DIY Hexar RF Eyepiece

Regular readers will recall that I recently lost the eyepiece for one of my Hexar RF bodies. After a couple of days unsuccessfully trolling the usual internet outlets for weird camera junk, I decided to build my own replacement eyepiece. Unlike a lot of cameras, the standard rear eyepiece of the Hexar RF is not just a clear piece of glass, it’s the last element in a reverse telescope (Note to camera designers: crucial bits should not come susceptible to random unscrewing!). Unfortunately, the diopters for the Hexar seem to work in tandem with the eyepiece, so the -3 and -4 diopters I got from KEH were pretty much useless. Using the eyepiece off my other body and a formula my dad gave me, I figured out that the eyepiece has a focal length of just about 52mm.


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A little poking around on the internet located the good folks at http://www.surplusshed.com/. I highly recommend them over Edmund Optics. For one thing, they are significantly cheaper – like $4 for a lens instead of $20. For another, they have a convenient lens finder that locates your lens based on focal length and diameter. A quick search for 50mm-ish lenses around 15mm in diameter located a number of potential candidates. At $4 each I figured better safe than sorry, so I ordered a couple of extras on either side of 50mm. When my order arrived a few days later, it turned out that the 51mm was just about perfect. Next came the task of mounting it on the camera.

Once again I called on the ingenuity of my father (one of the benefits of temporarily living at home). After tossing a few ideas back and forth, he disappeared into the garage. Thirty minutes later he presented me with this:


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A strip of copper sheeting was soldered into a cylinder sized to fit over the original screw threads on the body. One end was clipped and bent down to a narrow diameter in order to hold the lens in place. The lens was positioned on top of the threads. The copper cylinder was glued down to hold the whole works in place. Although dad was in favor of painting the copper, I’m thinking about leaving it shiny. Who else has a copper and black Hexar RF?

So, how does it work? Dandy. Comparing the repaired Hexar with my other one, it’s pretty clear that focusing accuracy and viewfinder brightness are undiminished. Eye relief remains the same as well. The replacement lens is not quite as flat as the original equipment. This increased curvature results in a slightly different focal length outside the center portion of the lens requiring dead center eyeball position to hold the whole field in focus. Having used it like this for a few days, I don’t notice the difference when actually photographing. I’ve always been pretty careful about centering my eye, so perhaps other users would have more of a problem with this

I’m quite pleased with this repair. It’s piqued my curiosity about the possibility of building a VF magnifier for the Hexar. A .9 VF would give me a reason to go buy that Noctilux I’ve always wanted.

Update 12/26/06: The copper sleave that I was using to hold the lens on ended up scratching my glasses. Since a couple of months of use demonstrated that the lens indeed worked, I decided to super-glue it on as a more permanent solution. A couple of drops of glue around the edge of lens seems to be holding it in place just fine.

8 thoughts on “DIY Hexar RF Eyepiece

  1. Matt,

    Does 51mm fit just inside the tube, or on top of it? I wonder if an empty diopter ring from another camera might be used to hold it in place.

    Bill

  2. 15 sits on top. I think inside is something like 12mm. I worried about securing a lens actually inside the threaded tube, but you could probably rig something.

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