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Author Topic: Celestron CG-5 backlash limits  (Read 63 times)

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Offline mikejenningz

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Celestron CG-5 backlash limits
« on: 15:00:55, 07 December, 2017 »
I have quite an old celestron cg-5 mount and in recent times I’ve noticed declination backlash becoming worse and worse.  For my seteup  I use a 400mm focal length refractor guide scope attached to the mount with a QHY5 guidecam.  I do DSLR astrophotograhy with a main scope being celestron 8” SCT.

  I often try for as long sub-length as I can on feint targets.  Auto guiding does seem to be affected by excessive backlash anytime the guiding direction needs to change or until the mount settles when I start guiding.  I don’t mind polar alignment being off a little to encourage DEC guiding to stay in one direction.  I use PHD2 software to guide and this can measure backlash by number of pixels which is quite useful.  I’m getting between 20-25 pixels currently, however before my latest tweaks as was up to 55 pixels and the mount was really terrible.

This weekend I am planning to remove the dec housing again and try and improve the gear meshing.

  I’m curious to know what size of backlash you get and is 20-25 pixels an acceptable amount or should I expect much better.
I guess either way, I’ll have to endure it, until I can afford a new mount.  (Shopping list already written celestron CGEM, and 11” SCT).  But until then I hope to keep the old CG-5 on the road. ;)

Mick.

 

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