turner-reich 12" convertable antastigmat fungus removal

[lloyd goode]

i can not figure out how to remove lens cells from the barrel so i can clean between the elements. Are they glued in? No apparent slots for the wrench that I can find. .Any help would be greatly app.reciated.

[Ron in Arcata California]

TR convertible lenses do not have air spaced elements. As well the lenses are held in place by rolling the brass rim down on end facing inward. The rim is not easily removed but can be done in a lathe. I have re-cemented TR lenses but it ain't easy.

[Don Dudenbostel]

It’s a tricky procedure to do this. About 45 years ago I had a neighbor that was a precision machinist and specialty optical builder for the department of energy. He designed optical systems out of non browning glass to be used in high radiation environments such as inspecting experiments running in the core of nuclear reactors.

My Turner Reich convertible like virtuall all the others had balsam crystallization in both cells. My friend successfully removed the cells but while slowly heating the cell to soften the balsam one element cracked.

I think some people have had success getting the elements apart soaking the cell in acetone and other solvents for a week or so so it might be easier and less risky that way. Once you’ve gotten them apart you have to get the cell back together in alignment. I believe there are 4 elements per cell which makes reassembly properly very difficult.

[Nodda Duma]

Turner Reich Anastigmats are 10 elements in 2 groups. Kind of like a Dagor, but two additional pieces of glass bonded on to get around the Dagor design patent and still provide similar level of correction (hence 5 elements per group instead of 4). On earlier TRA’s, the barrels are turned down ie burnished to retain the lenses on the ends closest to the shutter. Post-WW2 or WW2 era lenses (not sure when) changed to threaded retainers.

To remove the glass, the burnished part of the barrel has to be cut away carefully on a lathe. Then the lens can be pushed out and serviced. The burr on the cut metal treated with a chamfering tool to allow easy replacement of the repaired lens. If done right, the cut away burnished ring can be kept and reused, the cut away metal replaced with epoxy.

I’ve restored quite a few of these, like this one which was totally occluded by balsam separation.

[Michael Roberts]

Woo Pig! That is some beautiful glass!

[Nodda Duma]

In the example you just posted there is a threaded ring on the front of the glass in the barrel. Can that not be removed and the glass pushed out for recementing?

Absolutely not! That is not a threaded retaining ring at all. The “threads” are stray light reducing baffle cuts. The barrel is one solid piece of brass.

An internal centering ring sits around the second half of the group, inserted with the lens before the barrels were burnished down over the ring, preventing the glass from damage when doing so.

See sketch. Not my best but it’s been almost 30 years since I worked in a drafting department.

[lloyd goode]

Thanks for all the information and the drawing. Now I need to figure out if what I thought was fungus is really balsam crystallization. I can probably live with crystallization, not fungus.

[Nodda Duma]

Thanks for all the information and the drawing. Now I need to figure out if what I thought was fungus is really balsam crystallization. I can probably live with crystallization, not fungus.

Knowing that lens it’s likely balsam. They almost universally suffer from it. If you post a good picture I can tell you pretty quick.

[paulbarden]

Mine has a mild case of balsam separation, so I've left it alone:


The issue with mine is that 2 of the shutter blades in the Acme shutter have broken and come out of the shutter. That doesn't stop me using it though!
Its a fine lens, capable of doing excellent work. https://live.staticflickr.com/4882/4...c91df46f_h.jpg

[Tin Can]

I had 2 of them in my hands, very cheap, medium balsom

I made a mistake and did not obtain them both

The triple feature...

I NOW have an original catalog which shows how to use them

Live and learn