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Spacing of the OCS and magnification?

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#1 De Lorme

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Posted 14 November 2019 - 06:06 PM

Hello,

 

Thanks for the great help.  I have a WO 2x ocs and a Arcturus 3x ocs, what would be the magnification if I screwed a pair{either}into my Meade zoom eyepieces

and then inserted the zooms into my Baader/Celestron binoviewers?  When I bought the Baader 2" T2 nosepiece it opened up the view is the first reason I don't want to screw the OCS directly into the nose of the binoviewer. The second is that it makes the optical train really long which puts a lot of strain on the focuser. And third I'm trying to shorten the height of the eyepiece{when inserted into the Tv 3x barlows}.

 

FYI right now I'm able to come to focus without my 3x Tv barlow{I rack the focuser out about 11mm}and I can still come to focus with the TV barlows{inserted into the binos} racked out to about 35mm. The focuser draw tube is 45mm. 

 

Thanks for answering my questions,

 

De Lorme



#2 Eddgie

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Posted 14 November 2019 - 07:05 PM

First, if you already have everything, then why not just to try it out?

 

These are more or less Barlow lenses and like any Barlow, the magnification will increase with separation from the focal plane and decrease as you move them closer to the focal plane.

 

I am not positive that I understand what you want to do but a Barlow that was designed to give 2x with 96mm of spacing would probably give only 1.2x or something if you used it in the eyepiece.  So, if you were using a 3x, then the total magnification would be 3.2x maybe? I am having a lot of difficulty with exactly where you are trying to go.

 

I guess I am not sure that I understand what you are trying to do though.  I mean I know you want to use the Barlows on the eyepieces, but I don't understand the goal, but I guess that is not important. Used the way you describe, (screwed into eyepieces) the power will only be maybe 1.2x.


Edited by Eddgie, 14 November 2019 - 07:06 PM.


#3 De Lorme

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Posted 14 November 2019 - 09:20 PM

Hi Eddgie,

 

I only have one of each of the WO 2x and Arcturus 3x ocs.   The goal is shorten the eyepiece height. Instead of using the Tv 3x balorw{for the moon and planets only}I would rather use the one of the two ocs above which would give the best magnification range when screwed into the Meade zoom eyepieces.  I can't use just the 1.25" ocs's because the nosepiece isn't threaded for it. I can make it work{to come to focus} by using adapters and extension tubes but the length now puts a lot of strain on the focuser plus the 1.25" nosepiece restricts the  field of view.. The Baader 2" T2 opened up the FOV and to not loose the FOV I gained I use the TV 3x barlow inserted into the binos.  With the barlows in I only have to rack the focuser out about 11mm without the barlows I have rack the focuser out about 35mm. Draw tube is 45mm,so within reason to make it work.

 

  Just didn't realize this was an option until I was informed  by another user of these binos that he was able to get to 270x with his 5" f8{1040} apo by using a pair 1.6x WO ocs's screwed into a pair of 6mm orthos.  If he was using  barlows I think he would be correct about the magnification but not when using the 1.6x ocs.

 

Do I make sense now? LOL

 

Clear Skies,  De Lorme



#4 Eddgie

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Posted 14 November 2019 - 10:10 PM

I am sorry, I guess I just don't understand, but to answer your question, the 2x OCS lens screwed directly to the eyepiece is probably only going to give maybe 1.2x.

 

If you need more power than this, consider just buying a pair of cheap shorty Barlows and use the elements in these.   If I understand what you are trying to do, then you could just unscrew the Barlow cells and screw them into the eyepieces, and these will be shorter than the binoviewer OCSs and give more power.

 

But I need to stop trying to help because I am not really sure if I understand what you are trying to do.




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