[stevebrot]

The good news is that it is alpha radiation which is stopped by as little as paper.

The additive was thorium oxide, not lanthanum and the radiation is mixed alpha/gamma due to participation by daughter products. There are a couple of fairly comprehensive lists on the web that quantitate the gamma emission (using a scintillation detector) from both front and back. Probably the most widely shared is:

https://www.flickr.com/photos/s58y/6802092736

The radiation is probably not a health risk, but is intense enough to modify the crystal matrix of the glass to cause yellowing over time. This topic has been discussed extensively both on this site and on the Web and a little Google work will result in enough references for a full afternoon's light reading.


Steve

[DonThomaso]

I DO SEE RADIATION IN THESE SHOTS WHY UR DOING THIS TO ME AHHHH MY EYES WHAT HAV U DONE!!!111ONE

P.S.
DT,
There are different types of radioactivity like alpha-radiation, gamma-radiation and so forth. I'm not sure what that sensor is sensitive to and I'm kinda lazy to lurk around for its specs, just adding 2c to your very intriguing and interesting post. And since your measurement setup is quite sensitive to its own design and layout, it would be very nice should you have added measurements for some well-known nukes like bananas, coal, granite or nuts so we could have the base-line to compare the lens radiation to.

Thanks,
Zig

The sensor I have is stated to be gamma-sensitive (as stated in my original post). It is not as refined as other that has come up in this thread, but I think that the same lenses has come up in all tests. I will try to add more at a later stage

[Auzzie-Phoenix]

You should join the radioactive lens club, we could always use more people posting.