Good morning everyone, and welcome back to my site. Thanks to those who have the patience to follow my posts. A warm welcome to those who are here for the first time.
I return to a topic already discussed previously. ” RADIOACTIVE Vintage Lenses “. Lenses with optics that included some radioactive elements. Mainly THORIUM and LANTHANUM (LINK TO THE ARTICLE).
Intrigued myself, I wanted to delve further into the topic by carrying out a bit of internet research, from sources that I consider reliable. So reason of this post: Radioactive Vintage Lenses Again.
In the period from the 40s to the 80s of the last century, as already written. Several manufacturers of camera optics used radioactive elements and produced radioactive old vintage lenses.
Broadening the topic to other products and other areas, it emerges that it was a fairly consolidated practice to add radioactive elements to some production processes.
In the 1930s, powdered cream (THO-RADIA) were even produced which included RADIO.
Suppositories to improve sexual performance (VITA RADIUM) always with RADIO.
Even a RADIO broadcaster! …which produced radioactive water.
Until a few decades ago, alarm clocks and watches with luminescent hands were then produced. Which used TRITIUM, or once again RADIUM for the watch dials.
Today we consider all this as crazy, dangerous and harmful to health, obviously… But I think our fathers, grandfathers and/or great-grandfathers were probably on the one hand intrigued, on the other probably not aware of the risk linked not only to the use, but even just exposure to these chemical elements.
As a child in the 70s, I received a TIMEX brand watch with a luminescent dial and hands as a gift. And it was a really nice watch for its time, absolutely useful to have the possibility of having hands and hours illuminated by phosphorescence. No one had warned me about the existence of potentially harmful chemicals inside the watch case.
I don’t think even my uncle, who gave it to me, knew about it. Probably not even the shopkeeper was fully aware. The watch was “lit up” without batteries, and this was why it was manufactured and therefore marketed. Certainly no one had asked himself the problem of some infinitesimal part of possible radiation, deriving from the presence of TRITIUM or some other radioactive element.
So it doesn’t surprise me at this point that OPTICAL LENS manufacturers, and not just for photography, have also included elements such as THORIUM in their camera glass. Among other things, LANTHANUM lenses for high myopia are still on the market today. And lenses with rare earths to correct vision depending on the type of other vision defects.
Now I don’t want to go into the merits and specifics, firstly because I don’t have the skills, secondly because this is not the subject of the post.
However, it’s interesting to understand the reason linked to my photographic passion. For which THORIUM was mainly added to camera lenses. The reason is that THORIUM limits light reflections in the lenses. Thorium oxide was added to glass as it made it possible to create lenses with a high refractive index combined with low light dispersion.
Thorium glass was also used in ocular lenses for microscopes. Although in those quantities the thorium produced alpha and beta rays that the skin could easily shield. The same could not be said for the cornea of the eyes which could be damaged. Thorium lenses were produced between the 1940s and 1980s, but have since been banned.
Usually, a Thorium lens has a radioactive emission of 0.01 mrem per hour (millirem). When the maximum dose that an individual can absorb in a year without having any effects on his health is approximately 0.5 rem per year. If for a year we always carried with us, day and night, an objective with a thorium lens. The annual exposure would be only 0.09 rem.
Therefore, referring back to my previous post, and considering the occasional use of a vintage lens with thorium lenses. I do NOT personally believe that these can have any type of harmful effect on the user’s health.
Nonetheless, I would still take some OPERATIONAL precautions
I would not disassemble the lens for any reason. Nor would I attempt to repair it if it was damaged in any way.
I would not bring the lens closer to the eyes for more than a few seconds. If possible I would keep it at a distance of at least 50cm from the eyes
I would ALWAYS keep the lens with its original front and back cap mounted. (Also to avoid exposure to possible light from the lens, which causes yellowing).
I would keep the lens in a closed and protected container, in order to avoid any form of indirect contamination. A neoprene pouch and then a metal box to contain it.
Precautions that as far as I’m concerned I already take with my MINOLTA 58MM F1.4 lens. Even if I’m convinced by its serial number that it DOES NOT contain any radioactive chemical element. But having not tried with a GEIGER counter, it is better not to trust it and maintain appropriate caution.
Among other things. I learn that even the first series of CARL ZEISS JENA “TESSAR“ 50mm F2.8 lenses could contain TORIUM in the lenses. Precisely the ZEBRA series of which I am the lucky owner. I will investigate further compatibly with my always too little time, and if necessary I will inform you.
At this point it seems clear to me why MANY manufacturers added THOROUUM to the production process for their camera lenses. This is the optimization of an industrial process derived from the research and design of individual photographic lenses.
If you are interested, I suggest you do some research of your own which may be better and more complete than what I write.
Thanks for your attention and patience, until the next post.
