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Equipment Discussions >> Mounts

Pages: 1
MattT
sage


Reged: 04/20/06

Loc: SF Bay Area
Rings 'n' Rails
      #5785924 - 04/08/13 12:50 PM

A mounting ring purchase may be in my future. I just bought a vintage Meade 127ED, f9 doublet, which if you believe the USPS tracking data should be delivered today or tomorrow. It's coming with the unusual Meade cradle-rings that bolt to the old LXD mount these OTAs were usually sold with. In photos it doesn't look like the cradle will be easy to adapt to a Vixen or Losmandy style dovetail rail. And even if it were, that cradle looks massive and I'd like to save as much weight as possible, since I'll be trying to get by with the scope on my SVP at least until I'm sure I'm going to keep it awhile.

So....is there any functional difference between the undeniably beautiful, hex- or octagonal machined rings, and the cast aluminum rings that sell for much less at, for example, Scopestuff?

And is there some formula for how far apart rings should be spaced along an OTA? For example, 2x the diameter of the OTA or something like that? If I have to buy a new rail I want it to be adequate, but minimal weight.

Thanks and clear skies!


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dmdouglass
professor emeritus


Reged: 12/23/07

Loc: Tempe, AZ
Re: Rings 'n' Rails new [Re: MattT]
      #5786051 - 04/08/13 01:30 PM

Spend some time browsing here:

http://admaccessories.com

It will be well worth your time.
AND...
Be sure to acquire all parts in "Dual Configuration", meaning dual D and V.

Nuff said!

Edited by dmdouglass (04/08/13 01:32 PM)


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jrcrillyAdministrator
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
Re: Rings 'n' Rails new [Re: MattT]
      #5786118 - 04/08/13 02:11 PM

Quote:

So....is there any functional difference between the undeniably beautiful, hex- or octagonal machined rings, and the cast aluminum rings that sell for much less at, for example, Scopestuff?




Yes. It may not make much difference for visual use, but better rings will always improve imaging performance. There are three general classes: formed rings (as in Scopestuff), cast rings (such as Parallax), and machined rings. I much prefer the machined rings in the sizes they are available. For larger rings, the cast rings are better than the formed rings.

For plates, I agree with the above ADM recommendation.


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MattT
sage


Reged: 04/20/06

Loc: SF Bay Area
Re: Rings 'n' Rails new [Re: jrcrilly]
      #5786157 - 04/08/13 02:32 PM

OK, thanks. Per the Meade manual the OTA diameter is 135mm or ~5.3"; in my limited shopping so far Scopestuff is the only vendor that stocks the size. I'll wait till it gets here and double check diameter before ordering.

Maybe I can bother a friend with a drill press to help me mount the appropriate rail right to that Meade cradle, weight be darned. I think an Atlas mount is in my future...


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jrcrillyAdministrator
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
Re: Rings 'n' Rails new [Re: MattT]
      #5786244 - 04/08/13 03:40 PM

Quote:

Maybe I can bother a friend with a drill press to help me mount the appropriate rail right to that Meade cradle, weight be darned.




I did that with the cradle of a 178ED; worked great. I wasn't worried about ring weight with a 40 pound tube, though!


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jrcrillyAdministrator
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
Re: Rings 'n' Rails new [Re: MattT]
      #5786250 - 04/08/13 03:44 PM

Quote:

OK, thanks. Per the Meade manual the OTA diameter is 135mm or ~5.3"; in my limited shopping so far Scopestuff is the only vendor that stocks the size.




It is an odd size. I've been known to pad larger rings with an extra layer of felt...


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MattT
sage


Reged: 04/20/06

Loc: SF Bay Area
Re: Rings 'n' Rails new [Re: jrcrilly]
      #5792517 - 04/11/13 02:31 PM

The scope is here, and it looks beautiful. My first big refractor....I've wanted one of these since I first saw the ads in S&T almost 20 years ago.

I need to go to the store for some hardware but it looks like there should be no trouble bolting a short rail that I already have to the factory-drilled holes on the cradle. But the weight....the cradle alone is 4.1 lb and with rails and hardware will be around 4.5! I've had whole scopes lighter than that. What a strange design choice by Meade. Hopefully the SVP will at least allow me to get a sense of how the scope performs. I emptied the slush fund for the OTA and will need to wait a while before upgrading the mount.


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MattT
sage


Reged: 04/20/06

Loc: SF Bay Area
Re: Rings 'n' Rails new [Re: MattT]
      #5879507 - 05/23/13 02:01 AM

Well after being delayed by a lot of personal and family stuff I finally got to look through the scope this evening, for the first time. Seeing is poor but the Moon looks pretty good, clearly more detailed than in the 80mm I was using last night.

I wound up buying a set of cast rings and a cast dovetail from Agena. Together they saved, according to the kitchen scale, about three pounds compared to the Meade cradle + a short dovetail rail. And, the new parts hold the OTA's center of gravity about an inch closer to the RA axis. With the Agena rings and rail I can get by with 14 lbs of counterweights, and the scope actually seems to ride pretty well on the Skyview Pro, for visual work at least. Damping time is around a second and it's steady enough for focusing by hand, barely.

Thanks for all the tips....I'm going out again now to see if the seeing has gotten any better!


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