How to make your own lens scope converter for ~ $35

Discussion in 'Nikon' started by darren_cokin, Aug 15, 2006.

  1. This post is long overdue. I typed up notes after I completed the project 6 months ago, but never got around to taking the pictures. Just this week I bought a 2nd speedlight and some umbrellas, so I decided to make it a lesson in product photography. (Look ma, no shadows!)

    This is a follow up to an old thread I started when I was first researching this project:

    If you don't know what a Lens Scope Converter is, and why it's useful, read this:

    (Surprisingly, my initial post is now google ranked above that. The Ken Rockwell's article used to be #1.)

    Nikon's version is no longer made, and I became very frustrated trying to buy one last year. Ebay prices went up to $500. I just checked the site now, and see that one lucky buyer did get one for $86 two weeks ago, but several others sold for over $300. That's too much.

    The one I built cost me about $35, and is actually better than Nikon's original, because it supports G lenses that don't have an aperture ring. (Though it would probably be easy to modify Nikon's version for G's... keep reading.)

    Here's what mine looks like:
  2. Here's it attached to an 18-200mm lens. This becomes a 1.8x - 20x magnification scope. The magnification is equal to the focal length of the lens, divided by the focal length of the eyepiece, 10mm is this case. With my 80-400mm zoom, I've got a 40x scope, which I use often to gaze at the moon.
  3. What you need:

    Basically, this is pretty simple. Take a telescope eyepiece, and affix it to a rear lens cap. However, if you use a normal telescope eyepiece, you'll wind up with an inverted image. To get an erect image, you need to use an inverting eyepiece. Surprisingly, there seems to be only one such animal on the market! It's made by Skywatcher Telescope. Their info page is here:

    Unfortunately for many of us, they don't seem to have any dealers in the USA. Several Canadian dealers have it though. I got mine here:

    (After a debacle. I initially ordered one from, but they sent me something else. Apparantly they never even stocked it, and had mistakenly pasted it's description on their catalog page for another part.)

    European customers have many choices: option 1, option 2, option 3, option 4

    It comes in a kit with a plastic extension tube, which you could cut down and glue directly to a rear lens cap you've cut a big hole in.
  4. I wanted to save my extension tube though, (for potential use in phase II of this project - see my next thread), so I fabricated my own attachment using a piece of a plumbing fitting I bought at Home Depot for $1. A pipe band clamp locks it in place. Here's a view of it disassembled. Notice in the pictures above, I put some black electrical tape around the band clamp, mainly for aesthetics.
  5. If you don't care about G lens compatibility, use any old rear lens cap. If you do care about G lens compatibility, I recommend you use one that came with a Sigma brand lens.

    When I started buying Sigma lenses, their rear caps really annoyed me. I was always fumbling to get them on. Whereas Nikon caps can slip on in any of 3 orientations, the Sigma only goes on one way, and the alignment dot is hard to see. For this reason, I had replaced all my Sigma caps with Nikon caps before I began this project, and had a few lying around. (Individually, Nikon caps are expensive, but I found a cheap 5 pack on Ebay.) Only going on one way is important, so the little doohickey you're going to attach will always be aligned with the aperture lever.

    With a G lens, you don't have an aperture ring to open up, so in order to let in the light, something has to be pushing open the aperture level that connects to the camera. Fortunately, it needs to be pushed in the same direction you twist the cap, so a simple 'stop' inside the cap will do the trick. It takes a bit of care to measure and place it in just the right spot. Since I knew I couldn't align it perfectly, and didn't want to risk bending the aperture lever by twisting the cap too far, I chose to make the little doohickey out of some high density foam I had lying around, instead of rigid plastic. The foam will give before the aperture lever does. This stuff had a self adhesive back, and was easy to cut, so it was convenient to use as well. (I think it came from an electronics shop, but I'm not sure. An old roommate left me with a few blocks of it.) If you can't find something like that, maybe cut off a bit of a kitchen sponge, and glue it in place. (Self adhesive weatherstripping foam may be a bit to pliable to actually push the lever, it has to be high density foam.)
  6. To get it focused, I first mounted my longest lens (the one with a collar) on a tripod, and autofocused on a distant subject. Then I removed the camera, and put my converter on the back of the lens, with the band clamp still loose. I adjusted the position of the eyepiece back and forth until it was focused, and tightened the band clamp.


    If you make one, drop me a line!

    And if you want to help with "phase II", adding a battery and circuit board to fire up the Vibration Reduction, please reply to my next thread...

  7. Thank you Darren, I very much appreciate your effort and might try myself your project. Marco
  8. Thanks for the post. I've wanted a lens scope converter for some time.


    Dave Hartman.
  9. An excellent DIY idea. Thanks for sharing.
  10. Darren, How about the Pronea S? Check if it is compatible with VR stuff.
  11. What a great idea Darren!

    Interesting tidbit on the Nikon lens Scope converter in 1988:

    Wholesale for 1-2 $36.25

    Wholesale for 3-5 $35.16

    Wholesale 6 or more $34.44

    MSRP $72.50

    I posted these nikon 1988 dealer prices as (for~me) it shows how inexpensive this item was to manufacture. You solution is brilliant and can constructed for all 35mm lens mounts.

    Thanks for sharing!

  12. I paid $160 for one last year from KEH. It was worth it!
  13. Hi, I've been looking for this info, I have tested a 40mm eyepiece of a crystalvue monocular and it works well with my Canon 100-400 lens but the image is mirrored. I am going to order the erecting eyepiece.
    About the image stabilization, one could simply attach the pins on the camera body to the pins on the lens with a cable.
    You seem to be a handy person, how would you make a cable for that?
  14. I have tried to make one for a Canon EF 100-400 , with a erecting diagonal 45� and an eyepiece 10mm. It only works for close up (macro range till about 5m - focusing allways to about 10m to Inf.) and the DOF is very narrow. I even tried different extension tube lengths. I also tried with a crystalvue eyepiece and the results are pretty the same. I wonder what is wrong ? I guess either the lens when switched off becomes a closeup lens or the eyepice (mm) is too small (too big maginification for this assembly to work) ...
    With other Canon lens (50mm 1.8 and 17-85) the same happens: short working distances... Agaian, I wonder if any setup would work to turn canon lens into a scope ?
  15. Joaquim,
    Any brand of lens should work, doesn't matter. The problem is the 45 degree erecting diagonal, and/or the extension tubes you're trying to use. There isn't enough room in the light path for those. Read Joseph Wisniewski's response to my first thread on this subject (follow link given in first post above); he explains the registration distance problem. Also have a look at the first picture I posted above, and notice how close the back of the eyepiece is to the ring where the lens is mounted. There's just a few millimeters between the back of the lens and the front of the eyepiece.

    If you get rid of the diagonal, and hold the eyepiece right up to the back of the lens, so close that they are nearly touching, then you should be able to focus on anything. But, your image will be inverted, unless you get that special eyepiece I described that has the erecting feature built in. That's why that eyepiece was such a find, and warranted me putting up this article in the first place. It seems to be the only one that will work to give you an upright image with a camera lens.

    Good luck.

  16. bookmark
  17. Thanks Darren, it works with the eyepiece alone, at all working distances and on every lens I have. I see I need an eyepiece that erects the image..
    (with the diagonal it does not work because it adds too much extension to it)
  18. Darren, I was able to order that erecting eyepiece from a site on the UK , It works very well on the canon EF 100-400 and even on the 50mm F1.8.
    EF lens do not have a closed diafragm (as nikons do) - it's even easier to make an adapter for EF's. The DOF at 400mm is narrow but usable.
    Thank you.
  19. The last post was a while ago but the tread is still useful today! Thanks for that.
    I built myself one of those last week and used it last night with an old 300mm f/2.8 AI-S lens for an astronomy night. I heard many "wows" when people looked through it. They even mentioned that they preferred the view from my set up then from the gigantic telescopes some people had around. Check it out:
    <a href="" title=""><img src="" title="" alt=""></a>
  20. Thanks for posting Guillaume, I'm delighted people are still finding this.
  21. No problem, I've been wanting to make one of those for a while and I finally got discouraged by the very high price of the Nikon genuine one. It was a fun little project with my uncle who insisted on making the whole thing in his lathe of course... So the fit is super precise and I just used some Gorilla Glue to bound the tube and the cap together. I figured that if it breaks, I'll just use the really good stuff. So far it's solid, besides creating some white residue everywhere, the Gorilla Glue seems to be working great.
    Did you ever get around to making the VR compatible version?
    Sorry for the annoying links, I was trying to embed a picture of the set-up but it didn't turn out so well. The link still works though: [​IMG]
  22. "Did you ever get around to making the VR compatible version?"

    No, sorry, other interests have taken priority. Know any EE students looking for a project?

Share This Page