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Tim Laswell
newbie
Reged: 02/08/07
Posts: 3
Loc: MD, USA
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I have a 4.5" Newt I paid very little for. It came with what turned out to be a .965 eyepiece holder built into a T-ring adapter over something like a 1.65 inch focus tube. This focuser was long, like 3 inches. I recently purchased a Meade 07345 #70 R&P. It is about 1/4 inch too short. Fully extended I have to keep most of my eyepieces out a bit. This focuser has a ring threaded on the end as an eyepiece holder. Does anyone know if Meade made an extender that would screw into this? I only need 1/2 inch or so.
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spaceghost
super member
Reged: 01/04/07
Posts: 139
Loc: Olathe, KS
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Hi Tim! You could try tightening the collimation bolts all the way, which will move the primary backwards. Maybe there's enough room on the bolts to get what you need. You can also try reinstalling the mirror cell further back in the tube.
Welcome to Cloudy Nights!
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Justin
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Biff
Carpal Tunnel
Reged: 09/04/05
Posts: 2253
Loc: Courtice, Ontario
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What Justin said, hopefully there's enough threads left in the collimation bolts.
Best case would be to rebuild the tube and make the distance between the primary and secondary a bit longer so the focal plane (point of focus) is closer to the secondary. That has a couple advantages and hey it's an excuse for an ATM project... I know we're all looking for some sort of excuse  .
Lastly you could get an old cheapie barlow (which you could probably get near free) and just unscrew the optics to use as a sort of extension tube, but that would get you about an extra 1.25" or thereabouts so it may be too much.
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Ryan
Antares 200mm f/6 Dob & 130mm f/5 Travel Dob.
Projects on the go...
- a couple 80mm SS refractors on the back burner.
- a few small mirrors awaiting polishing
- 260mm f/7.15 mirror... still polishing
Member of DRAA
 My house.
 DRAACO
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Tom and Beth
sage
Reged: 01/08/07
Posts: 429
Loc: Tucson, AZ
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If you can't get enough range out of the collimation bolts, can you move the mirror cell back a 1/2 inch?
Total failure mode on either of these....go to home depot and pick up a drain pipe. The ID is a slip fit for a 1.25 inch EP. Cut off what you don't need.
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Tim Laswell
newbie
Reged: 02/08/07
Posts: 3
Loc: MD, USA
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I thought of the colimnation bolts, for the most part the cell is flat up against the tube. Letting them out may give me a little relief. I haven't checked the colimination since I installed the new focuser. After seeing the pictures I took with my Star Shoot Solar System camera I probably should. I'll check if the bolts are long enough. I'm not messed with this bolt and lock bolt design too much. The spring on bolt design of my Orion Dob is a lot easier to work with.
I like the throw away barlow idea better, that way if I need to shorten it again (to attach a DSLR) I can easily remove it. If I'm lucky the barlow would have a better compression ring.
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