Just joined the forum, although I've been reading and learning from a lot of posts to this forum over the last 6-9 months. I have a bit of a challenge that I'm facing. I'm pretty new to astronomy, although I've been an occasional night sky viewer when important stuff was going on (Hale-Bopp back in 1997, and fascinated by Shoemaker-Levy impacts on Jupiter back in 1994). Finally had time to actually try to capture images of NEOWISE last summer with a Nikon 850 DSLR using 30s images (by hand) on a tripod, which got me interested in trying to look at more things in the night skies. Decided to buy an actual telescope later that year for the grand conjunction of Jupiter and Saturn (but of course up here in Michigan we had cloudy skies).
Not knowing how long this interest would last (and not knowing really what I was doing), I bought a fairly cheap 4" Newtonian reflector telescope on an equatorial mount from Solomark, which at least for the refractor has been okay. I quickly realized I needed a motorized mount if I was going to be able to do anything interesting (or at least, realized the non-motorized mount they'd provided was not workable for anything other than staring at the moon... and even that was hard to track properly with the rudimentary DEC and RA controls they had). So I upgraded to a SkyWatcher EQM-35 Pro motorized mount (again, being a bit conservative in how much I was spending because I didn't know if this was going to be something I stuck with long term or not). I also realized if I wanted to see anything interesting with the 4" reflector telescope I was going to have to collect light for a good amount of time, so I started building some cameras onto the telescope. Eventually, I ended up with a 50mm guide scope with a ZWO ASI 120MC camera on that and a ZWO ASI 183MC Pro in prime position on the 4" refractor, with everything controlled by ASIAIR Pro and an iPad to run everything. Once I figured out how to integrate everything this led to a lot of fun imaging over the last several months.
Now to the problem. The Solomark reflector I'm using was clearly not designed to use cameras instead of relatively short focal length eyepieces. I've been using a 2"-1.25" adaptor from ZWO to fit this on the telescope, but during the summer (warm weather) I basically had to adjust the focus all the way to the shortest possible focal length to bring images into focus on the camera's CMOS chip. Now that the weather has gotten colder, this no longer suffices. I am close to bringing the CMOS chip into focus (I can see a small bright disk for bright stars and can observe the secondary mirror and spider struts, but cannot get the image in focus. Based on earlier focusing I'm guessing I'm around 2-3 mm out of focus onto the CMOS chip of the camera. The Solomark reflector does have a removable 1.25" eyepiece mount, that unscrews from the focusing rig that looks way thicker than it needs to be (see attached photo), additionally, the ZWO ASI 183MC camera has a T2 extender (see attached photo ) that adds about 11 mm of focal length to the CMOS chip of the camera.
What I'm wondering is if there are any cheap solutions to either replacing the thick 1.25" adaptor that screws into the focuser, or a slimmer T2 adaptor that attaches to the M42-M48 adaptor to the ZWO ASI 183MC cam? This all may be a bit moot, because I finally pulled the trigger on a WO 91mm FLT refractor which should arrive soon, and to which I'll mate the ZWO ASI 183MC camera and the associated 50mm guidescope and camera. But I'd really hate to not have a solution to this focus issue with the Solomark reflector scope, in case I decide to use it again (maybe as a second imaging scope on good nights).
Any suggestions would be greatly appreciated...
Edited by JustErik, 26 September 2021 - 09:33 PM.