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Thread: Radioactive lenses

  1. #1
    Subscriber Member Jorgen Udvang's Avatar
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    Radioactive lenses

    I don't know if it's much to worry about, but it's interesting reading anyway:

    Decades-Old Lenses May Be Radioactive, Especially if They're Made by Kodak

    Radioactive lenses - Camerapedia

    I particularly noticed this one from Camerapedia (bolding by me):
    "The Kodak Instamatic 814 was a coupled coincident rangefinder camera for 126 (Kodapak) film cartridges - one of a large range of Instamatics. It was made by Kodak in the US, between March 1968 and August 1970. A surprisingly heavy camera, it is well constructed and has a superb Ektar 38mm f/2.8 lens. A Tessar design, the lens contains thorium oxide and is, in fact, radioactive (one of many Kodak lenses from the 40's, 50's, and 60's that share this attribute). The shutter has user-selected speeds of 1/60, 1/125, and 1/250 sec. plus bulb. Film advance is via a spring motor drive that is wound by pulling on a long nylon strap that rewinds into the camera's bottom. The CDS photocell light meter is powered by two PX825 mercury cells, and controls the camera's automatic aperture."

    And I always thought photography was such a healthy activity

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    Re: Radioactive lenses

    At RIT, they tested an Aeroektar by placing it on a piece of photographic paper for 8 hour or so. The lens left a circular fogged ring. A hot lens tends to yellow and so you can usually spot them that way--you can bleach out the yellow by placing it in the sunlight. Many Japanese companies made hot lenses, Pentax has a very common 50mm Takumar that is hot. So does Leica. Personally, I really don't like keeping what would be classified today as low-level nuclear waste.

    When I was at Minolta, one of the employees told me of the lack of modern safety procedure at the plant in earlier periods in their history when they would mix and make glass. Radioactive compounds were not the only nasty things found in glass. While none of the companies advertised it, "green" glass started appearing in lenses a relatively short time ago. And while it presented some engineering problems, it is a good thing. When Konica Minolta finally sold their camera division, they needed to clean up the factory site. There was lots of digging and one building was entirely removed.

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    New Member Studio B's Avatar
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    Re: Radioactive lenses

    Quote Originally Posted by Shashin View Post
    When I was at Minolta, one of the employees told me of the lack of modern safety procedure at the plant in earlier periods in their history when they would mix and make glass. Radioactive compounds were not the only nasty things found in glass. While none of the companies advertised it, "green" glass started appearing in lenses a relatively short time ago. And while it presented some engineering problems, it is a good thing. When Konica Minolta finally sold their camera division, they needed to clean up the factory site. There was lots of digging and one building was entirely removed.
    Woh, I can't imagine what was found in order to remove an entire building.

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    Re: Radioactive lenses

    Quote Originally Posted by Jorgen Udvang View Post
    And I always thought photography was such a healthy activity
    Hardly. Earlier, much sought after emulsions from Kodak had real nasty formulations.

    The radioactive glass isn't harmful.

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    Re: Radioactive lenses

    Radioactive glass was used in many types of optics. The first type of optics it was removed from was eyepieces because it was damaging the eyes of the user. This was in the early part of the 20th century.
    Last edited by Shashin; 5th May 2013 at 08:58.

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    Re: Radioactive lenses

    My Pentax Takumar is radioactive.
    I am not a painter, nor an artist. Therefore I can see straight, and that may be my undoing. - Alfred Stieglitz

    Website: http://www.timelessjewishart.com

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    Re: Radioactive lenses

    We are constantly exposed to radioactivity. Exposure is measured in mill-rems.

    A limit of 2,000 mrem per year is recommended by the International Commission on Radiological Protection (ICRP).

    Eyeglasses (containing thorium) 6 - 11 mrem/year

    Gas Lantern Mantle (thorium-232)= 2 mrem/year

    Thorium is used in welding rods at concentrations of 2%. The estimated effective dose equivalent for three welding rods (0.9 g thorium) in a shirt pocket for 2000 hours/year is 8 mrem.


    Cosmic radiation is high-energy gamma radiation that originates in outer space and filters through our atmosphere.

    Sea Level= 26 mrem/year
    Atlanta (1,050 ft)= 31 mrem/year
    Denver (5,300 ft)= 50 mrem/year
    Minneapolis (815 ft)= 30 mrem/year
    Salt Lake (4,000 ft)= 46 mrem/year

    The greates risk for Thorium is ingestion (breathing dust mostly) as Thorium concentrates in bone. Thorium emits alpha radiation. Alpha radiation is low energy and can be stopped by insubstantial things like paper or thin plastic. Thorium's radioactive decay products emit high-energy gamma radiation which is difficult to stop.

    Don't eat lens dust or sleep with your lenses under your pillow.

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    Re: Radioactive lenses

    afaik, it is only in the tig welding process where thorium may be present, in the electrode, not the filler rod, if any. The main concern is in ingesting the dust when grinding the point. FAQ: The use of thoriated tungsten electrodes

    Tig welding is a bit more specialised compared to what your local garage may use. Come to think of it, who does welding in garages, these days?

    Best wishes,

    Ray

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    Re: Radioactive lenses

    In addition, the lantern mantles ("petromax") laced with thoria are history. One has to actively look for old stocks.

    One thing no one seems to mentioned is the nasty, nasty Americium based smoke detectors. Not only radioactive but totally unnatural and highly toxic.

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