Contax 137MA Mirror Support

I posted about this in the Contax / Yashica group, but wanted to broaden its coverage.

I have a couple of Contax 137 MA cameras that are missing the plastic nub that goes onto the mirror support within the body of the camera. The mirror sits on this when in the down position. Without this, the mirror isn't positioned properly, resulting in focus misalignment issues (i.e., unless shooting at infinity, the focal plane will lie behind the intended subject, which appears in focus through the eyepiece, but every subject will be out of focus in the actual photo).

These nubs/cushions, which look like little O-rings, are made of plastic, and become brittle over time. I've purchased old/inoperative 137's to cannibalize, but even this hasn't been all that successful as they are either missing the part, or it breaks upon removal and/or placement in the working camera body. I've tried going to the local hardware store and purchasing the smallest rubber O-ring they have on hand, and yet these are too large.

Does anyone here know of a workaround and/or a source for these little parts? Without them, the camera is bricked. (And I won't comment on how poor of a design flaw this is.)

I'm also curious on this and posting to keep the thread alive.....

I won't say with certainty that this is possible, because I don't know the precision with which 3D printers can work (can they make something the size you need or will they require too large of a plastic bead to extrude?), but if they can, this is a perfect application for 3D printing.

Looking into whether 3D printing would work is interesting, but something I've never done before nor know how to do.

Are you sure the mirror hasn't slid down? I have two Contax 137MA cameras. The second one didn't focus properly (and also the mirror would get stuck against the back end of some lenses). After moving the mirror back up, it works very well. There's nothing on the peg that supports the mirror.


Test shot with a Kiron 28-105mm lens.

I can't fully imagine what the part looks like but how about making rubber O rings from the outer insulation of electrical cable? If it needs to be bouncy use some silicone cable outer.

Duceman said:

Looking into whether 3D printing would work is interesting, but something I've never done before nor know how to do.

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I've not done it myself, but I have a vague understanding of the basic principles. Since this would be a very small job, both literally and figuratively, it would be relatively expensive per unit, but you could farm the actual production out to someone like Shapeways, who even offer design services so you wouldn't have to learn CAD software. That's probably going to make your two little o-rings rather expensive, if that's all you wanted to make, but it could be done.

Well, I can report now that it appears the 137MD has a different type of nub as compared to the MA. Bought a parts MD off the Bay to see if I could use the nub (hoping it would have one when it arrived). The nub is there, but I can't get that sucker off! Doesn't simply pop off like the others I've tried with the MA (and the 139 as well--but that's a different size nub). Unless the one I have is just sticky, but I'm afraid I'm going to break it if I try much harder.

TheFlyingCamera said:

I've not done it myself, but I have a vague understanding of the basic principles. Since this would be a very small job, both literally and figuratively, it would be relatively expensive per unit, but you could farm the actual production out to someone like Shapeways, who even offer design services so you wouldn't have to learn CAD software. That's probably going to make your two little o-rings rather expensive, if that's all you wanted to make, but it could be done.

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If it's a common fault on these cameras and someone's having some made , they could just as easily have a batch made and start selling them on , here or on eBay etc
Apart from fixing up their own camera and helping others to do the same , they'll be able to make some money out of it instead of it costing them money .

I have, to date, only designed and 3-D printed one thing (a battery holder for a Bronica). My two cents are that the strength of the process is that you can make fairly complex objects that previously would have to be injection molded. I don't think that precision or very small objects, or a nice surface finish, are as easy on a consumer grade 3-D printer. The required object sounds like a little ring or tube. You need a good measurement of the inner and outer diameters and the length. With that, it would be fairly easy to make a 3-D model, but you might still have to do finish work to make sure it fit firmly over the mirror support. Finding a piece of nylon tubing, wire insulation, or similar with the correct dimensions may make a better part.

reddesert said:

Finding a piece of nylon tubing, wire insulation, or similar with the correct dimensions may make a better part.

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That would be my plan too. Use different spacers to set the focus just like any other camera. Put it up on a tripod focused to infinity w/ the lens on B. Sort of a fiddley process but it should go quickly.