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lens2scope alternative? (mount diagonal/EP on a telephoto lens)

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#1 nicolachel

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Posted 25 April 2018 - 04:14 AM

Just wondering is there an alternative to the lens2scope thing that would allow one to mount a standard 1.25 " or 2" diagonal/EP to a telephoto lens (Like F mount) to turn it into a refractor?

 

As I understand lens2scope has a built in 10mm EP and thus doesn't allow the use of others.


Edited by nicolachel, 25 April 2018 - 04:15 AM.


#2 Mark9473

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Posted 25 April 2018 - 06:41 AM

I like this approach: a diagonal body (nosepiece removed) glued to a rear lens cap with a opening cut into it.

http://www.bobatkins...pe-adapter.html

 

Forget about the 2" option; the lens won't have enough back focus. Nikon F mount has only something like 46 mm to work with.



#3 Mark9473

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Posted 25 April 2018 - 06:46 AM

Here's one with a parts list: http://www.nobell.or...fspottingscope/



#4 nicolachel

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Posted 25 April 2018 - 10:10 PM

Thanks Mark! Thanks like an interesting DIY projectlol.gif



#5 luxo II

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Posted 26 April 2018 - 05:27 AM

Made one once for PK telephoto lenses by cannibalising a slim 5mm metal extension ring to use for the bayonet mount - far stronger than a lens cap and also locks in place so no risk of it falling off in the dark.

Using a jewellers screwdriver, removed the bayonet on the rear of the extension ring and the aperture mechanism then glued a 1.25” eyepiece adapter on the back using araldite - this lasted perfectly for many years.

There’s really no room for star diagonals of any sort - though I did try 1.25” a prism diagonal.

Lenses used were a 135mm f/2.8 - that really had to be stopped down to f/4, so it was really only about 30mm real aperture - and a 500mm f/8 mirror lens which made quite a nice super finder.

Eyepieces that worked well included an old Meade 20mm Erfle and LV 25mm. From memory the RKE 28 and 21 were not able to achieve sharp focus over the full field of view.

Edited by luxo II, 26 April 2018 - 05:35 AM.


#6 TONGKW

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Posted 26 April 2018 - 07:47 AM

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I have built a spotting scope with a old 400 mm f/5.6 telephoto lens, using a Nikon to 1.25” adapter, the front lens from a Celestron 2x Barlow and a 1.25” correct image diagonal.
All my 1.25” eyepiece will come to infinity focus and the image is sharp up to 80x which is good enough for birdwatching.

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Spotting Sun-001.jpg

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#7 TONGKW

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Posted 26 April 2018 - 07:55 AM

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The adapter has fittings for Nikon, Canon and Sony lens and was obtained from this website:-

https://item.taobao....&id=14902366113

I don’t know whether this adapter is obtainable in the US.
The cost of the adapter is RMB166= US$30 approximately plus postage.

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Attached Thumbnails

  • GRUS 相機鏡  1.25吋接口.jpg
  • GRUS 1.25-inch adapter.jpg
  • GRUS 1.25-inch adapter.jpg
  • GRUS 1.25-inch adapter.jpg
  • GRUS 1.25-inch adapter.jpg
  • GRUS 1.25-inch adapter.jpg

Edited by TONGKW, 26 April 2018 - 07:57 AM.


#8 TONGKW

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Posted 26 April 2018 - 08:02 AM

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I am sorry that the image of the adapter has been posted too many times. 

But it appears that I am not able to  delete the surplus images.

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