What to do with a damaged lens

[Dave Moeller]

I have sitting in front of me (I was going to say "in my hands" but there's no way I could be typing and holding this lens at the same time) a 520mm f/10 Rodenstock Apo-Ronar. I got this lens when I purchased a 480mm APO Nikkor and the seller tossed this one in with a note that the rear element needed a cleaning.

Well, I don't think I'll be able to clean the rear element, as the problem with it isn't dirt on the surface but rather pits in the glass. Lots of them. It looks to me as if this lens was caught in a sandblasting. What first appears as white spots on the glass are revealed on further investigation to be pits into the surface of the glass. There is a small section of the glass near one edge that escaped the damage (as if it had been shielded from whatever happened to the rest of the lens surface by whatever piece of equipment the lens was mouned on).

Without even mounting this lens I can already tell that these are not the types of imperfections that sellers love to say, "...won't affect image quality." In fact, I'm quite sure this much damage will act as a destroyer of contrast.

So, short of use as a paperweight (with great conversational value), is it worth trying to do anything else with this lens? It's too unweildy to mount in a shutter without great cost, so I'm not really looking for a solution that involves spending much money such as having the rear element replaced. But is it worth trying to fill in the pits with india ink (a supply I have on hand for my calligraphy work)? If so, just how does one go about filling so many small pits without blackening the rest of the lens?

I know this seems like a question best answered by, "Hey, you've got a nice doorstop there.", but I don't want to miss anything obvious before I write this one off.

Thanks in advnace for your help.

[j.e.simmons]

You don't say if the lens is in a barrel or if you have just the loose elements. If in a barrel, I'd make up some kind of lensboard (mat board and tape), make something to act as a shutter (mat board in front of the lens, a hat, a hand) and make a negative. See what happens. If I didn't like it, I'd try filling the pits with ink from a sharpie - I don't think India ink will stick to the glass. Perhaps I'd try filling only a few large ones at first.

If you just have the loose elements, try to arrive at a guess about spacing and make your own barrel. You won't have a sharp image so accurace is not particularly important.

In other words, try it (channeling Fred.) juan

[Jorge Gasteazoro]

This is out of left field, but at ths point you have nothing to loose.

I dont know what is the optical refraction of gelatine, but certainly it sound like you could coat the lens with a thin coat of gelatin, drop it in formalin to harden and prevent fongus formation and see what happens. Of course this can only be done if you can remove the rear element, I certainly dont mean for you to drop the entire lens in the solution.

[Henry Ambrose]

Maybe Focal Point can polish the lens element?

[Ralph Barker]

I'm not an optics expert, so I may be talking through my hat here, but I'd think that pits on the rear element would act much differently than the same sort of pits on the front element. That is to say, rear element damage may affect the optical quality by strewing tiny bits of the image around, but it's not going to be bouncing light around between the elements as the same damage on the front element would. Thus, I, too, would be inclined to try it, and see what sort of images it produces. Nothing to lose but a couple of pieces of film and some time.

Depending on the test results, and what use you might have for that focal length, explore other options. If the pits are fairly deep, it may not be feasible to polish the rear element, but it probably wouldn't hurt to contact Focal Point as Henry suggested. Compare the cost of repair/improvement to the value, and you probably have your answer. Worst case is the paperweight idea you had to begin with.

[Paul Ron]

Once upon a long time ago I had a scretched lens which I thought was dead in my book. I took it to an optitian friend and he said blacken the scretch so it doesn't refract light and it won't effect your image since it just acts like a stopped down lens.

If your dents or scratches are very severe, consider getting in touch with the manufacturer and see if you can buy a new rear element or perhaps advertise for a broken lens you can canabilize for the part, it may be cheaper too.

Just a thought.

[Jim Rhoades]

First I would mount it to a plywood lens board. Then test it on some romantic flower type still lifes. It might be fuzzy enought to start you on a whole new photo project. Next try removing the rear and testing just the front. You might have a real neat 800 something lens. Add about two stops to the exposure.

[Brian Ellis]

I'd give it a try with a homemade lens board. Who knows, the images might be interesting. Sally Mann has done alright for herself using damaged lenses, why not you?

[Capocheny]

Dave,

You've certainly received some good advice here and I'd suggest the same thing... mount the lens and expose a few sheets of film. If you get positive results, then great!

If the results are positively god-awful, then what have you got to lose by trying some of the recommended solutions.

I was watching television the other night when an ad came on about a "lens pencil" that would fill in little scratches on your eye-glasses. I don't know if this would work on reducing the number of pits in your lens but, at CDN$21.95 (?), there's not much to lose. I didn't get the name and telephone number (since I wasn't personally interested) but I'll watch for the ad and if it comes on again... I'll take the info down and post it here.

Good luck.

Cheers

[Dave Moeller]

Thanks everyone for your suggestions. I had an extra blank plywood lens board here for my Cambo (does anyone actually buy lens boards for these things?), and an examination of the lens revealed that the front element had a "surround" on it that screwed off and that would screw onto the rear of the lens. With careful measurement and cutting, I've created a plywood board onto which the lens will mount using the surround from the front lens group screwed onto the back. The black paint is drying on that lensboard now, and I'll probably have time tomorrow (back pain allowing) to set up the camera and lens for some tests.

I hadn't thought about trying to shoot with only the front elements (which are in pristine condition); since I already have the Nikkor 480mm and I only shoot B&W, having a reasonable 800mm might be a very good thing.

Again, thanks!