radioactive glass used in Leica lens in 1950s

[shaozhuohong]

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Hi, I heard that there was a kind of radioactive glass used in Leica Summcron-m 50mm lens around 1950s. Because of its radioacvtie, Leica built a factory in countryside for it.

 

I am not sure the type of the lens and, will it make bad effect to its users health?

 

Thanks!

[jaapv]

No - it will not even fog film. It might be harmful if you grind it up, suspend it in fluid and inject it, though. The factory Leitz built was in Canada. It had to do with radioactivity, but in another way. That was at the height of the Cold War, with middle Europe earmarked as a nuclear battleground. Leica feared Wetzlar would turn into a permanently radioactive dust bowl and wanted to secure its heritage. USA defense orders were another consideration.

Edited March 18, 2009 by jaapv

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[earleygallery]

How else are you going to get the famous 'Leica glow' ?

[lars_bergquist]

It's not Tom Lehrer's famous "beautiful radioactive glow" in the song 'We'll all go together when we go'. Its a combination of undercorrected spherical aberration, residual chromatic aberration and flare---in short, optical imperfection.

 

I can't understand why some people complain about its absence in modern Leica optics. It can be had fairly cheaply by the purchase of a 1950's M lens in good condition. A good candidate is the 2.8 50mm Elmar, which can be had for less than 200 euros.

 

The old man from the Age of John Foster Dulles (and Joe McCarthy)

[TimF]

How else are you going to get the famous 'Leica glow' ?

[earleygallery]

A good candidate is the 2.8 50mm Elmar

 

Argh, I have one of these. I shall call the authorities as soon as I get home. Don't think I'm going to be popular with the neighbours when they get evacuated tonight.......

[dkCambridgeshire]

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I have a few old 50's Leica lenses including the 50/2.8 Elamr and am wondering if they are radioactive. I enquired about a geiger counter in Maplins but they do not stock them

 

Cheers

 

dunk

[wizard]

Argh, I have one of these. I shall call the authorities as soon as I get home.

 

James,

 

Lars was refering to the famous Leica glow, which is not - as you will know - in any way associated with the use of radioactive glass in Leica lenses. Your Elmar 2.8/50 has no radioactive glass in it. The only lens I know of that used radioactive glass (from Chance Brothers) in the beginning was the first version Summicron 50mm lens. Later, new optical glass was developed rendering the use of radioactive glass unnecessary.

 

Regards,

 

Andreas

[gyoung]

James,

 

Lars was refering to the famous Leica glow, which is not - as you will know - in any way associated with the use of radioactive glass in Leica lenses. Your Elmar 2.8/50 has no radioactive glass in it. The only lens I know of that used radioactive glass (from Chance Brothers) in the beginning was the first version Summicron 50mm lens. Later, new optical glass was developed rendering the use of radioactive glass unnecessary.

 

Regards,

 

Andreas

 

Thats a relief, I have had a 2.8/50 elmar for 40 years, the Mk 1 Summicron for only 20.........

I wonder if it will make my M3 glow in the dark

 

Gerry

[veraikon]

No - it will not even fog film. It might be harmful if you grind it up, suspend it in fluid and inject it, though. The factory Leitz built was in Canada. It had to do with radioactivity, but in another way. That was at the height of the Cold War, with middle Europe earmarked as a nuclear battleground. Leica feared Wetzlar would turn into a permanently radioactive dust bowl and wanted to secure its heritage. USA defense orders were another consideration.

you are just kidding Elcan was founded because Wetzlar is about 1/2 h cardriving distance from battleground zero (Bad Hersfeld-Kirchhain) - where both east an west aspected one of the greatest tank battles if cold war became hot.

You are mixing up

Later on Elcan was used as manufacturing place because EU dammed Be contenting glass- Canada not Be is a toxic element - you need it for some special glases (Noctilux)

 

Concerning radioactivity the elements Lanthanium and traces of Thorium (@Lanthanium) are responsible

Both elements wer are also in some special glasses who were used in the 50/60ies for "fast" lenses.

La has atomic weight 57 and has two isotopes. One is non-​radioactive and dominates 99,92 percent of the time. The other is the radioactive La-​138 that comprises the leftover 0,08 percent. La-​138 is a Beta-​minus radiator, meaning that it emits electrons with a waylength (in air) of about 1 metre. La is also toxic.

 

see also Alfred Klomp (here Industar 61L*/D) * L= Lanthanium

ACP - Radioactive FED

 

Lanthanum - Wikipedia, the free encyclopedia

Thorium - Wikipedia, the free encyclopedia

[jaapv]

you are just kidding Elcan was founded because Wetzlar is about 1/2 h cardriving distance from battleground zero (Bad Hersfeld-Kirchhain) - where both east an west aspected one of the greatest tank battles if cold war became hot.

You are mixing up

 

 

 

That is exactly what I said:confused:

[veraikon]

That is exactly what I said:confused:

yea - didn´t you notice my smiley. The building of Elcan was decided in the early 50ies (1952?) when the atomic szenario wasn´t as realstic like in the 70ies/80ies (Hattenbach Ground Zero). In this time "outre rhin" (Germany , Netherlands , Danmark east of the Rhine) would be given up and Wetzlar was "outre rhin"

[StS]

... La-​138 is a Beta-​minus radiator, meaning that it emits electrons with a waylength (in air) of about 1 metre. La is also toxic.

 

Thinking about it. The Summicron of my M3 was built in 1954. The half life time of La-138 is 1,05 · 10^11 years. I should refrain in the near future from swallowing it or using Jaap's method...

Edited March 18, 2009 by StS

[jaapv]

yea - didn´t you notice my smiley. The building of Elcan was decided in the early 50ies (1952?) when the atomic szenario wasn´t as realstic like in the 70ies/80ies (Hattenbach Ground Zero). In this time "outre rhin" (Germany , Netherlands , Danmark east of the Rhine) would be given up and Wetzlar was "outre rhin"

 

Those were indeed scary times...

I did see the smiley, but failed to interpret it...

[rob_x2004]

So why does the paint fall off my MP?

[budrichard]

Non-issue,

these are termed 'soft' beta emitters which are basically stopped by a sheet of paper. One of the most sensitive organs to beta emission is the lens of your eye but the camera effectively stops any beta ray from the lens from contacting your eye.

The toxicity of La is for internal ingestion and has nothing to due with the element being present in the glass material.

In todays world of trying to capture your attention, these so called experts make it seem like any and every amount of radiation or exposure will be deadly which is not just the case. Your exposure to medical radiation in your lifetime will be the most concern to you.

BTW in the USA the amount of medical exposure is not regulated by the NRC but determined by your phsician but is only regulated by the NRC to assure that the machines work properly and you get what is desired and the sources and machines are correctly controlled.

Worry about your 'radioactive' lenses is a non-issue.-Dick

[rob_x2004]

So how do you explain the incidence of cancer in so many of Leicas new born?

[veraikon]

Non-issue,

The toxicity of La is for internal ingestion and has nothing to due with the element being present in the glass material.

I never suggested that old lenses wit La-bearing glases are radioactive or toxic. (see link of Alfred Klomp)

But both charcteristics (major the intoxination at the production processes (dust) than the radiactivity) are one of the reasons why manufactures tried to substitute some sorts of glas

[budrichard]

I never suggested that old lenses wit La-bearing glases are radioactive or toxic. (see link of Alfred Klomp)

But both charcteristics (major the intoxination at the production processes (dust) than the radiactivity) are one of the reasons why manufactures tried to substitute some sorts of glas

 

It is said that a little knowledge is a dangerous thing.

From your source, " around six to eight ion*i*sa*tions per ten sec*onds."

 

A Geiger Mueller tube(GM) counter is a gross instrument and 6-8 inonizations per 10 seconds is not statistically significant so whether actual radiation or something else is being detected is really not determined but in any event assume that there were that many disintegrations per 10 second detected by the tube. To have knowledge of the actual level of radioactivity one needs to calculate/determine the counter efficiency. The GM tube is only used for groos indications of radioactivity from beta, gamma rays. It can't detect alpha(usually) or neutrons. A much better instrument is the multichannel analyzer hookd up to a crystal detector which can record not only the peak energy but number of events over a time period(integration)..

 

"Most tubes will detect gamma radiation, and usually beta radiation above about 2.5 MeV" from Wiki and from your reference on La the maximum beta energy emmited by La is 1.044 Mev, so a GM tube is not an instrument for determining if radiation from La decay is present as the beta particle energy is too low.

 

Your quote " La is also toxic." would lead one to believe that you meant the glass was also toxic. If that is not what you meant then be precise.

 

In any event La in lenses is still a non-issue.-Dick

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Hallo,

Look here: Interesting Leica gear

[luigi bertolotti]

If some of you can read Italian, this is a deep examination of the "radioactivity issue" in lenses; the author is professionaly engaged in lenses design:

http://www.luciolepri.it/lc2/marcocavina/articoli_fotografici/articolo_obiettivi_radioattivi.pdf

 

The typical "radioactive lens" in Leitz history is the first Summicron 50, owing to the process of coating (the yellowish hue of the first Summicrons coating is really unique, and revealing... )

Edited March 20, 2009 by luigi bertolotti