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Pentacon info

Discussion in 'Sony Alpha E-Mount Lenses' started by crashcarter, Apr 4, 2015.

  1. crashcarter

    crashcarter New to TalkEmount

    2
    Apr 3, 2015
    Hi, I have a Pentacon 50mm 1.8 I'd like to use on my A6000 does anybody know if this lens has Thorium in it or how I could find out. thanks.
     
  2. slothead

    slothead TalkEmount Top Veteran

    544
    Mar 1, 2015
    Maryland
    Tom
    Interesting question... I don't know the answer, but why do you need (or want) to know if the lens has any thorium in it?
     
  3. unlo

    unlo Sony ******

    Jan 19, 2014
    Ohio
    Matt
    I'm assuming he wants to know for fear of radiation exposure. Sorry I don't have any knowledge of how to know or test the levels. EBay has cheapo Geiger Counters for smartphones if you want to try that out.
     
  4. slothead

    slothead TalkEmount Top Veteran

    544
    Mar 1, 2015
    Maryland
    Tom
    Thanks Matt, but I'm still curious. Why not ask about Plutonium 238? What's special about thorium or its relationship to this lens? (Is the lens Russian? Is Thorium what the spies use to poison each other?) I'm just curious.
     
  5. crashcarter

    crashcarter New to TalkEmount

    2
    Apr 3, 2015
    Thanks Tom and Matt, I am now the owner of a pristine condition Pentacon 50mm 1.8 and have sent for a adapter for my A6000. But in doing so have come across a lot of debate online about Thorium in the glass. If it is of no danger why are people making such a big deal about it?
     
  6. Lurch

    Lurch TalkEmount Regular

    42
    Apr 5, 2015
    Canberra, Australia
    Jason
    Cant comment on the lenses 'safety', but I can tell you that it is an absolutely fantastic lens.
     
  7. slothead

    slothead TalkEmount Top Veteran

    544
    Mar 1, 2015
    Maryland
    Tom
    Crashcarter,
    I apparently know much less about thorium (or radioactive materials) than I realized! I've been researching the subject in the last hour and haven't even touched the tip of the iceberg. What I haven't seen so far in my search is any reference to a connection between thorium and lenses (although there have been references to Fluoride-thorium and I know that fluoride is sometimes used in lens-making so that's probably where the relationship comes from).

    Having said all that, I think that unless you have a strong sensitivity to radiation, I cant imagine that you need to fear trace elements in the glass (and I've read that the Russians are buying up uranium since the Fukushima disaster brought the price down - so their fluoride glass lenses may not be replete with thorium - if you can follow my logic).
     
  8. slothead

    slothead TalkEmount Top Veteran

    544
    Mar 1, 2015
    Maryland
    Tom
    Interesting 'read'. It would have been a little helpful for an English-speaker to proof-read the paper, but regardless it was fairly understandable in most of the text. I'm certainly out of my league in thinking about radiation sources in lenses, but it also sounds like it was much more common years ago. Who knows what the current practices are, but I would hope that as sensitive as manufacturers are nowadays to human safety, they would consider these practices.
     
  9. Kirkp

    Kirkp TalkEmount Regular

    151
    Nov 2, 2014
    I'm no expert, but I researched online after acquiring a Minolta Rokkor 28mm f/2.5 lens. I read that the hazard of Thorium appears to be alpha particles and that alpha particles won't penetrate most materials, including the dead layer of skin. However, thorium is extremely hazardous if ingested. I concluded that I could use my lens as long as I don't don't smash the glass and ingest the dust or hold it up to my eye or other soft tissue for long durations. Some telescope eyepieces had thorium at one time, so eye exposure was a real hazard for astronomers.