I shoveled the snow off the back driveway this evening to take advantage of a relatively clear night, and rolled out Big Bertha. Not being a motorized (or even motorizable) mount, taking astrophotographs with it is a bit optimistic, but I thought, maybe I can take some decent pictures of the Moon--it's bright, and Big Bertha has lots of aperture.
1. I couldn't do prime focus photography (where you use the telescope as the lens). The focal point of the mirror is too close to the end of the eyepiece focuser, and I can't get the focal point inside the bare camera body. This may be an argument for a lower profile focuser.
2. If I put a 3X Barlow lens in the focuser, it moves the focal point far enough out to get in focus--but just barely, and at the least inward travel of the focuser, it is too stiff to get an even slightly acceptable focus.
3. With eyepiece projection (telescope plus eyepiece combined to form a lens), I was able to get in focus--but the roughness of the focuser still means that the images I captured weren't very sharp.
Click to enlarge
Click to enlarge
Some of the grain you see is the combination of setting the "speed" to ISO 1600, and getting a little too aggressive with the sharpening filter in my computer.
I have not been completely happy with the focuser that came on Big Bertha because of an inability to get a sharp focus. If I had sufficient inward travel to do prime focus astrophotography, I would buy one of the helical fine focus inserts for it instead. But perhaps getting a lower profile focuser (which would almost certainly a smoother and finer focus as well) would be worth considering.