Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,971   Posts: 1,523,550   Online: 780
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 19
  1. #1
    gnashings's Avatar
    Join Date
    Apr 2005
    Location
    Oshawa, Ontario, Canada
    Shooter
    Multi Format
    Posts
    1,376
    Images
    17

    Radioactive lens ?!

    Someone please educate me... what is this all about:

    http://cgi.ebay.ca/ws/eBayISAPI.dll?...523328188&rd=1

    its apparently radioactive...

    Peter.

  2. #2
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,280
    Blog Entries
    1
    Images
    31
    In the 60s and 70s, there were quite a few lenses made which had one or more lens elements containing radioactive glass. In some cases it might have been due to Thorium-contaminated Lanthanum glass, in a few cases it was deliberate usage of Thorium glass.

    Some of those lenses have attained "legendary" status, as the optical performance was miles ahead of anything else available at the time. So after 40 years those lenses are still legendary - and still radioactive.

    SInce then the use of Lanthanum glasses has become a lot more common, but the refining technique has progressed to the point where the lenses are no longer radioactive. There is good reason to believe that most high-performance lenses made today contain one or more Lanthanum-glass elements, but they are not emphasised to the same degree due to the unfortunate association with radioactivity in the minds of many photographers (and lens reviewers).
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3

    Join Date
    Mar 2005
    Shooter
    Multi Format
    Posts
    3,325

  4. #4
    titrisol's Avatar
    Join Date
    Aug 2004
    Location
    Rotterdam
    Shooter
    Multi Format
    Posts
    1,671
    Images
    8
    "radiactive" lenses containe less radiation than your home smoke detector system and probably than your watch.

    Is just a legend given by the use of rare-earth in the fabrication of glass. Those lenses are probably the best ever made
    Mama took my APX away.....

  5. #5

    Join Date
    Dec 2004
    Location
    Milwaukee, Wi
    Shooter
    35mm
    Posts
    3,242
    Where can I buy 35mm Xray film?

  6. #6

    Join Date
    Feb 2004
    Location
    Minnesota Tropics
    Shooter
    Multi Format
    Posts
    735
    You can get approximately 35mm sized 'sheet' film from dental suppliers. It is called 'periapical' film. However, it is very low resolution and regular film is sensitive enough to xrays to suffice.

  7. #7
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,280
    Blog Entries
    1
    Images
    31
    Quote Originally Posted by titrisol
    "radiactive" lenses containe less radiation than your home smoke detector system
    No.
    Quote Originally Posted by titrisol
    and probably than your watch.
    Certainly not - unless your watch was made no later than 1930.

    Quote Originally Posted by titrisol
    Is just a legend given by the use of rare-earth in the fabrication of glass.
    No - the radioactivity is real. Some lenses are more radioactive than others.
    Quote Originally Posted by titrisol
    Those lenses are probably the best ever made
    No - newer lenses with similar but "cleaner" glass are better. QV the Cosina-Voigtländer APO-Lanthar 90mm - blows the competition right away, including the 1970's APO-Lanthar.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #8

    Join Date
    Feb 2004
    Location
    Minnesota Tropics
    Shooter
    Multi Format
    Posts
    735
    Quote Originally Posted by Ole
    [...] There is good reason to believe that most high-performance lenses made today contain one or more Lanthanum-glass elements, but they are not emphasised to the same degree due to the unfortunate association with radioactivity in the minds of many photographers (and lens reviewers).
    Supposedly Zeiss changed the compound formula for the 38mm Biogon in order to comply with new strident pollution control regulations. Do you know if that has anything to do with Lanthanum-glass?

  9. #9
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,280
    Blog Entries
    1
    Images
    31
    I have no idea what changes were made to the Biogon, nor what glasses are and were used in it. There were a great many different additives used in glass, and there are a great many still in use. If anyone is particularly interested, I have heard that the Schott glass catalogue is an amazing source of information!
    I used the APO-Lanthar as an example because I know that my old 150mm is radioactive (checked with Geiger counter), and that the new 90mm's are not. I also know that the optical formula has been changed a little bit, so that the new ones are even better.
    -- Ole Tjugen, Luddite Elitist
    Norway

  10. #10
    Donald Qualls's Avatar
    Join Date
    Jan 2005
    Location
    North Carolina, USA (transplanted from Seattle)
    Shooter
    Multi Format
    Posts
    1,845
    That might just as easily stem from lead- or barium-doped optical glasses that have been around for, in some cases, centuries. There's a lot more lead glass used in optics than lanthanum glass -- IIRC, the crown glass in a common achromat (as in a doublet loupe or telescope objective) is often leaded. And the glass "mud" from grinding and polishing lead glass is an environmental hazard on the same order as arsenic bearing mine tailings or smelter slag (though of much less volume). I've heard Germany now requires mandatory recycling of glass TV and computer display tubes, as well, with the recycling costs included in initial purchase price (the sane way to do this, IMO), but the result is that the up-front cost increase is partly driving the runaway switch to LCD monitors (which are inferior to CRTs in some significant ways, even though they are light, compact, and use a lot less power -- most notably, with their fixed size display elements, they don't handle multi-resolution display usage at all well in my experience).

    Bottom line, lead glass is on the way out, at least in Germany -- and optics isn't the only industry affected.

    Lanthanum glass is likely much less affected, since there's a lot less lanthanum in a given glass than there would be of lead in a corresponding crown, and the higher index and lower dispersion of lanthanum glass allow using less or no lead glass in other parts of the lens.
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin