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Mounting an Old Refractor

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#26 MAT_Blue

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Posted 13 February 2019 - 05:16 PM

Buy a 2” GSO single speed focuser from Agena for about $150, take out the three screws, remove the existing focuser, install the 2” and secure with the three screws ! It fits perfectly, took me about 20 minutes ! If you need some info Agena is great to supply their knowledge ! Just make sure you have the ID of the tube to match the proper size focuser !

Looking at the pix of your scope, it doesn't look like you had to add an extender to get focus with the 2" focuser.  The Agena web site says one may be needed.  Not??



#27 LDW47

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Posted 13 February 2019 - 06:19 PM

Looking at the pix of your scope, it doesn't look like you had to add an extender to get focus with the 2" focuser.  The Agena web site says one may be needed.  Not??

Agena says that just to cover their rear in those times with some scopes where you do need one, all companys cover their a*s ! They don’t know what scope each person who orders a rplacement focuser has unless you contact / talk to them, which you can do, then you will get the low down on a particular scope ! I will say I sure didn’t need one with my C80 !


Edited by LDW47, 13 February 2019 - 06:24 PM.

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#28 MAT_Blue

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Posted 13 February 2019 - 07:37 PM

Agena says that just to cover their rear in those times with some scopes where you do need one, all companys cover their a*s ! They don’t know what scope each person who orders a rplacement focuser has unless you contact / talk to them, which you can do, then you will get the low down on a particular scope ! I will say I sure didn’t need one with my C80 !

Thanks.  The stock focuser will extend out to 230mm from the end of the tube.  The GSO one will only go about 175mm (per the specs on the Agena web site).  I don't think I ever got the focuser extended that far out.

If you get a chance, could you take a couple of close-in pix of the focuser installation on your scope and post them?  Thanks in advance.



#29 LDW47

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Posted 13 February 2019 - 09:02 PM

DCFF31BE-81E3-4E71-BDA1-39421B875625.jpeg

Thanks.  The stock focuser will extend out to 230mm from the end of the tube.  The GSO one will only go about 175mm (per the specs on the Agena web site).  I don't think I ever got the focuser extended that far out.

If you get a chance, could you take a couple of close-in pix of the focuser installation on your scope and post them?  Thanks in advance.

Here are the pics you requested, I really don’t know what you are looking for / to see ? I hope these will do !

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#30 MAT_Blue

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Posted 13 February 2019 - 09:26 PM

attachicon.gif DCFF31BE-81E3-4E71-BDA1-39421B875625.jpeg

Here are the pics you requested, I really don’t know what you are looking for / to see ? I hope these will do !

 

Thanks a lot.  Those are perfect   I just wanted to see what it looked like installed.   Looks very simple.  I feel really confident it will work great.  I ordered mine today.  Can't wait now.


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#31 LDW47

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Posted 13 February 2019 - 09:33 PM

Thanks a lot.  Those are perfect   I just wanted to see what it looked like installed.   Looks very simple.  I feel really confident it will work great.  I ordered mine today.  Can't wait now.

It will, they are a great focuser for the price as you can see !



#32 MAT_Blue

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Posted 21 February 2019 - 05:02 PM

This is an excellent scope for its optics, and you will like the sharp views of doubles, etc. 

 

You have several choice for setting up a dovetail.

 

The first is similar to the note above by Starman876, except you will see that one of the rings does not clamp down to the OTA tube.. it was desinged to be held in place by the Vixen Celestron Alt-az mount itself, which slotted into those small rectangular areas on the rings that you measured.  You would drill into those slots to attach the dovetail, but would stilll have the problem that one ring has no clamping option. You also face the problem that that only way to get the rings off of the OTA, is to remove the dewshield or focuser and slide them off. 

 

A logistically easier solution (but more $$) is to buy a  set of hinged rings and attach the dovetail to them.

 

Great scope and worth the effort to find the best mounting options for you.

 

Mike

I ended up getting the hinged rings from Agena.  Work great.  Thanks for the tip.



#33 Brent Campbell

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Posted 24 February 2019 - 10:11 AM

The original alt atz mounts do suck.  I purchased a vixen Polaris mount head and transfered the alt atz mounts legs to it.  The original rings with Scope seem to fit well.   Sadly I’m going to be selling this Scope soon because it’s redundant to my Astro tech 102 Ed which has a similar focal length.



#34 MAT_Blue

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Posted 24 February 2019 - 04:26 PM

The original alt atz mounts do suck.  I purchased a vixen Polaris mount head and transfered the alt atz mounts legs to it.  The original rings with Scope seem to fit well.   Sadly I’m going to be selling this Scope soon because it’s redundant to my Astro tech 102 Ed which has a similar focal length.

Hope the old Firstscope finds a good home.



#35 photoracer18

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Posted 06 March 2019 - 05:39 PM

BTW, do you remember what dovetail bar and rings you used?  I bought an 11 inch dovetail bar from Agena and was going to see if I could do something with the existing rings.  I have a set of rings on my wishlist at Agena in case I need them.  They are:
https://agenaastro.c...e-ring-3-5.html
I measured the OD of the scope at 3 9/16", which is close enough, I suppose, for these rings advertised as 3.47 to 3.54 inches.
 
The main reason I wanted to keep the CB-80 was to use it as a short-focus scope for use with an ASI224MC camera.  I figure with a 0.5 focal reducer, I should be able to capture all of M31 and similar sized objects with it.  Something I don't think I could do with my 1500mm focal length NexStar 6SE.  I'm figuring the focal reducer will turn it from 910mm to 455mm focal length.


The chance is good that the 80mm will not be able to reach focus with a .5x focal reducer. Most of those type of reducers were made for SCTs which have a much larger range of focus than a refractor. Most if not all refractor reducers fall in the .7x range for the reasons I mentioned. Plus while you can use SCT reducers on refractors that have similar F-ratios you can't go as short as an SCT.

#36 LDW47

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Posted 16 March 2019 - 09:12 AM

Did you ever get / install a 2” GSO focuser for your scope ?


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#37 MAT_Blue

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Posted 16 March 2019 - 06:09 PM

Did you ever get / install a 2” GSO focuser for your scope ?

No.  Not yet.  The weather here (St. Louis, MO) has been awful and I've got lots of other stuff to do.  Thanks for staying in touch, though.  If I get around to it anytime soon, I'll be sure to post something here to let people know how it went.

I did get the scope rings and mounted the Vixen bar and had one night with it using the goto alt-az mount that came with my NexStar 6SE.  Worked reasonably well.  It wasn't a "wow what a great scope" experience.  But the seeing was not good and it's pretty light-polluted where I live.  I haven't had a chance to use it in decent weather, good seeing and dark skies yet.


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#38 pdxmoon

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Posted 17 March 2019 - 10:52 PM

Mount away! I have dove bars on all my classics (Tasco, Unitron) and mount on modern mounts like Porta II all the time. Great way to re-use these old beauties! Good luck!


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