We’ve been going to the lake in the neighborhood a lot these days. This time I used one of my greatest lenses – an infamous and radioactive Carl Zeiss Jena Pancolar 55mm f/1.4. The one I have is named as “aus Jena” on the front of the lens. Most probably it means a kind of export version. Its radioactivity is caused by some amount of the isotopes of thorium on the rear elements, that improves a light dispersion. I even measured the radiation of my pancolar and it’s approx. 20-25 μSv right in front of the rear glass. Pretty close to a legendary Kodak Aero-Ektar lens. It seems to be totally undetectable when a distance will increase till 1.5-2 meters. For the measurements I used very accurate and double-tubed Soviet radiometer ‘Polaron Pripiat PKC-20.03’. The same they use in Chernobyl :) I hope it is not harmful to my health when I’m using it for about 1 hour from time to time. That’s what I want to believe :)