Finding your target

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Andy Wilson

Hi John,

I’ve also had this problem. I found that not only the mounting, but also the focuser and mirror flop caused problems. I’m not sure whether you have an extra focuser for fine focusing your C8. I used a Crayford focuser on a 14″ Meade for fine focus without moving the mirror. The weight of the spectrograph and 2 cameras caused the focus tube to shift as I slewed, making it nearly impossible to point accurately.

I am using a different setup now (10″ F8 RC) but I found several points that could help you, 2 already mentioned by Andrew and David.

– If you can afford to setup an electronic finder scope then that can be a big help. Otherwise just a good finder so you can easily and accurately point your telescope to bright stars.

– Star hopping from nearby bright stars. Start off with an obvious bright star on which to sync your telescope. Then jump to bright but progressively fainter stars nearer your target, re-syncing your telescope on each star, until you reach your target.

– I used a flip mirror between the spectrograph and telescope so I could use an eyepiece to check where the telescope was pointing. I found this was a big help but not without its difficulties. I could just about get it so the spectrograph and eyepiece were in focus at the same time. A couple of things to bare in mind. First, this moves the spectrograph and cameras further from the back of the telescope, increasing the moment arm on the telescope and mounting. Second, if you use a Crayford or Rack and Pinion focuser for fine focus then this increases the strain on the focuser.

I would expect finding objects to be much easier with your 80mm refractor as the field of view will be larger. As long as the focuser and mounting are up to the job.