They are also optomized for the shorter light path of smaller diagonals. The further you move the eyepiece back the longer the e.f.l. with an SCT and the more the optical deficiencies show up.
Absolutely. I have a Baader T2 on mine as it is the shortest path - made a noticable difference.
Using a 2" diagonal actually increases wavefront error.
I threw on a 2" Diagonal once for kicks and it just threw the whole scope out of balance. But i like to use the big and heavy Nags or may want to use a Ethos here and there. These heavy eypieces are hard on the fork mounted C5 as it is tail heavy even with 1.25" stuff. I just bought some tube weights and clip to help with balance.
Edited by CHASLX200, 18 February 2018 - 07:43 PM.