It should reach focus just fine. By not reaching focus, do you mean that you lack "in" travel? Or by "back focus" do you mean that you can't rack it out far enough? No extension tubes? For small objects like M57, you don't need the 2" format. You could go 1.25" and use eyepiece projection to get any image scale you like. I have a similar problem with image scale on my 80mm refractor, used at prime focus. My solution is what you suggested, I use the C6 instead. Gives me over 3X the focal length. On Sat, Aug 10, 2013 at 12:45 PM, Dave Gary <davegary@me.com> wrote:
Ring Nebula, M57. This has no more detail than viewing this feature visually through this scope. I couldn’t get any more detail because I wasn’t willing to invest the increased time on the exposures. These images are 4-minute exposures. You can see the mount was off a little. I kicked the mount by mistake while doing a fine focus. So much for good polar alignment. I don’t have an electric focuser for this little refractor. Wish I did. One question for anyone who knows or has experience with refractors: Does someone make a two-inch Barlow for a refractor that would allow the refractor to reach focus? I have a Zhummel 2-inch ED Barlow, but I do not have near the back-focus with this setup. Not even close. Is the solution, merely, to switch to the Schmidt-Cassegrain to use a Barlow? I don’t have enough experience with these things to know. I really like the little refractor for the tack-sharp focus (well, tack-sharp if you don’t trip over the tripod legs on a regular basis while acquiring an image). However, I’d like to have a slightly magnified image going to the CCD chip. What’s the solution? If this is a really stupid question try to suppress the laughter long enough to e-mail me back and tell me this is a really stupid question. Ask Patrick or Chris, it’s nearly impossible to hurt my feelings.