Sankyo Kohki Komura

Started 11 months ago | Discussions thread
Goethe
OP Goethe Senior Member • Posts: 1,649
Re: Sankyo Kohki Komura

ProfHankD wrote:

Goethe wrote:

iTrax wrote:

lot of old lenses , like Pentax Takumar's , will turn yellow with age , I have many of them,

they will not harm you.

You can remove the tint with UV light.

https://www.youtube.com/watch?v=xjGjgqZjzPM

Thanks. I am familiar with radiation in old lenses, from thorium and lanthanum. I'm not worried about any radiation harming me. Well, other than accumulated doses over time. But radiation has the possibility of harming electronics, up to and including dead pixels in the sensor. Not a given, but it can happen. Which is why I asked if these particular lenses might have thorium, because some appear yellow.

If I remember correctly some Takumars emit far more from the front of the lens. But many old lenses emit heavily to the rear.

They certainly **might** be -- but the glass additives that happened to be mildly radioactive also tended to be not too cheap, so 2nd-teir brands didn't use them much.

Short of testing them with a counter, yellowing that clears with UV exposure would be a good hint that they're radioactive.

BTW, I don't leave known radioactive lenses on cameras for storage, but I think the probability of causing structural damage to the sensor (as opposed to a "soft error" within an exposure) is near zero.

Thanks for this Prof. There is a lot of conflicting information on the web as to what we can actually expect from radioactive lenses. I understand that there are generally no immediate health concerns, but I dont agree that everything is fine and they cant hurt anyone (which I know is not what you said here). As for electronics, I have found arguments on both sides as to why sensors may or may not be affected. It all comes down to a personal choice and while I will never berate someone for their use of radioactive lenses I myself have chosen not to use them anymore. Even though I have a radioactive Mamiya Sekor on a display camera in my living room.

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