I wanted to ask what the recommended Backfocus for my 8" f/4 scope (native) with the ASA 0.73x reducer is - I don't find documentation for this on any of the pdfs/drawings. Doesn't it perfrom well with a 8" or what's the reasoning behind this?
I can get down to an absolute minimum of 66.3mm which I fear is too much (basing on numbers for a f/3.8 system and different mirror sizes). Filters would add 0.7mm to the BF of the reducer.
ASA 2" .73 Back Focus for 8" f4.0 (800mm) Native Newt
in ASA Correctors & Accessories
Posted
Hello,
I wanted to ask what the recommended Backfocus for my 8" f/4 scope (native) with the ASA 0.73x reducer is - I don't find documentation for this on any of the pdfs/drawings. Doesn't it perfrom well with a 8" or what's the reasoning behind this?
I can get down to an absolute minimum of 66.3mm which I fear is too much (basing on numbers for a f/3.8 system and different mirror sizes). Filters would add 0.7mm to the BF of the reducer.
Any help is much appreciated!
Best,
Tim