I am currently imaging with an Heq-5 pro and A 130SF reflector. I utilize A DSLR and get roughly 2 minute un-guided subs, my targets of choice are nebula, and potentially galaxies. I would like to purchase the most telescope that my mount can reasonably handle, that will give me the nicest quality images. my thoughts are an Astro Tech 6" RC or perhaps the 8" version if not overly heavy for the mount. I was wondering if an SCT would be A wiser choice, say A C6, or an Edge 8, though they are quite costly. Does the central obstruction of these telescopes effectively reduce the diameter by that given amount? Are the Astro Tech RC's of good quality, and reasonable to collimate? What factors would help someone choose between an SCT or RC? Am I correct in thinking that going from F5 to F10 along with A larger aperture will increase the size/detail of A given object? I'm sure the image will be A bit darker as well, which could become an issue due to my 2 minute max exposures. What I want are the largest, clearest images I can get with this mount.