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I use a Vixen VC200L with dedicated 0.71 reducer to make it f6.4. The standard focuser is a very smooth minimal backlash single speed rack and pinion but it has no camera rotation. The eyepiece holder unscrews and the reducer screws straight into the main R&P barrel so the camera is very solidly attached. No slop. There isn't a huge amount of back focus and the camera fits directly to the reducer via a T ring so the camera train is very solid. The reducer has a thread lock on it that I think is supposed to act as a rotator but I don't find it easy to use.
I can't easily put a rotator in the train as it will mess up the spacing/mounting.
To work around the problem, I recently purchased several T rings for the scope and have preset the T-ring rotations on the 4 adaptors at 4 different angles. Changeover is very quick.
This is not as convenient as a rotator but it is pretty quick and i find these 4 angles are adequate for my composing. Next I am going to use my dremmel to engrave them with the designations:-
. V- vertical. (long axis of frame parallel to Dec axis)
. H-horizontal (long axis of frame orthogonal to Dec axis)
. 45 R / 45 L for left and right tilt from vertical
Joe
Amateur astronomer since 1978...................Web site :http://joe-cali.com/ Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80. Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's. Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12 Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec. Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members), The Sky Searchers (moderator)
JayTee wrote: ↑Tue Jan 18, 2022 10:34 pm
I know this sounds like a silly question but can you rotate the entire OTA?
Hi JayTee
No, The dovetail rail is screwed into the tube, mirror cell and spider ring. Would have to remove it and put tube rings on. The tube handle would probably have to be cut off as well. In this photo, the handle is part hidden by the finder.
I usually mount the OTA with the dovetail as far forward as possible and that's with a 1kg tube weight on the dovetail at the front. Centre of mass is under the mirror with 700g camera attached so using tube rings isn't going to work very well.
Joe
Amateur astronomer since 1978...................Web site :http://joe-cali.com/ Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80. Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's. Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12 Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec. Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members), The Sky Searchers (moderator)
