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My gear: --Celestron 8EdgeHD & 11EdgeHD | 80mm F/6 Triplet | Modified Canon T1i | QSI683WSG-8 | QHY5L-II | Celestron AVX mount | iOptron CEM60 mount | iOptron ZEQ25 mount --- My skies:
Uncle Rod Uncle Rod's Astroblog: http://uncle-rods.blogspot.com/
Quote:Also, and possibly related, when calibrating with PHD, I get the movement along the N axis, but it fails to return very far at all doing the S calibration.
Scopes: 12.5" dob w/Lightholder mirror, Astro Tech AT8RC, TPO 8" Imaging Newtonian, Intes MK-67 Deluxe, Takahashi FS-60CB, Tasco 10TE, Coronado PST
Mounts: Celestron CGEM, Celestron AS-GT
Eyepieces: Pentax XW 30, 20, 10, 7
My images: http://mtanous.wordpress.com
Astrophoto: Intes Micro ALTER-M606 (6" f/6 MCT), Astrotech AT6RC (6" f/9 RC), 2x Tair-3 lenses (300mm f/4.5)
Visual: Celestron 8 SCT ('77 Orange Tube, 8" f/10), Selsi #247 Refractor (aka Towa #339, 80mm f/15), Tasco 11TE-5 Newtonian (4.5" f/7.9), Galileoscope (50mm f/10)
Mounts: Celestron CI-700, iOptron ZEQ25GT, Celestron CG5-ASGT, plus a couple old EQ2s My Astrophotography Site: http://ap.x-wing.ca/
Quote:Yes absolutely sticktion can and does cause that sawtooth - it certainly did with mine! I took mine apart and re-greased it and it reduced the problem quite a bit. The guiding in one directly only trick also helps a lot.Ultimately I had my best CG5 guiding results when I had several imaging nights in a row and left my equipment set up each day. Each night I slightly improved the polar alignment and by the last night the polar alignment was so good I was able to turn DEC guiding off entirely and only guide in RA!(The lesson of course being to learn from my mistake and spend moer time on the FIRST night doing drift align or multiple iterations of the ASPA function)Oh, and a hypertune service like DeepSpacePoducts may help as well if you have spare $$ as he not only does re-grease but also adjustments and polishing of bearing surfaces.
Quote:[I don't doubt that stiction could cause this, but I do have a strong suspicion that cogging occurs in the CG5 as well.
Quote:Well, I learned a whole lot by taking the motor cover off and watching what is happening.
It turns out that if the declination backlash settings are high, at least on my mount, the motor will make an initial big leap, and then do nothing for a while. However, at smaller backlash settings this does not occur. I have moved my backlash settings back down to 5.
I don't know if this will help with my sawtooth behavior when guiding or not.
I suspect not, unless in fact it is switching directions. I don't think that is the case. But either way, this needed fixing.
Watching the motor, I do not think I am seeing cogging, at least as I have seen it described.
Quote:Also, and possibly related, when calibrating with PHD, I get the movement along the N axis, but it fails to return very far at all doing the S calibration. Again, I thought that was being caused by weight balance issues, but that does not appear to be the case. I have tried up backlash settings to around 30, but that does not change things.