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Jelte
Tinkerer
Username: Jelte
Post Number: 1
Registered: 09-2012
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 19, 2012 - 09:16 am: | 
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Hi all,
I've recently bought a Meyer Görlitz Trioplan 100mm f/2.8 lens (three elements, 1960's). Unfortunately, yesterday one of the aperture blades went out of position. I now can only use f/4-f/22. It's like on this picture (A): http://www.flickr.com/photos/onthewings/5383520480/
In the comments on this photo I read that it should be not hard to fix this problem. Does anyone have tips to safely disassembly the lens and fix the aperture? I'm completely new to tinkering with lenses, so I want some information before I start with it.
Thanks in advance!
Jelte |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 218
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 20, 2012 - 10:36 am: |
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You probably don't want to read this, but it's the truth. My experiences with repairing lenses have taught me that almost no two lenses are alike when it comes to dismantling/reassembling them. After a while, you'll pick up a few techniques that will help you avoid dismantling them more than you need. In your case, apparently you want to reach the aperture blades, but no more. I'm not familiar with this lens, but the one you show in the photo is completely manual with no interaction linkage to have to worry about. Without seeing a photo of the actual lens that needs to be dismantled, I'm just taking a stab in the dark. But typically you're gonna need to remove a rear element to get to the aperture iris. Often to remove that rear element, a lens spanner is required. You'll know if you need one by looking for a couple of notches in the element's outer ring, 180 degrees apart. Go to eBay and do a search on "lens spanner" and you'll get over 100 hits. If you get one that looks something like this, it will be most useful for you:
http://www.ebay.com/itm/DSLR-DC-Lens-3-tip-Spanner-Wrench-Repair-Opening-Tools-/ 280690925425?pt=LH_DefaultDomain_0&hash=item415a7b9f71
If there are no notches on the rear element's outer ring, then look for them on the front element. If you don't see any there, they may be hidden behind the lens's bezel. Which can typically be removed/unscrewed with a correctly sized rubber stopper (for chemistry glassware). You can find these on eBay also. They're cheap. If you have to go through the front, pretty much the same thing applies, although things may get a bit trickier, since it's likely that the lens's front element assembly is engaged with the focusing helical. So you may end up having to re-position the lens assy for correct focus when you're done. It can wind up being *way*too*much*fun* if you're not careful. ;)
Once you have the glass out of the way, chances are you'll be able to reset the iris blade(s) with a good pair of tweezers and a healthy dose of patience.
Before you begin reassembly, inspect the inner surfaces carefully for signs of dust and/or fingerprints or smudges. Make sure they are spotless before putting things back together. |
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