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Binoviewers and Night vision devices

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#1 Jethro7

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Posted 04 July 2020 - 09:32 AM

Hello CN's

Has anyone used a nightvision device with a binoviewer?

 

HAPPY SKIES AND KEEP LOOKING UP Jethro



#2 alphatripleplus

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Posted 04 July 2020 - 10:44 AM

Moving this over to the new Night Vision Forum from EAA.



#3 TOMDEY

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Posted 04 July 2020 - 11:07 AM

Yes --- with two Night vision "eyepieces" in the receiving end of the light.

 

The difficulty is getting it to focus and the acceptance-speed (input F#) of the BV itself. I use this one, which comprises a zero-shift optical configuation, and overcomes both of those problems. It works fine, with an F/6 feed. I haven't tried faster than that.    Tom

Attached Thumbnails

  • 12 Orion Linear binoviewer.jpg
  • 11 binoviewer inside 150.jpg

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#4 Eddgie

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Posted 04 July 2020 - 11:17 AM

Hello CN's

Has anyone used a nightvision device with a binoviewer?

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Yes.   It is not something I recommend though using the BV that TOMDEY shows is probably the best way to do it.

 

 

 

There two major reasons.  The first is that the beam splitter means that each eyepiece only gets about 50% illumination (disregarding transmission losses).   Because image intensifiers do best when the focal ratio is faster, cutting the light in half is like doubling the focal ratio.

 

The second is that with the long light path in the binoviewer, unless the scope is reasonably slow the fully illuminated circle can get very small (we are talking just a few millimeters, depending on the speed of the scope) and this further dims the image. Now for a small Globular at the center of the field this might not matter, but for nebula that would extend well out from the center of the field, the vignetting will be prominent.

Now there is one other reason and that is unless the scope can reach focus without a Barlow or GPC and when you do that, once again, it is like using a slower focal ratio.

 

I have done it and I don't recommend it.  it works, but not all that well for most things.

 

If you want to use two eyes, it is better to use a PVS-7 than use a binoviewer with two monoculars as eyepieces.  The PVS-7 reaches focus in almost all telescopes, including Dobs, with no need for any kind of amplifier.  It does not have the beam splitter penalty of the standard Binoviewer. You can often find a nice, used Gen 3 PVS-7 for sale for less than the cost of a big prism binoviewer, special diagonals, and expensive eyepieces.

 

 

PVS 7 in dob.jpg


Edited by Eddgie, 04 July 2020 - 11:18 AM.

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#5 Jethro7

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Posted 04 July 2020 - 11:39 AM

Yes.   It is not something I recommend though using the BV that TOMDEY shows is probably the best way to do 

Thank you TOMDEY, and Eddgie,

I was just having a odd  thought early this morning. What you say makes sense. The whole game of nightvision is Photons. At least now I know how to do it. I think however I would have a hard time buying PVS 7's, I hated these things when I was issuesd them. The PVS 14's rocked. I wished I had the ones I own now when I was in service.

 

HAPPY FOURTH OF JULY, AND KEEP LOOKING UP Jethro



#6 highfnum

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Posted 08 July 2020 - 01:45 PM

there is alternate

panoramic lens

its Bi-Ocular

one lens but 2 eyes

 

no splitting 

Biph used this approach

 

interesting fact - it has a huge eye relief 

you can be 3 feet away and still see image 

kinda perfect for covid-19 world

biphscreen.jpg

 

 



#7 joelin

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Posted 08 July 2020 - 03:30 PM

there is alternate

panoramic lens

its Bi-Ocular

one lens but 2 eyes

 

no splitting 

Biph used this approach

 

interesting fact - it has a huge eye relief 

you can be 3 feet away and still see image 

kinda perfect for covid-19 world

attachicon.gifbiphscreen.jpg

interesting, whats the name of this product and where can i find more about it?



#8 highfnum

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Posted 08 July 2020 - 03:50 PM

not making anymore 

 

just service of ones already made

http://nightvisionastronomy.com/



#9 The Ardent

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Posted 08 July 2020 - 04:12 PM

There was a nice article about BIPH in Amateur Astronomy Magazine a few years ago.


interesting, whats the name of this product and where can i find more about it?




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