View Full Version : CLA for a Rodenstock Geronar?

Stephanie Brim
28-Apr-2008, 19:46
So I got this lens. Yes, another one. Beside the point.

The Copal 1 shutter is working fine, but the lens has fungus. A decent amount of it. I don't want to wreck the lens, which I think has potential, or the shutter.

Considering I got this for free (it was just sitting, apparently, and not getting any use), I'd kind of like to try a DIY fix. I was rereading a thread on APUG about another person's trials with a cheap lens and I have a few questions.

The first of which is the big one: is the lens worth trying to get it back to original condition? I've heard mixed opinions on the Geronars and I'd like to hear some more.

The second is what will happen if the first question is answered as I hope it is: how can I go about fixing this without running the risk of harming the lens or the shutter?

If you don't think I should do this myself, could you kindly recommend a lens CLA person? I know that Carol Flutot is really good, but I don't want to add to her increasingly large workload just as she's getting back into things.

Edit: But she only works on shutters, doesn't she? Crap.

Wayne R. Scott
28-Apr-2008, 19:53

Can you unscrew the front and rear lens cells from the shutter?

If so you can soak them (the lens cells, not the shutter) in household ammonia cleaner. This should kill the fungus, but there may be damage to the lens coatings from the fungus "tracks" left in the coating.


Stephanie Brim
28-Apr-2008, 20:11
I can get the back, but not the front. Dunno why. There are spanner holes, or what I think are spanner holes, on the inside of the front ring. I don't have a spanner (yet). Hrm.

Stephanie Brim
28-Apr-2008, 20:15
Er, haha, got it. I knew I kept a pair of sharp point scissors around for some reason. ;)

Ammonia, I don't have any ammonia. I don't use that, either.

Michael Darnton
28-Apr-2008, 20:21
I would stay away from soaking them in anything liquid, unless you intend to recement the elements back together after they come (partially, probably, making a mess) apart. And in cleaning, be careful, too, to not let anything sneak around the edges and back inside. Acetone is the absolutely worst thing you could use in this regard, along with all the common solvents, like alcohol, turpentine. . . just about anything from the hardware store that's not water.

I've had good success cleaning fungus with just windex, used sparingly. Put it on a piece of tissue, not directly on the lens--stay dry! It won't take off the etching of the glass that fungus causes (nothing short of a real professional polishing will, I don't think), but it does a pretty good job. After that, you might follow up with fresh distilled water from the grocery store. Don't grind too hard; it used to be that inner coatings were softer than outside ones, which needed to be harder. I don't know if that is still the case or not.

Stephanie Brim
28-Apr-2008, 20:36
The issue is that it's not on the front of the element, such as in the coating, it's in between the cells. I think. Judging from looks, anyway.

Michael Darnton
28-Apr-2008, 20:45
The most likely spots are the back of each component--the glass right next to the diaphram/shutter on either side. The other possible spot is an airspace between elements, and though one of the Geronar components is a single element, the other an uncemented pair, so I suppose it could be between that pair, but that seems less likely.

Since you don't have any cemented elements, I guess the worst that could happen is that you could turn your lens into an expensive bubble level. :-) Anyway, don't soak anything. Another thing that can happen with solvents is that many (alcohol and acetone, for instance, and also strong ammonia) will strip the blacking off the edges of the elements, and the lettering off the front.

28-Apr-2008, 21:00
Alex Wei helped me re-cement my cells on a tessar. It's not for the faint of heart, but boy did it make a difference. I'll describe the process, and warn you that this is for entertainment purposes only:

1) Remove the cells from the metal barrel; you'll need to have ONLY the cells free with no metal casing.
2) You need to mark the sides of the cells with something permanent that won't come off easily. Alex suggested etching it with a sharp metal object, or using a marker. This is important because when you put the cells back together, you need to line up these marks.
3) Put the lens in a cold oven and set the temp to 300 degrees. :) Put the lens in the oven in some kind of heat-proof dish so that the balsam doesn't leak all over your oven.
4) Every few mins, fetch out the lens with a hot mitt and see if you can pry the cells apart. You shouldn't have to use a lot of force - if they don't come apart, put them back in the oven and wait some more. BTW, you'll notice a nice "pine" smell begin to emerge from your oven. This is the balsam melting. The lens will not look pretty at this point. Please note the LENS WILL BE HOT. So don't touch it with anything but a mitt.
5) When you finally get the cells apart, let them cool. To clean them, I used nail polish remover, which will probably strip any coating and fungus from the cells. Oh, but they'll sparkle!
6) When the cells are squeaky clean, clean them AGAIN with rubbing alcohol. You need to make sure that when you're done there's absolutely no residue left on the glass.
7) Apply a very, VERY small dot of ultraviolet cement onto the center, concave element of the lens. VERY carefully, put the convex element on top. Leave this for a few minutes, and you'll begin to see the cement ooze out toward the edges of the elements. Make sure the marks you made on the side of the elements line up.
8) When it reaches the edge, CAREFULLY pick up the lens and look for air bubbles. Found some? Clean the lens again and repeat step 7.
9) When the lens finally meets your satisfaction, or hell, you're just too frustrated to try again, it's time to set the elements. Put the cells in between two metal V-blocks, still ensuring that the marks you made on the side line up. Carefully whip out your trusty handheld UV lamp, and place it over the lens, careful not to disturb the elements. Turn it on, and leave it for an hour or so.
10) Repeat with other lens elements if required.

Another cautionary note: UV cement does not come off in the oven if you screw this up. You're essentially going to be stuck with a useless lens.

As freakishly scary as that sounds, Alex did a wonderful job with my free 5x7 Tessar, and I learned a helluva lot from him that afternoon. So my last bit of advice is: Have someone around who has done this before! In the end, you may just be rewarded with a clean shiny lens that looks like new, probably "sans-coating". But if the lens was unusable in the first place, that's a heck of a step up!


28-Apr-2008, 21:01
Since you don't have any cemented elements...

Oh, sorry, then disregard my post. Still a fun project if you ever find one that HAS cemented elements.....


Stephanie Brim
28-Apr-2008, 21:10
Dunno what the other lens I bought (http://www.largeformatphotography.info/forum/showthread.php?t=35636) will have until I see it. So your information may still prove valuable.

Now...how do I go about extracting the cells? I'm probably going to need tools I don't have at the moment. I'm guessing my local hardware store won't have a spanner wrench in the size used for this.

Jon Shiu
28-Apr-2008, 21:23
Hi, I have the same lens (actually relabled as Caltar IIE 210mm f6.8) and it is a very sharp lens when stopped down.