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GeneralEdit

There are a significant number of lenses produced from the 1940s through the 1970s that are measurably radioactive. Main source of radioactivity is the use of thorium oxide (up to 30% by weight) as a component of the glass used in the lens elements. Thorium oxide has a crystalline structural similar to calcium fluoride (fluorite). Like fluorite, its optical properties of high refractivity and low dispersion allows lens designers to minimize chromatic aberration and use lenses of lower curvature, which are less expensive to produce. Contrary to commonly seen statements to the contrary, lenses containing lanthanum are not appreciably radioactive - lanthanum is only 1/10,000th as radioactive as thorium. Radioactivity in lanthanum containing lenses is due to the intentional inclusion of thorium in the optical glass mix. The presence of thorium can sometimes, depending on the mixture of other elements in the lens, cause moderate to severe browning of the lens elements. Other common misconceptions hold that it is the coatings of these lenses which are radioactive and brown over time, and that the browning occurs in the balsam between cemented elements. It is the glass itself that contains the radioactive ThO2, and the browning therein is caused by the radiation-induced formation of color centers in the glass matrix.

Radiation LevelsEdit

Typical radiation levels can approach 10 mR/hr (100 μSv/h) as measured at the lens element's surface, decreasing substantially with distance; at a distance of 3 ft. (.9 m.) the radiation level is difficult to detect over typical background levels. For reference, a typical chest x-ray consists of about about 10 mR, a round-trip cross country airline flight exposes a passenger to 5 mR, and a full set of dental x-rays exposes the patient to 10 mR to 40mR. A study carried out by the Physics department of Sweden's Royal Institute of Technology estimates that total exposure to a professional photographer using a typical thoriated lens would amount to only 0.2% yearly allowable exposure to the eye and 0.17% to the whole body under the conservative standards of the Swedish Radiation Protection Authority.

Most smaller lenses with thorium elements pose a negligible risk to human health. However, thoriated glass eyepieces are significantly more dangerous. They can give a very large alpha and beta particle dose to the cornea of the eye, potentially causing cataracts and other problems. Normally these particles are stopped by skin, but the surface of the eye can be quickly damaged by them, and at close range, the dose can be very high.

Kodak LensesEdit

By far the most prolific producer of radioactive lenses was Eastman Kodak. From the 1940s through the 1960s, substantial numbers of amateur cameras were produced and sold with thoriated (containing thorium oxide) lenses, including some of the Pony, Signet, and high end Instamatic (e.g. 800 and 814, but not 100 or 124) cameras. In addition, many professional level Ektar lenses from this era contain thorium. Perhaps the most famous radioactive lenses of all were the Kodak Aero-Ektars.

Curiously, in his notable book, A History Of The Photographic Lens, Rudolf Kingslake (head of the Eastman Kodak lens design department 1937-1968), makes only a single passing comment on the possible use of thorium in Kodak lenses.

Lenses with elements made of radioisotope-containing glass Edit

Some lenses of the 1960s, such as early Minolta Rokkor lenses, have elements made of glass formulas which include small traces of radioactive rare-earth elements. Sometimes this accidental radioactivity causes a significant browning of these lens elements. Some users of such lenses reported in camera blogs that they reduced the browning by exposing these lenses to the ultraviolet rays of the sun. The procedure requires several days of sunny weather to have a positive effect.

The effective diminishment of radiation-induced browning by exposure to sunlight has also been reported for some lenses with thorium glass elements, for example for the Nikkor 35mm f/1.4 lens and the Asahi Super Takumar 50mm f/1.4 lens. Several users have also reported that exposure to UV light from artificial sources, including fluorescent bulbs and UV-emitting LEDs is an even more effective method for reducing the appearance of browning.

Tested lenses Edit

Lenses Tested Radioactive (by the creator of this page)Edit

Lenses Tested Radioactive (elsewhere, or by contributors to this page)Edit

  • Argus Cintagon 50mm f/2.8
  • Agfa Color Solinar 2.8/50 (serial S51644): ~70cpm at the front
  • 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 (#15324) Up to 770 cpm at the rear lens. (very early version) http://www.billead.com/canonfl/
  • Canon FL 50/1.8 I (#58233): Up to 450 cpm / 26 µSv/h at the back lens, up to 7 cpm / 0.4 µSv/h behind camera or at the lens barrel. (early version with graphic hyperfocal distance scale) 
  • Canon FL 58/1.2 (#25516, #44528): Up to 180 cpm / 10 µSv/h at the back lens, up to 30 cpm / 1.7 µSv/h behind camera or at the lens barrel. YouTube
  • 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 (Measured at 46532 CPM @ front element; S.S.C non-Aspherical is not radioactive) YouTube
  • Canon (SUPER-CANOMATIC LENS) R 50mm 1:1.8 No.78xxx YouTube
  • Carl Zeiss Jena Pancolar 55mm f1.4 (measured at 2360 nSv/h)
  • 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 ) YouTube
  • Carl Zeiss Jena Flektogon 35mm f2.8 (source?)
  • 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 https://www.youtube.com/watch?v=dKyc4LIIB6c)
  • Enna München Lithagon 1:3.5 35mm (M42) (DCC.de)
  • Focal (Kmart store brand) 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 = non-uniformly segmented focusing ring (measured at 35137 CPM @ back element)
  • Fujica Fujinon 50mm f/1.4 EBC early style = non-uniformly segmented focusing ring YouTube (unspecified EBC or not)
  • Fujica Fujinon 100mm f/2.8 EBC (Arkku at mflenses.com)
  • Fujica Fujinon 400mm f/4.5 EBC (Arkku at mflenses.com)
  • Fujica Fujinon 600mm f/5.6 EBC (Arkku at mflenses.com)
  • GAF Anscomatic 38mm f/2.8 (GAF Anscomatic 726 camera)
  • Industar 61 L/Z MC is NOT radioactive, as the myth says (L is for Lanthanum. Only 0,089 % of total naturally found Lanthanum (La-138) isotope is radioactive, and even it has half-life of 105 billion years).
  • Kodak Aero-Ektars (various models) YouTube
  • 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 YouTube
  • Konica Hexanon 21mm f4 SN 7029XXX, primarily thorium and thorium decay products
  • Leica 50mm f/2 Collapsible Summicron YouTube
  • Leitz Wetzlar Summicron 5cm f2 (M39)
  • Mamiya/Sekor 55mm f/1.4 (m42, chrome+black, flat rear element) (Measured by specialists, 25th april 2014 @ Poissy, France: from 5 to 10 µSV/h by direct touch & 1720 CPM).
  • Mamiya/Sekor SX 55mm f/1.8 6,8 µSV/h https://youtu.be/DZeqOwv00jI?t=4s
  • Minolta MC W. Rokkor-SI 1:2.5 28mm (early variants)
  • Minolta MC Rokkor-PG 1:1.2 58mm (early variants only; SN 2571225 and later should be non-radioactive)
  • Minolta MC Rokkor 1:1.7 85mm (the earliest variant of the MC line) http://www.dg77.net/photo/x500/mc85.htm
  • Mitakon (Zhongyi) 50mm f0.95 Ver I Speedmaster (4 Lanthanum optic elements)
  • Mitakon (Zhongyi) 50mm f0.95 Ver II Dark Knight(1 Lanthanum optic element)
  • Nikkor 35mm f/1.4 (early variant with thorium glass elements)
  • Olympus Zuiko MC Macro 20mm f/3.5 (http://www.flickr.com/photos/s58y/6802092736/)
  • Olympus Zuiko Auto-S 1:1,2/55 mm (first version with thorium glass elements)
  • Olympus Zuiko Auto-S 1:1,4/50 mm (only first version "Silvernose" is Radioactive) YouTube
  • Olympus Zuiko Pen F 1:1.8/38mm (rear element, measured at approx. 7.5µSV/h or 26 µSv/h)  
  • Olympus Zuiko Pen F 1:1.4/40mm (rear element) 
  • Porst Color Reflex MC Auto 1:1.2/55mm (only a specific version? another copy reported as non-radioactive) #000670 - 37µSv/h
  • Rikenon AUTO 55mm f/1.4 (22937 CPM rear element
  • Schneider Repro-Claron (http://www.arnecroell.com/voigtlaender.pdf
  • Schneider 135mm f/3.5 Xenotar (http://www.arnecroell.com/voigtlaender.pdf)
  • SMC Pentax 50mm f/1.4 (original "K line") YouTube 
  • SMC Takumar 20mm f/4.5 (http://www.flickr.com/photos/s58y/6802092736/)
  • SMC Takumar 35mm f/2.0 (Asahi Optical Co.)
  • Super Takumar 35mm f/2.0 (Asahi Optical Co.)
  • SMC Takumar 50mm f/1.4 (Asahi Optical Co.) (both knurled and rubber focus ring grip versions) YouTube 
  • Super Takumar 50mm f/1.4 (only 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 (http://forum.mflenses.com/radioactivity-of-old-manual-lenses-t25714.html
  • Super Takumar 55mm f/1.8 (Asahi Optical Co.)
  • Super-Multi-Coated Takumar 55mm f/1.8 (Asahi Opt. Co.) (rear element, 8-10µSV/h)
  • SMC Takumar 55mm f/1.8 (Asahi Optical Co.) YouTube YouTube (not all)
  • Super Takumar 55mm f/2.0 (Asahi Optical Co.) YouTube
  • SMC Takumar 55mm f/2.0 (Asahi Optical Co.)
  • SMC Takumar 85mm f/1.8 (Asahi Optical Co.)
  • Super Takumar 6x7 105mm f2.4 (Asahi Optical Co.)
  • Steinheil Auto-Quinon 55mm f/1.9 KE mount
  • Tele-Takumar 6.3 300mm (Asahi Optical Co.) http://jbmedia.zenfolio.com/tt300_63/he0cf60f#he0cf60f
  • Topcor RE GN 50/1.4 (Lanthanum glass [source? Lanthanum or Thorium?]) YouTube
  • Topcon UV Topcor 50mm f/2 (Measured at 283nSv/h)
  • Yashinon-DX 28mm f/2.8 (Yashica) (Measured at 210 nSv/h)
  • Yashinon-DS 50mm f/1.4 (Yashica) (Measured at 680 nSv/h)
  • Yashinon-DS 50mm f/1.7 (Yashica) (Measured at 762 nSv/h)
  • Yashinon-DX 50mm f/1.4  (Yashica) (Measured at 1359 nSv/h)
  • Yashinon-DX 50mm f/1.8 (Yashica) YouTube
  • Yashinon-DS-M 50mm f/1.4 (Yashica) (Measured at 572 nSv/h)
  • Yashinon-DS-M 50mm f/1.7 (Yashica) (Measured at 798 nSv/hYouTube
  • Yashinon-DS-M 55mm f/1.2 (Yashica) (Measured at 1056 nSv/h)
  • Yashinon-ML 50mm f/1.7 (Yashica) YouTube (likely only the older design with 'YASHICA LENS ML 50mm 1:1.7 YASHICA MADE IN JAPAN' writings is radioactive.First version is in fact a DS-M 50mm f/1.7)
  • Yashinon 55mm f1.2 (Tomioka) (also branded as Cosinon, Chinon, Tominon, Tomioka or RevuenonMeasured at 981 nSv/h)
  • Ultragon 115mm f/5.5 (measured at 1.5μSv/h : http://www.arnecroell.com/voigtlaender.pdf)
  • Vivitar Series 1 28mm f1.9 
  • Voigtlander 50mm Nokton Prominent
  • Voigtlander 15cm Apo-Lanthar (measured at 16μSv/h : http://www.arnecroell.com/voigtlaender.pdf)
  • Voigtlander 21cm Apo-Lanthar (measured at 27μSv/h : http://www.arnecroell.com/voigtlaender.pdf)
  • Voigtlander 30cm Apo-Lanthar (measured at 35μSv/h : http://www.arnecroell.com/voigtlaender.pdf)
  • Voigtlander Zoomar 36-82mm f2.8 (measured at 3.1 μSv/h, serial 5033439)
  • Wollensak Raptar 28-75mm f2.3 YouTube
  • Zenitar-M 50mm f1.7 (Lanthanum glass)

Lenses Tested non-Radioactive (by contributors to this page) Edit

Vintage lenses that could have been radioactive, but turned out not to be. A bit of good news!

  • Asahi Pentax-M 28mm f3.5 SMC Shift lens (serial 5144203)
  • Asahi Pentax-M 50mm f2 SMC (serial 4286229)
  • Asahi Auto Takumar 55mm f2.2 (serial 641779)
  • Asahi Super Takumar 55mm f/1.8 (Serial 802344)
  • Asahi Super Takumar 135mm f3.5 (serial 3088850)
  • Asahi Super Multi Coated Takumar 135mm f3.5 (serial 4568738)
  • Canon FD 28mm f2.8 S.C. chrome mount ring (serial 233953)
  • Canon 50mm f1.8 Leica Screw Mount, late model, chrome-and-black (serial 256884)
  • Helios 44M 58mm f2.0 (serial 8077187)
  • Helios 44M-4 58mm f2.0 (serial 8990138)
  • Industar 28mm f/2.8
  • Konica Hexanon 135mm f/3.5 (serial 7322086)
  • Petri 55mm f/1.8 CC Auto (serial 691631)
  • Rodenstock XR-Heligon f/0.75 50mm (serial 9723511)
  • Minolta MD Rokkor-X 50mm f/1.4
  • Mitakon Zhongyi 50mm f0.95 II 'Speedmaster' (serial 001525)
  • Zeiss Jena Flektogon Auto 35mm f2.4 (serial 74736)

Links/SourcesEdit

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