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focal reducer on cheap binoviewer

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#1 preprius

preprius

    Mariner 2

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Posted 17 January 2024 - 08:20 PM

I wanted to share an experiment with the bino group.

 

I found this on Orion Telescopes. . 

https://www.telescop...keyword=reducer

 

It also screws into the bottom eyepieces and the binoviewer, just like a filter.

 

My problem:

Binoviewers don't quite get focus on my EON80MM refractor without the little doubler.  They do get focus when using the little doubler that screws into the bottom of the bino but the focuser reaches max in focus. Really close to focus but a bit more would be better.

 

So experiment was to use the focal reducer on binoviewer to see if it can get focus in my EON80mm.

Steps:

1)  get binoviewer to focus point using doubler.  

2)  remove doubler and put reducer in.    (FAIL).  See nothin

3)  put doubler over the reducer               (FAIL).  See shadows

4)  swap doubler and reducer positions   (FAIL).   See shadows maybe a bit better.

 

move to single eyepiece:

reducer works on the eyepieces just fine.  

 

try eyepiece with reducer in binoviewers.   (FAIL). 

      -eyepiece does not lay on top of the eyepiece holders,  it bottoms out on fixed metal shelf.

 

Well now I have a 0.5 reducer for 1.25 inch eyepieces.  

 

$40 dollar experiment FAILED.

 

I went down the path of Siebert solutions.  But I decided the binoviewer was not that important on EON80mm. The binoviewer works really good on CPC1100.

 

Me. Mark Eason

 

 

 



#2 shohin

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Posted 17 January 2024 - 08:49 PM

So with the doubler (this is a Barlow?) you're fully racked in and still not focusing? One more experiment for you. Take the glass out of the reducer (remember the orientation so you can reassemble later) so it's just an extension tube. Put the extension tube between the BV and the doubler. The doubler should then become a doubler+, pushing the focus point out further.



#3 preprius

preprius

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Posted 17 January 2024 - 09:01 PM

So with the doubler (this is a Barlow?) you're fully racked in and still not focusing? One more experiment for you. Take the glass out of the reducer (remember the orientation so you can reassemble later) so it's just an extension tube. Put the extension tube between the BV and the doubler. The doubler should then become a doubler+, pushing the focus point out further.

Oh I like experiments. . . 

I will check it out. 

The intent is to get no Barlow (doubler) to work with BV.

 

But getting BV to work is also good. 

 

Thanks.



#4 RichA

RichA

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Posted 17 January 2024 - 09:14 PM

Oh I like experiments. . . 

I will check it out. 

The intent is to get no Barlow (doubler) to work with BV.

 

But getting BV to work is also good. 

 

Thanks.

There's nothing you can do with a compressor (reducer) that will bring the focal point out, it'll drag it in.  Binoviewers can require many inches of in-travel because the light-path through the binoviewer can be six inches or more.  This why a barlow is most often needed in the insertion tube, to bring out the focal point so it can accommodate the binoviewer's light path length.  Maks and SCTs are more adaptable to these things than most refractors, especially today that refractor focusers only have about 3-4 inches of travel.


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