dc motor one if you have the budget.
As far difficulty in focusing, you can eliminate that by placing the flattener else where in the imaging train. Preferrably as close to you dslr as possible, as close, I mean approx 115mm from your imaging sensor. Unless your crayford focuser resembles a similar distance most people will experience difficulty in focusing when placing the flattener to the visual back of the SCT.
This way it wont matter what size focuser you use, you will always get focus and illiminate any vignetting also.
Hope this helps.
|