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Help - Focuser Replacement

Started by DaveKG, 08/10/2005 02:28PM
Posted 08/10/2005 02:28PM Opening Post

I could use a little help in recommendations on replacing the focuser on an 8" Meade Starfinder. Here are the details.

The current focuser is approx. 3" racked in and 5-1/4 racked out. I have a 2" hole in the OTA, but will be using primarily 1.25 eyepieces, so the adapter will be in place. I think it would be best for me to try to match the length of travel as much as possible.
I am considering a Crayford design, although the budget would probably demand that it be a used focuser or a great sale somewhere.
Is there anything that particularly shines or anything to shy away from in the Crayford category? JMI - RCF1 - reverse Crayford, Scoptronix, Rigel, Burgess, SmartAstronomy

Last, but not least, if I would stay with a R&P, what recommendations would you make there?

Thanks,

Dave
Posted 08/10/2005 03:34PM #1
The stock focuser was pretty tall.

The replacement Crayfords are comparatively short.

This means you will need to move your mirror further down the tube (toward the back of the tube). Luckily, this is fairly easily accomplished--at least in my experience with a 10 inch Starfinder EQ. I heard the dob mounts were different, but I could not tell you exactly how. In an EQ version, one just drills three more holes a little further back (actually, as far further back as the new focuser is shorter than the old--and that varies with just what you need in your own eyepieces), and re-bolts the cell lower. THere was enough room to handle this on my mount.

The secondary did not need changing, as far as I could tell.

Alex
Posted 08/11/2005 09:34AM #2
Is there anything that particularly shines or anything to shy away from in the Crayford category? JMI - RCF1 - reverse Crayford, Scoptronix, Rigel, Burgess, SmartAstronomy
====

As others have said, getting the proper height is the real issue. I believe that JMI can provide custom length focusers, some specifically designed to replace the Meade focusers.

If you want to go the inexpensive route, OPT has some 2 inch R&P focusers for $20. Never seen one but OPT was selling GSO DOBs (same as Hardin) and the OPT DOB I have has decent focuser, significantly better than the Orion/Synta Focusers I have owned.

jon