Disassembly and cleaning of an old Dallmeyer 220mm brass lens.

[MilesLilley]

Hello,
I recently acquired this old JH Dallmayer 220mm brass lens in an auction with multiple antique cameras and accessories. I’m very happy with this purchase and intend to use it with an old wooden large format camera, but as of now it’s in a way too poor condition to make any decent photos with. Luckily, it seems as if it’s only “dirt” and not haze, fungus or any other unwanted lens disease.
My only problem is i can’t figure out how to remove the glass or the “iris” so i can access it and clean it thoroughly. Any ideas on how to remove the glass, or easily access it?

Also, I’ve been wondering if it’s even a complete lens. There’s no front glass, but I’m not sure if there’s supposed to be? And will it even be functional as is?

Last, does anyone know what causes the black spots on the brass, and if it’s possible to polish away? I’m worried it might just make it worse.

Hope someone can help me get a bit wiser about my new lens!

Thank you,
Miles

221102 221103 221104221105

[MilesLilley]

221106 221107

[Greg]

Educated guess is that it's a single Meniscus with the front open "aperture" being the iris. Can you read the "No" # and the patent year?

[MilesLilley]

The number's "11855" and patent says "I".
Thanks.

[Greg]

The number's "11855" and patent says "I".
Thanks.

(less than educated) guess.... 1865 Rapid Landscape f/15 Meniscus lens

[Steven Tribe]

MY, my, someone local!

Here is the extract from an 1880’s Dallmeyer catalogue showing the relevant meniscus lenses.

There are two versions of this single meniscus - those labeled “patent” are the wide angled (slightly!) and these are the versions that you have the size “1” on your UK camera!

Size “1” has a focal length of 7” and covers 7 1/4” x 4 1/2”. So your camera is probably 1/2 plate size.

I am not surprised you have difficulty with the rear lens as the construction is slightly different from usual. The lens is attached to a section of the barrel with the male thread for the barrel.
I enclose a photo of my WA landscape meniscus size 5a dismantled.
If the balsam needs to be replaced, you will have a lengthy servicing procedure in front of you, as the lens is sealed into the brass mount.
The front aperture section screws off at the interface between the black enamel section and the brass barrel.

[MilesLilley]

What a coincidence!

Thank you very much for the reply Steven. I suspected the glass could unscrew from the main brarrel, but gave up since I couldn't get it loose. Looking at your lens it seems as if it's meant to unscrew, but unfortunately mine's stuck.

Any idea on how to loosen it - is there any lubrication you can use without damaging the glass?

Thanks a lot.

[Steven Tribe]

Glass is extremely resistant to chemical damage. Lenses which have been left to rot in out houses for decades get awful “patina” on the brass but glass remains almost as new.

Brass/brass threads do get very tight. There is no problem in using a proprietary liquid like WD** - helps to warm the barrel a little!

Or you could go to best method straight away - using a carefully controlled impact in the anti-clockwise direction.
You afix a motor hose clamp as near to the “join” as possible. Select the direction so that the best flat area to strike with a small hammer would be in the anticlockwise direction. Place a rubber gasket (cut from an old cycle tube?) between the clamp and the brass. Single blows with the hammer should do the trick to loosen the thread. Remember to clean both threads before reassembly. This sort of tangential impact will not stress the glass.