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Tight Diagonal...

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#1 Dave Bush

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Posted 12 June 2019 - 10:08 PM

I've got GSO 2" Quartz SCT-style diagonal that is just a bit too tight for my eyepieces (Ethos all).

 

I can get them in but it take some jostling.

 

I'm curious if anyone else has had one of these that behaved similarly and if so, did you find another model that was better?



#2 jeremiah2229

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Posted 13 June 2019 - 12:19 AM

It might be the brass compression ring. I've seen some there were quite thin and deformed easily so give this a good look over. Maybe best to remove it and inspect but you can also tell if badly out of shape by just looking while still in.

 

 

Peace...


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#3 Dave Bush

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Posted 13 June 2019 - 08:47 AM

It might be the brass compression ring. I've seen some there were quite thin and deformed easily so give this a good look over. Maybe best to remove it and inspect but you can also tell if badly out of shape by just looking while still in.

 

 

Peace...

No, I removed the brass ring and use only nylon screws.   The eyepieces are hanging up on the housing itself.



#4 Starman1

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Posted 13 June 2019 - 01:05 PM

Plus and minus tolerances.  A second GSO diagonal might not have the same issue.


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#5 csrlice12

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Posted 13 June 2019 - 02:35 PM

Lightly sand the upper compression ring slot (cover the mirror)?  Removing the 90* edge might allow easier removal.  I also support the diagonal with my other hand when removing heavy eyepieces, especially if the focuser is racked out, with an SCT that might not apply.



#6 Dave Bush

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Posted 13 June 2019 - 03:11 PM

Plus and minus tolerances.  A second GSO diagonal might not have the same issue.

Indeed that was it.  I happened to have an older model of the same GSO diagonal and my eyepieces slide right in.  So I swapped the eyepiece portions.

 

Thanks Don


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#7 Mike W

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Posted 13 June 2019 - 03:36 PM

I've got GSO 2" Quartz SCT-style diagonal that is just a bit too tight for my eyepieces (Ethos all).

 

I can get them in but it take some jostling.

 

I'm curious if anyone else has had one of these that behaved similarly and if so, did you find another model that was better?

Televue is better!tongue2.gif 



#8 Dave Bush

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Posted 13 June 2019 - 04:02 PM

Televue is better!tongue2.gif

Do they make an SCT style now?



#9 Starman1

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Posted 13 June 2019 - 04:08 PM

Do they make an SCT style now?

No, but they have a lot larger clear aperture all the way through than most 2" diagonals.


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#10 vahe

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Posted 13 June 2019 - 04:08 PM

Televue is better!tongue2.gif

I have a TV 2" mirror diagonal, it is at least 20 years old, its barrel is just a little too fat to slide into my TEC6, all my other 2" accessories including Zeiss binoviewer work fine with the Mak but the TV diagonal would not fit no matter how much pressure is applied.

.

Vahe



#11 Dave Bush

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Posted 13 June 2019 - 04:34 PM

No, but they have a lot larger clear aperture all the way through than most 2" diagonals.

The GSO models I have appear to be the full 2" barrel on both ends.  Just an ever so slight stop for the eyepiece.



#12 Starman1

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Posted 13 June 2019 - 07:51 PM

It is not an SCT version, then.
Those have significant stops in them.

#13 junomike

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Posted 14 June 2019 - 08:50 AM

Aside from the premium Diagonals (AP/TV) I only found two that had a full 2" opening at each end.  The GSO and the WO Dura-Brite.

All were of course Refractor (nose) Diagonals.



#14 Dave Bush

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Posted 14 June 2019 - 08:58 AM

It is not an SCT version, then.
Those have significant stops in them.

This is an SCT version.  It screws right onto the back of the scope.  

 

But, I believe I know what you're talking about.  The nose piece does appear to be less than 2".    I'll have to find my calipers and measure mine when I get home.


Edited by Dave Bush, 14 June 2019 - 09:01 AM.


#15 Starman1

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Posted 14 June 2019 - 09:36 AM

This is an SCT version.  It screws right onto the back of the scope.  

 

But, I believe I know what you're talking about.  The nose piece does appear to be less than 2".    I'll have to find my calipers and measure mine when I get home.

The smaller opening of the SCT type won't make a difference in an 8" SCT (or smaller), but it could in a larger SCT, where it is even desirable to

replace the 3-1/4" rear plate with a type having a full 2" opening.




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