Is this Mamiya C-series lens salvageable?

[rudy_bustamante]

<p> I have recently purchased a broken 135mm Mamiya lens for a song, to try my hand at disassembly and repairs. It hasn't arrived yet for me to assess the full damage, but I'd really appreciate some opinions. Is this an impossible task?</p>

<p> <img src="http://www.kisala.com/ebaypics2011/30353lenDSC09334.JPG" alt="" width="637" height="380" /></p>

<p> I've bought some phosphoric acid to try and get the rust off, but it looks like even if I get it off I might have to take the whole thing apart. Anyone have any links to Mamiya lens repair manuals? I've managed to Google myself one for C220 bodies, and a french blog on these lenses (that is unfrotunately rather difficult to understand, being computer translated and all)</p>

<p> Thanks for any help you guys can give, I mean it'd be nice to fix this but since it cost me a tenner, feel free to tell me if it's a write-off</p>

[bob_sunley]

<p>From a quick glance, that iris is is real bad shape. Hopefully there are no broken blades. I'll bet the shutter is as rusty. :(</p>

<p>It will be a good training lens for a how to repair. Don't forget to take lots of pics.<br>

.</p>

<p> </p>

[rudy_bustamante]

<p> The blades appear to have 'slipped their moorings', at my best guess, but I can't imagine what would cause them all to become so misaligned. I really am curious as to what it will look like on the inside</p>

[michael_madio]

<p>Looks like you will have to replace the blades and there's probably rust inside the shutter mechanism as well. Considering you can get a functional replacement for $79 from KEH it's probably not worth working on.</p>

[bob_sunley]

<p>http://pheugo.com/cameras/index.php?page=seikosha A web page on Seikosha shutters.</p>

 

[jenny_jaques]

<p>Occupational therapy. But hey .. assuming you're in the Northern Hemisphere ... winter has arrived. A cosy workshop, with radio, coffee maker, cat curled up near by, it would be a fun project to have.</p>

[chris_waller]

<p>Sheesh! That's had some rough treatment. A lot of patience might nurse it back to working condition.</p>

[len_robertson]

<p>Jenny has the right attitude here - have fun with it and learn about shutters. At worst, you will have a pile of parts you can sell on eBay. Bob Sunley posted a great link. Here are some I have Bookmarked:<br>

http://www.kyphoto.com/classics/forum/messages/6900/5653.html?1134189200<br>

http://www.kyphoto.com/classics/forum/messages/6900/5231.html?1127315771<br>

http://www.flickr.com/photos/27343061@N05/sets/72157612018312116/<br>

The Mamiya 135mm has the shutter exposed behind the rear lens element, so it is possible it got a couple of drops of salt water or something on the blades causing the rust. Then someone tried to operate the shutter, and the blades got out of whack. If you are lucky, the interior of the shutter might not be really bad. But you will need to disassemble it and look inside to find out. I'm sure I have seen posts on cleaning and polishing shutter blades. Probably for large format shutters, or iris diaphragms, so you may need to search for shutter repair other than Mamiya. I suspect the idea is to polish the blades, not scrape them, to remove the rust. As long as the blades aren't bent, they may be saveable. If you can find another Mamiya lens with horrible glass, you can probably swap shutters. I imagine a shutter from the easier to find 80mm will interchange.</p>

<p>Len</p>

[rodeo_joe1]

<p>Phosphoric acid doesn't dissolve rust, it reduces the metal oxide back to metal. The downside is that the lumpiness of the rust isn't reduced, and that the blackening of the blades will be replaced with shiny steel where the rust was.</p>

<p>It's my guess that the rust has stuck the blades together at one time, resulting in the displaced pivots that you see. It <em>should </em>be completely repairable unless one or more of the pivot pins has become broken or detatched from its iris blade. In fact looking at the picture more closely it appears that the pivots of the blades are simply pressed "pips" in the blades themselves - a crude way to do things.</p>

<p>As you'll doubtless find out for yourself, reassembling a dislodged iris blade is a frustrating and sometimes time-consuming business. You'll probably need to split the rotor and stator rings of the iris mechanism to realign the blades. The rotor is usually held in place with a spring retaining ring in a groove (a circlip). Get yourself a decent pair of non-magnetic tweezers, and good luck!</p>

[q.g._de_bakker]

Phosphoric acid turns rust into iron phosphate, which scrubs off. The lumpiness will be gone. But it may need repeated treatment to convert and remove it entirely.<br>But not something i'd do.

[ian_rose]

<p>Everbody has been talking about removing the rust from the blades once it has been removed re colour the blades with gunmettle colouring (black or blue).</p>

<p>Ian R</p>

[rudy_bustamante]

<p> Thanks a lot for all the suggestions, I'll post some pictures of my efforts when it arrives</p>

[jim_bielecki1]

<p>Just to be sure, are we looking at pictures of the shutter blades? Or the aperture? As pointed out before, this variety of Mamiya 135mm lens has the shutter and aperture located behind the rear elements so they're totally exposed to the outside (which is not a big deal once the lens is mounted on the camera). All other Mamiya TLR lenses have the shutter and aperture blades inside the lens.</p>

[rudy_bustamante]

<p> It's the aperture, the shutter has 5 blades. I'm really hoping the shutter won't be as bad, I'm a loss less confident tackling a messed up shutter. Though I've got another Mamiya lens that sticks at slow speeds so it'll be good practice before I give that a clean</p>

[flavio_egoavil]

<p>The shutter on these lenses is usually the same on many of these series. You have a good chance to buy another junked mamiya lens of the same era and replace the shutter assembly. Or buy another junked 135mm (i.e. with lens elements problems but OK shutter)</p>

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