[emeritus]

I inherited a Pentax SLR that has the radioactive f/1,4 50mm Super Takumar lens. Apparently the radioactivity emissions are greater than the present normal allowable limit, but an exception has been made for lenses as there is no substitute for the properties that the radioactive stuff gives to optical glass. Apparently the emission is back towards the film, not forwards, and is insufficient to fog film. On the other hand, the wartime long focus Aero-Ektar f/2.9 , that was often advertised in the photo magazines in the 1960's for use as a cheap telephoto lens, is definitely "hot", and should not be kept under your bed if you want to start a family!

In the late 1950's, my cousin had a South African pen-pal whose father worked in a Uranium mine. She once posted my cousin a matchbox containing some small lumps of crystalline Uranium ore. They resembled irregularly-shaped dirty yellow sugar lumps, and we often used to play with them. I still have the remains of a 100ml bottle of Uranium intensifier that I used to treat under-exposed negatives when I was a schoolboy. I just used to immerse the film in the solution using my fingers. A chemist friend thought it would have been safe enough, as the highly radioactive isotope of Uranium only exists as a very small proportion in the unrefined stuff, and I haven't triggered any alarms in subsequent visits to nuclear power stations.