Yashica-C TLR; rear lens element orientation?

[ken_kuzenski1]

<p>This is a REALLY stupid problem to have, and I couldn't find a diagram of this on the web.   A Yashica-C was my first MF camera, years ago; I bought a 500cm shortly afterward and sold the Yashica--and I've regretted selling it since then.   I just saw a Yashica-C on ebay and bought it to put it on my desk at work--it was very cheap and the seller said the shutter was inoperative.<br>

I SHOULD have just put it on my desk but I couldn't resist having a look inside.  Took the lens elements out, and after a couple of hours of gentle cleaning, the shutter seems to operate pretty normally now.  So I'm thinking, of course, of putting a roll of film through it to see if it actually works.  My problem is that when I took out the rear element, the one behind the shutter, inside the camera, the lens hopped out into my hand and I can't tell which way it was in, which way it faced, inside the camera.  One side of the lens is essentially flat, the other is somewhat convex, ot bows outward.  This is the Yashikor 80mm f/3.5 lens.<br>

You'd think it would be easy to try it both ways and see which way produces a normal image at the film plane but I simply can't tell this way.  Is there a Yashica-C owner out there who would be kind enough to look and tell me if the lens face closest to the film, on the rear element, the one you can touch if there's no film in and the back is open, is flat, or if it's somewhat convex?  Many many thanks!   --ken<br>

 </p>

[dave_s]

<p>I've never had a Yashica, but your lens is a triplet. <br>

The standard orientation for the back element of a triplet is the flat surface faces towards the inside of the lens, and the convex surface faces the film gate.<br>

Run some film through it and tell us how it works out.</p>

[jonathan_bourla1]

<p><img src="http://images.google.co.nz/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Taylor-Cooke_Triplet.svg/180px-Taylor-Cooke_Triplet.svg.png&imgrefurl=http://en.wikipedia.org/wiki/Rollei_35&usg=__fN4zwZBUPTBFKPGOi4omVAxMn4c=&h=180&w=180&sz=6&hl=en&start=7&tbnid=FcnA34BHmcTNlM:&tbnh=101&tbnw=101&prev=/images%3Fq%3Dtriplet%2Blens%26gbv%3D2%26hl%3Den%26sa%3DG" alt="triplet lens" />Hi. I haven't got a Yashica C to check, and couldn't find the information on the net, but a generalised triplet lens has the convex surface of the rear element to the outside of the lens. Hope that helps. Jonathan</p><div></div>

[User_503771]

<p>First -- You're a brave man, Ken, and I applaud you!</p>

<p>To answer your actual question: I've never ever seen a lens of any configuration (outside extreme wide angles) in which the outside surface of the rear element was flat. If one side has a gentle curve, try that on the outside (point into the camera) first.</p>

<p>That diagram in the post above, I think, tells the story very well.</p>

<p>Good luck with the camera and its lens! Post some pictures when you get a chance.</p>

[ken_kuzenski1]

<p>Thank you all very much; I've put it back together in the orientation you suggest and we'll see if I manage to get some photos out of it!  Thanks!   --ken</p>