Thorium lenses

[Tragg]

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I believe that some Leitz Summitar and early Summicron lenses used a glass formula that contained Thorium or Lanthanum, both of which are radioactive. I have spoken to a number of Leica dealers and have been told that it is hard to pinpoint exactly the serial number range they occur in, but that it is generally at numbers below 1000000. The consensus appears to be that these lenses do not present a health issue, but they do acquire a yellow or orange tint with age, which has an adverse effect if they are used with colour film. I am looking for a collapsible Summicron but want to avoid a radioactive lens for the reasons outlines above. Do you have any information that would help me identify one of  these lenses? Was Thorium or Lanthanum used for any lenses besides the Summitar and Summicron?

 

 

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[wizard]

vor 9 Minuten schrieb Tragg:

I am looking for a collapsible Summicron but want to avoid a radioactive lens for the reasons outlines above.

I have two collapsible Summicron 50 lenses, both in the 1 3xx xxx serial no. ballpark. They certainly do not have any radioactive lens element. The lens you are looking for was made in large numbers at the time, so just go for serial nos. above 1 2xx xxx, and you will be safe.

[Al Brown]

https://www.l-camera-forum.com/topic/79848-radioactive-glass-used-in-leica-lens-in-1950s/

https://www.l-camera-forum.com/topic/116793-radioactive-glass/

https://www.l-camera-forum.com/topic/7065-lanthanum-of-old-leica/

 

[frame-it]

21 minutes ago, Tragg said:

but they do acquire a yellow or orange tint with age,

which reduces when the lens is exposed to the sun for some time

 

Edited November 17, 2022 by frame-it

[zeitz]

1 hour ago, frame-it said:

which reduces when the lens is exposed to the sun for some time

Alternately a UV reptile light can be used.  I treated a Pentax 50mm f1.4 lens that has radioactive elements with the light.  It does take a weeks of exposure to remove the yellow.  A couple of Nikon lenses also have radioactive elements.

[frame-it]

 

 

[frame-it]

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25 minutes ago, zeitz said:

A couple of Nikon lenses also have radioactive elements.

yes, quite a few lenses actually

Lenses That May Contain Thorium or Lanthanum

• Kodak Ektar 101mm f/4.5 (Miniature Crown Graphic camera) lens mfg. 1946

• Kodak Ektar 38mm f/2.8 (Kodak Instamatic 814 camera) lens mfg 1968-1970

• Kodak Ektanar 50mm f/2.8 (Kodak Signet 80 camera) lens mfg. 1958-1962 (3 examples)

• Kodak Ektanar 90mm f/4 (Kodak Signet 80 camera) lens mfg. 1958-1962

• Kodak Ektanar, 44mm f/2.8 (Kodak Signet 30, Kodak Signet 50, Kodak Automatic 35/Motormatic 35 cameras) lenses mfg. 1959-1969

• Kodak Ektanon 50mm f/3.9 (Kodak Bantam RF camera) lens mfg. 1954-1957

• Kodak Ektanon 46mm f/3.5 (Kodak Signet 40 camera) lens mfg. 1956-1959

• Kodak Anastar 44mm f/3.5 (Kodak Pony IV camera)

• Kodak Color Printing Ektar 96mm f/4.5 lens mfg. 1963

• WEP Auto Weiton 35mm f2 

• Argus Cintagon 50mm f/2.8

• Agfa Color Solinar 2.8/50 

• Bell & Howell Director Series (Model 1208?) XL Super 8 movie camera; Zoom Lens f: 1.2 \ F: 9-22.5 mm

• Canon FL 50/1.4 (very early version) 

• Canon FL 50/1.8 I 

• Canon FL 58/1.2 

• Canon FD 17mm f/4

• Canon FD 35mm f/2.0 (versions from the early 1970's - concave front element)

• Canon FD 55mm f/1.2 S.S.C. Aspherical 

• Canon (SUPER-CANOMATIC LENS) R 50mm 1:1.8 

• Carl Zeiss Jena Pancolar 55mm f1.4 

• Carl Zeiss Jena Pancolar 50mm f1.8 "Zebra" (1964-67, up to serial number 8552600)

• Carl Zeiss Jena Biometar 80mm f2.8 "Zebra" "(Only P6 mount version )

• Carl Zeiss Jena Flektogon 50mm f4 "Zebra" "(Only P6 mount version )

• Carl Zeiss Jena Prakticar 50mm f1.4 (1st version with engravings around the outer side of barrel)

• Carl Zeiss Tessar 80mm f/2.8 (old silver Hasselblad version)

• Enna München Lithagon 1:3.5 35mm (M42) 

• Focal 35mm f/2.8

• Fujica Fujinon 19mm f/3.5 EBC (Arkku at mflenses.com)

• Fujica Fujinon 35mm f/1.9 EBC (Arkku at mflenses.com)

• Fujica Fujinon 50mm f/1.4 non-EBC early style

• Fujica Fujinon 50mm f/1.4 EBC early style

• Fujica Fujinon 100mm f/2.8 EBC 

• Fujica Fujinon 400mm f/4.5 EBC

• Fujica Fujinon 600mm f/5.6 EBC

• GAF Anscomatic 38mm f/2.8 

• Kodak Aero-Ektars 

• Kodak Ektanon 4-inch Projection Lens f/3.5

• Kodak Instamatic M24/26 Super 8 Camera YouTube

• Kodak Ektar 80mm f/2.8 (for Hasselblad 1600F and 1000F, made 1948-1950)

• Kodak Ektar 135mm f/3.5 (for Hasselblad 1600F and 1000F, made 1949)

• Konica Hexanon AR 50mm f1.4 (smallest aperture 16; green AE marking)

• Konica Hexanon 57mm f1.2 

• Konica Hexanon 21mm f4 

• Leica 50mm f/2 Collapsible Summicron

• Leitz Wetzlar Summicron 5cm f2 (M39)

• Mamiya/Sekor 55mm f/1.4 (m42, chrome+black, flat rear element) 

• Mamiya/Sekor SX 55mm f/1.8 

• Minolta MC W. Rokkor-SI 1:2.5 28mm (early variants)

• Minolta MC Rokkor-PG 1:1.2 58mm 

• Minolta MC Rokkor 1:1.7 85mm (the earliest variant of the MC line) 

• Mitakon (Zhongyi) 50mm f0.95 Ver I Speedmaster 

• Mitakon (Zhongyi) 50mm f0.95 Ver II Dark Knight

• Nikkor 35mm f/1.4 (early variant)

• Olympus Zuiko MC Macro 20mm f/3.5 

• Olympus Zuiko Auto-S 1:1,2/55 mm (first version)

• Olympus Zuiko Auto-S 1:1,4/50 mm "Silvernose" 

• Olympus Zuiko Pen F 1:1.8/38mm 

• Olympus Zuiko Pen F 1:1.4/40mm 

• Rikenon AUTO 55mm f/1.4 

• Schneider Repro-Claron 

• Schneider 135mm f/3.5 Xenotar 

• SMC Pentax 50mm f/1.4 

• SMC Takumar 20mm f/4.5

• SMC Takumar 35mm f/2.0 

• Super Takumar 35mm f/2.0

• SMC Takumar 50mm f/1.4

• Super Takumar 50mm f/1.4 (the latest version with 7 elements - red 'infrared mark' being on the left side of DoF scale '4')

• SMC Macro Takumar 50mm f/4.0 

• Super Takumar 55mm f/1.8 

• Super-Multi-Coated Takumar 55mm f/1.8 

• SMC Takumar 55mm f/1.8 (select lenses)

• Super Takumar 55mm f/2.0 

• SMC Takumar 55mm f/2.0 

• SMC Takumar 85mm f/1.8 

• Super Takumar 6x7 105mm f2.4 

• Steinheil Auto-Quinon 55mm f/1.9 KE mount

• Tele-Takumar 6.3 300mm 

• Topcor RE GN 50/1.4 

• Topcon UV Topcor 50mm f/2 

• Yashinon-DX 28mm f/2.8 (Yashica)

• Yashinon-DS 50mm f/1.4 (Yashica) 

• Yashinon-DS 50mm f/1.7 (Yashica) 

• Yashinon-DX 50mm f/1.4  (Yashica) 

• Yashinon-DX 50mm f/1.8 (Yashica) 

• Yashinon-DS-M 50mm f/1.4 (Yashica)

• Yashinon-DS-M 50mm f/1.7 (Yashica) 

• Yashinon-DS-M 55mm f/1.2 (Yashica) 

• Yashinon-ML 50mm f/1.7 (Yashica) 

• Yashinon 55mm f1.2 (Tomioka) 

• Ultragon 115mm f/5.5 

• Vivitar Series 1 28mm f1.9 

• Voigtlander 50mm Nokton Prominent

• Voigtlander 15cm Apo-Lanthar 

• Voigtlander 21cm Apo-Lanthar 

• Voigtlander 30cm Apo-Lanthar 

• Voigtlander Zoomar 36-82mm f2.8 

• Wollensak Raptar 28-75mm f2.3 

• Zenitar-M 50mm f1.7 

 

https://lenslegend.com/radioactive-lenses/

https://camerapedia.fandom.com/wiki/Radioactive_lenses

[Anbaric]

3 hours ago, Tragg said:

I believe that some Leitz Summitar and early Summicron lenses used a glass formula that contained Thorium or Lanthanum, both of which are radioactive. I have spoken to a number of Leica dealers and have been told that it is hard to pinpoint exactly the serial number range they occur in, but that it is generally at numbers below 1000000. The consensus appears to be that these lenses do not present a health issue, but they do acquire a yellow or orange tint with age, which has an adverse effect if they are used with colour film. I am looking for a collapsible Summicron but want to avoid a radioactive lens for the reasons outlines above. Do you have any information that would help me identify one of  these lenses? Was Thorium or Lanthanum used for any lenses besides the Summitar and Summicron?

You don't need to worry about Lanthanum in general, which is still used today and has very low levels of radioactivity. Natural lanthanum contains only a tiny proportion of a long-lived radioisotope. Lots of things we don't bother about also contain small quantities of radioisotopes, like potassium-rich foods (you can detect the radioactivity of a banana with sensitive measuring equipment). The only specific concern here is that some early batches of lanthanum glass may have a degree of thorium contamination, as suggested by Marco Cavina.

The Summitar does not contain thorium, but a small series of what are effectively pre-production collapsible Summicrons (which do contain thorium) were engraved "Summitar *". These are collectable and correspondingly expensive. The regular Summitar is a fine lens, especially if coated, and is usually easier to find with glass in good condition than the collapsible Summicron.

Early collapsible Summicrons do contain thorium, which is significantly radioactive. It would be a bad idea to use one as a loupe held up to your eye, and it wouldn't be the best choice of paperweight to keep permanently on your bedside table, but the risk is low in normal use compared to other sources of radioactivity in the environment (like living in a house with granite walls). Although (as with everything about vintage Leica) there might be exceptions, there are external differences between the thorium and the later design that can be used to distinguish between the lenses, as illustrated here.

Edited November 17, 2022 by Anbaric

[Pyrogallol]

The thorium glass collapsible Summicron lens are more collectible than the ordinary ones and make more money.

[UliWer]

vor 4 Stunden schrieb Tragg:

I am looking for a collapsible Summicron but want to avoid a radioactive lens for the reasons outlines above. Do you have any information that would help me identify one of  these lenses? Was Thorium or Lanthanum used for any lenses besides the Summitar and Summicron?

 

To sum it up:

Lanthanum alone in optical glass will show now risk of radioactivity. The list in #7 is not very helpful as it mixes up glasses with Lanthanum and with Thorium - only the latter will be radioactive. Lanthanum was used for many other lenses with LaK9-glass, which are not in the list, e.g. the old 1:2.8/5cm Elmar - though without radioactivity.

Only the very early collapsible Summicrons may have Thorium, which is radioactive. If you are looking for an LTM-version, and want to avoid any risk for radioactive glass, you might look for one with serial number 1.200.000 or higher - and you are on the very safe side (even much lower numbers have no Thorium, but there are some uncertainties for the numbers around 1.000.000). The "normal" Summitar will neither have Lanthanum or Thorium, so showing no radioactivity at all. Only the very rare "Summitar* - with an asterix behind the name - were prototyes for the Summicron and used Thorium glass. 

If you are looking for a collapsible Summicron with M-mount, you are always safe, that the glass won't have any Thorium - as long as you are sure that it s a real M-mount version, and not an LTM with a fixed adapter. 

Edited November 17, 2022 by UliWer

[Al Brown]

4 hours ago, frame-it said:

which reduces when the lens is exposed to the sun for some time

 

Oh wow, he covered the probe with a red dot 😁

[luigi bertolotti]

There are a lot of collapsible Summicrons that are absolitely sure about radioactive contamination from Th-La : https://wiki.l-camera-forum.com/leica-wiki.en/index.php/Summicron_(I)_f%3D_5_cm_1:2  . thousands of items in batches around 1.200 1.300.xxx  (and , as said above, the "radioactive"  are more costly for collectors interest : I'm very proud to have a LTM 920.382, very yellowish... 😁)

For using, good mechanics (including diaphragm mech) and glass conditions are more important than radioactivity... but is widely reported that "late" items have in general a better coating - a technology that was evolving just in those years - and this is a plus in use : indeed, my Summicron (rigid) 1.986.384 is definitely better (still today an excellent 50 on digital M) than the collapsible above quoted.

 

 

 

Edited November 17, 2022 by luigi bertolotti

[Anbaric]

2 hours ago, Anbaric said:

You don't need to worry about Lanthanum in general, which is still used today and has very low levels of radioactivity. Natural lanthanum contains only a tiny proportion of a long-lived radioisotope. Lots of things we don't bother about also contain small quantities of radioisotopes, like potassium-rich foods (you can detect the radioactivity of a banana with sensitive measuring equipment). The only specific concern here is that some early batches of lanthanum glass may have a degree of thorium contamination, as suggested by Marco Cavina.

The Summitar does not contain thorium, but a small series of what are effectively pre-production collapsible Summicrons (which do contain thorium) were engraved "Summitar *". These are collectable and correspondingly expensive. The regular Summitar is a fine lens, especially if coated, and is usually easier to find with glass in good condition than the collapsible Summicron.

Early collapsible Summicrons do contain thorium, which is significantly radioactive. It would be a bad idea to use one as a loupe held up to your eye, and it wouldn't be the best choice of paperweight to keep permanently on your bedside table, but the risk is low in normal use compared to other sources of radioactivity in the environment (like living in a house with granite walls). Although (as with everything about vintage Leica) there might be exceptions, there are external differences between the thorium and the later design that can be used to distinguish between the lenses, as illustrated here.

Reading that back, I see I didn't make it clear that use of thorium in the earliest Summicrons (and many other lenses from other manufacturers, though Leica themselves did not use it again) was deliberate, a way of giving the glass its desired properties before improved formulas were developed that didn't require it. Supposed contamination of lanthanum glass with thorium, on the other hand, was an incidental issue. It has been claimed that this may have happened at speciality glass factories that had previously worked with thoriated glass. It has also been claimed that the lanthanum may not always have been completely pure to start with (the mineral ore lanthanum is typically refined from, monazite, also contains thorium). I don't know how solid these claims are.

[zeitz]

28 minutes ago, Anbaric said:

It has been claimed that this may have happened at speciality glass factories that had previously worked with thoriated glass.

It is odd that glass sources in Germany, Japan and the US would have the thorium in the glass and then only in a few of their glass products.  I then wonder about how many lanthanum mines there are in the world and if you can identify which mine the lanthanum came from knowing the thorium content.

[Al Brown]

4 hours ago, zeitz said:

It is odd that glass sources in Germany, Japan and the US would have the thorium in the glass and then only in a few of their glass products.  I then wonder about how many lanthanum mines there are in the world and if you can identify which mine the lanthanum came from knowing the thorium content.

What is really mind boggling is the radioactive Fiesta dinnerware from USA - Brilliant red Fiesta is known for having an extra detectable amount of uranium oxide (depleted uranium) in its glaze that produced the orange-red color... made from 1959 until 1973. 

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[Anbaric]

Do not attempt this with a radioactive Summicron.

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Edited November 18, 2022 by Anbaric

[Anbaric]

23 hours ago, zeitz said:

It is odd that glass sources in Germany, Japan and the US would have the thorium in the glass and then only in a few of their glass products.  I then wonder about how many lanthanum mines there are in the world and if you can identify which mine the lanthanum came from knowing the thorium content.

According to Wikipedia, the thorium content of the monazite ore from which lanthanum was extracted varied by source. But of course the degree of any contamination would also depend on how good the refinining process was. And if the claimed contamination was instead from previous use of thorium at the factory, then all bets are off. According to the Google translation of Marco Cavina's article:

'In the light of the above, it is normal for the 1950 Summitar * (star) and the 1951 pre-series Summicron with serial number 92x.xxx to have the classic metamictic yellowing of the lenses and to be slightly active at the dosimeter: for their packaging the original formula by Kleinberg and Zimermann and thorium glass by Chance Brothers; conversely, the very first definitive Summicrons (serial number 993.000 - 1.030.000 approximately) already adopt the final scheme (revised on the computer) with two air-spaced front doublets and the adoption of four LaK9 glass lenses (the same with the Thorium glass of the previous models), however these are "experimental" batches of glass, made in Wetzlar in the glassworks of the House, and the castings were contaminated to varying degrees by small quantities of radioactive oxides.'

I don't know how thoroughly these lenses have been analysed for the supposed contamination - perhaps some lenses with the original thorium formula have simply been confused with later lenses, especially if there is some overlap in the serial number ranges. In any case, you'd expect there would be much less thorium in them than in the lenses where it was used deliberately, like the earliest summicrons (or various Takumars from Japan, or Aero-Ektars from the US). I assume that most lenses known to be radioactive contain thorium by design, not accident.

Edited November 18, 2022 by Anbaric

[Al Brown]

An old joke:

What do you do with photographers who sleep next to their thorium lenses?
Barium.

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Hallo,

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[oldwino]

On 11/17/2022 at 1:01 PM, Al Brown said:

What is really mind boggling is the radioactive Fiesta dinnerware from USA - Brilliant red Fiesta is known for having an extra detectable amount of uranium oxide (depleted uranium) in its glaze that produced the orange-red color... made from 1959 until 1973. 

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Positively Glowing!

[Jerry Attrik]

Anbaric in post #16 said "Do not attempt this with a radioactive Summicron".
I looked at my own radioactive Summicron and thought that statement alone
is an eye-watering caveat!
The brown colouration of the glass imparts a 'warm-glow' to colour negative 
film prints which some find attractive.
Been using the lens for 50 years - no worries mate!

All the best wishes
D. Lox.