Quote:
Originally Posted by plasmodium
The profile of the mirror is what gives a scope its focal length/f-ratio, hence moving it won't affect either - it may give you vignetting though.
I chopped the base off my Newt, and shifted the mirror 35mm up I think I remember - prime focus with DSLR no problem now. I just use an extender for visual with EP's.....
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Ah, so you just have to be careful that the secondary still reflects the entire light cone, presumably that limits how far you can shift things. Is there an easy calculation to get the focal plane from the f ratio and physical distance between secondary & primary?