1.5" vs 2" upgrade for SCT

[Luna-tic]

Is there any advantage to either viewing or imaging to change my 1.5" visual back to a 2" visual back, and then having the option of a larger diameter Barlow and diagonal, if I plan to keep 1.5" eyepieces? I read something about restricting the light cone at the visual back and it serving to dim the view, or  having to increase the exposure times or ISO for imaging, versus having a larger diameter in that area. I have at present a C6. Should I just save the dinero and stay with 1.5" all the way to my eye?

I'm planning to upgrade the star diagonal at any rate, just need to know which size to look at. I have seen a couple that thread directly to the rear cell rather than clamp to a visual back. I like the idea of the security it offers, but won't that preclude putting a Barlow in there? Skewing clearance there doesn't matter, I have a GEM rather than a stirrup Alt-Az.

[Peter Drew]

The main advantage of a 2" fitment for SCT's less than  8" is the better load capacity. A 2" diagonal with the screw fit to the rear cell doesn't preclude the use of a Barlow as this fits into the eyepiece side of the diagonal.    l