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Super Polaris Celestron C8 and CGEM mount

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#1 MarshallCrenshaw

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Posted 18 March 2013 - 10:35 PM

I have a Super Polaris C8 scope which I believe has a Vixen dovetail mount (1 3/4 inch wide and 7 1/2" long bar on the Super Polaris mount, with shorter female on scope). I am getting a CGEM mount.
Am I correct that the CGEM mount has a different size of dovetail? What do I need to do to mate the two?

#2 jrcrilly

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Posted 18 March 2013 - 10:53 PM

The SP-C8 mounting was "upside down" compared to what is usual today. The modern mount has a saddle (female) on it, and a dovetail plate (male) is installed onto the optical tube. Suitable dovetail plates are available from ADM Machining.

#3 rmollise

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Posted 19 March 2013 - 08:07 AM

Yes. You need to replace it with a Losmandy D Format dovetail (Losmandy, ADM, etc.)...

#4 mclewis1

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Posted 19 March 2013 - 09:21 AM

Marshall,

Or replace the saddle on the CGEM with an ADM dual saddle which is of better quality than the original and can handle both types of dovetails.

Changing the dovetail bar on your scope is a little less expensive, but changing the saddle on the mount is the more flexible solution and if you're considering other scopes in the future could be the least expensive in the long term.

#5 jrcrilly

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Posted 19 March 2013 - 09:37 AM

Changing the dovetail bar on your scope is a little less expensive,


There's no dovetail plate there now, only a saddle (the SP-C8 isn't like modern gear). His only options are (1) install a Losmandy-compatible dovetail plate to fit his mount, (2) install a Vixen-compatible dovetail plate and modify the mount to fit by replacing its saddle, or (3) use a dual-male Vixen-style plate to go between his optical tube's saddle and the saddle of a modified mount. There might be a 4th possibility if anyone makes a male-Vixen-to-male-Losmandy adaptor plate to link his saddle to the mount's saddle. Adding a Losmandy-style plate to the telescope to fit his mount will be the easiest option.

#6 rmollise

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Posted 19 March 2013 - 11:15 AM

Marshall,

Or replace the saddle on the CGEM with an ADM dual saddle which is of better quality than the original and can handle both types of dovetails.

Changing the dovetail bar on your scope is a little less expensive, but changing the saddle on the mount is the more flexible solution and if you're considering other scopes in the future could be the least expensive in the long term.


No...he'll have to change the dovetail on his telescope either way, muchacho...

#7 MarshallCrenshaw

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Posted 21 March 2013 - 06:57 PM

I decided to get the new dovetail plate to mount on my scope. I got a "Dovetail plate to mount 8" Celestron optical tube on Celestron and Losmandy mounts" from Astronomics for $32.95. Removed the old saddle and used those screws on the dovetail plate on one end - needed another screw for the front end and had to borrow from another place on the scope. Easy to do and mates well with CGEM. Now to polar align and collimate....






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