WW4

I'm brand new here and joined this forum specifically for this question, though it looks like there's enough good information here to stick around.

I'd love to replace (or refurbish) the front glass in a 700mm lens my grandfather had made in Berlin after WW2. Beyond the sentimental value, it's a cool lens and would be fun to see if I can get photos through it with my DSLR. The glass is so damaged and frosted now. The lens was for an Exakta mount and I've found an adaptor for my canon. I've had no luck searching on-line, though I'm not really sure what the right search terms would be. Any help or direction would be very appreciated.

RWR Loc: La Mesa, CA

I would ask a camera repairman where to take it for recoating or replacement.

mas24 Loc: Southern CA

You may have to get in touch with someone who specializes in restoring vintage glass. I remember many years ago, I knew someone who had a set of American military binoculars from WW2, and he sent it out to replace a glass, and it came back almost like new. Good luck.

tripwest Loc: Rochester, NY (Kodakland)

Very cool. I'm having my grandmother's dictionary and my grandfather's bible both rebound. I appreciate your sentimentality. Plus, it's just very, very cool.
Do you know who made the
lens in Germany? Who was the manufacturer or craftsman? Is it marked or labeled in any way?

Ich liebe mein Nikon-Glas

-TJ

robertjerl Loc: Corona, California

If he had it made custom than unless polishing and coating will do it the only way would be to have a custom ground element made. I doubt your local Lens Crafters would do it. Maybe someone who makes telescopes. You might have luck contacting a museum that has a large collection of telescopes, cameras etc.
I googled "custom lens elements" and got a bunch of hits, skimming their site blurbs my wallet started aching because they did not mention any prices. Like the man said about his yacht, "If you have to ask, you can't afford it!"

Erik_H Loc: Denham Springs, Louisiana

Welcome aboard!
You should post pictures of the lens, we'd all love to see it. If you check the store original box when you upload pics here we can see them full sized.

JimH123 Loc: Morgan Hill, CA

I don't really think this is a very achievable. Unless you can find an exact replacement, I don't think that you are going to get a custom lens manufactured. I did take a look at Edmund Scientific:

https://www.edmundoptics.com/optics/optical-lenses/#f=Categories_ss|1647

They sell all sorts of lenses, but I didn't see anything with a focal length that long. They do offer Achromatic Lenses and go up to 400mm FL, but it is f16. But Achromatic, with 2 elements, doesn't properly correct for all light wavelengths, and instead, Apochromatic lenses, with 3 elements, do a better job.

For comparison, I have a telescope that has a FL of 710mm at about f7 that can take a really good image, an Explore Scientific ED102. Now it is not something that you can hand hold, and it actually takes a very robust tripod to hold it.

As an idea of what a 700mm (actually 710mm) lens can do on a full frame camera (Sony A99), I am posting a picture of a farm house at a distance of 3.6 miles taken through this Explore Scientific ED102. The image is not vignetting. There were some low hanging branches I was shooting under.

(Download)

JPL

You should contact some one with experience and see what they think they can do, if the lens can be cleaned or if it has to be rebuilt. What do you mean when you say the lens is damaged and frosted? Is it scratches in the glass or just dirty and with fungus? Check first if that is the problem, then it is easily fixed.

http://thecinelens.com/2011/11/01/vintage-lens-restoration/
http://www.midwestcamera.com/index.html
http://www.apertureuk.com/camera_repairs_london.html
http://photoethnography.com/ClassicCameras/repair.html

But if you need to replace some of the optics in the lens you may have to deal with companies like this one.
http://www.janostech.com/products-services/solutions-capabilities/optical-components.html

cthahn

Not feasable.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

https://thecinelens.com/2011/11/01/vintage-lens-restoration/ or https://www.noisebridge.net/wiki/Cleaning_and_restoring_vintage_cameras or http://www.zeissikonrolleirepair.com/

kymarto Loc: Portland OR and Milan Italy

Can you tell us the lens? Sounds like some kind of lens for aerial reconnaissance perhaps.

I seriously doubt that you can get a replacement element made. First you would need to exactly match the curvature, but beyond that you need to know the type of glass as the index of refraction must also match precisely. Without the original maker's design specifications (usually kept secret) you are out of luck.

If this were a very rare lens in a more usable focal length it might be worthwhile to investigate further, but 700mm is not a highly desirable focal length for users of vintage glass. My guess is that it will cost in the neighborhood of $10K if you want to attempt it, as it is very specialized work for which very few independent contractors are qualified.

Another option is to find a similar lens on eBay with problems but a decent front element and swap that out. Also it is important to know exactly what the damage is. Damage to the front surface can sometimes be rectified by repolishing, but deep scarring will foreclude that possibility, as in that case getting rid of the problem will change the curvature of the lens.

Many lenses have a cemented doublet in front, and you can get problems of delamination and fungus/haze on the inside. All these problems can be fixed, although delamination requires that the elements be recemented, which is specialized work and will not be cheap.

jerryc41 Loc: Catskill Mts of NY

Welcome to our forum!

JPL and billnikon gave you some good links. Any company will want to examine it first, and that will involve shipping it back and forth to different dealers, so be prepared for that. If your goal is to use the lens for photography, you may not be getting the most for your money. A modern lens would most likely be better than one made decades ago, and it would cost a fraction of what a restoration would cost. Keeping it for sentimental reasons - as is - would be a smart move.

WW4

Great information everyone. Thank you!
I will have time to follow some of the links later.
Old photo of lens and Grandpa Bill attached.

The lens has an internal aperture (black ring in the photo) and the front element is the only glass. It's a big aluminum tube with a lens at the end. The design is the source of its demise. At some point in the past, it must have been stored under a bed or a workbench laying on its side, hen stood up on end to store in a closet with no regard for the poor mouse who had crawled in. The mouse was still there decades later when my father and his brothers cleaned out the family house. It was passed on to me a few years later. No one had noticed the mouse yet--just knew it needed to be cleaned. I love my family.

The glass has some scratching on the outside. (I don't know if it was ever boxed or stored correctly. If the box in the background of the photo was for this lens it's long gone now.) The inside of the lens was also very dirty with decades of dust, mouse mummy and who knows what fugal or bacterial cultures along the way.

The lens is marked BOYER PARIS SAPHIR 1:6.3 F:700 No. 145542
On-line searches have yielded references to the company and lenses made by them. However, I have found nothing close to matching this lens, though I might not have the right search parameters.
The family story was that he had had it custom made while in Berlin). Family stories often lose (or add) details so I'm not sure of the actual history. He was a horsetrader and a non-smoker. (There are other interesting stories about the things that could traded for cartons of army allocated cigarettes.) Maybe the actual story is that he traded for the lens and had it adapted to fit his Exakta. It has a military look to it. I've wondered about aerial surveillance too.

Thanks again for all of your interest and help.

(Download)

SharpShooter Loc: NorCal

WW4, welcome to the Hog!
That's a pretty unusual lens.
Call these guys, they should be able to handle anything you need done. I've never used them but have talked to them and it seems they are pretty good.
Good luck, and again, welcome!!
SS

http://www.focalpointlens.com/

Kuzano

Call and talk with John at FocalPointLens. He's done some great glass and lens repair for me. Well equipped and timely.

http://www.focalpointlens.com/

Also recommended by APUG (it's a large format users group) is S. K. Grimes, doing shutter and lens repair work for many years.

The large format user groups will have many more lens repair referrals than routine photography forum.

I'd start with FocalPointLens.