Are thorium camera lenses safe?
Most smaller lenses with thorium elements pose a negligible risk to human health. However, thoriated glass eyepieces are significantly more dangerous. They can give a very large alpha and beta particle dose to the cornea of the eye, potentially causing cataracts and other problems.
Why is thorium used in lenses?
Since this reduces the necessary curvature of the glass, the lens can be made thinner and lighter. Unfortunately, glass with a high refractive index can also have a high dispersion. By adding thorium to the glass, a high refractive index (over 1.6) can be achieved while maintaining a low dispersion.
Which FD lens has thorium?
The only lens I have ever heard of in the Canon FD line up with the Thorium element is the first four versions of the 35mm f2. 0. The first chrome nose versions are always Thorium and those later marked S.S.C. with the concave front element are also Thorium.
When did Nikon stop using thorium?
Yellowing only occurs in the most extreme cases. Some lenses known to contain thorium oxide in the glass do not emit enough radiation to become yellow, but it’s still more than background level radiation. Apparently, the use of thorium oxide was abandoned by Japanese SLR lens makers by the mid-1970’s.
Are old camera lenses radioactive?
If you use vintage lenses, you might have heard that some of them are radioactive. As a matter of fact, many lenses produced between the 1940s and the 1970s emit a measurable amount of radioactivity. It comes from the element named Thorium, which was used in the glass elements of the lenses.
Do old cameras have radiation?
Radioactivity in old camera lenses is due mostly to the widespread use of thorium glass elements in the 1940s, ’50s, ’60s and ’70s. The real threat comes from thorium eye pieces, which are much more rare but would be very close to a very sensitive area.
Which Canon lenses are radioactive?
Like a number of other contemporary lenses, the Canon FD 55mm ƒ/1.2 AL incorporated thoriated glass, a kind of optical glass that is doped with thorium dioxide. The inclusion of this compound makes the glass radioactive.
How can you tell if a lens is radioactive?
But first, how do you know if your lens contains Thorium? If you can see yellowish tint on the glass, this means your lens contains this element. Thorium was used to improve the image quality, but the downside is that it becomes yellowish with time. And, well, that it’s radioactive.
Is Helios 44m radioactive?
This lens is not radioactive.
Are old cameras radioactive?
What is thorium dioxide used for?
Thorium Dioxide is a heavy, white, crystalline (sand-like) powder. It is used in ceramics, in nuclear fuels, as a catalyst, and in electrodes for arc welding.
When did they start using thorium in lenses?
Other manufacturers like Canon, Konica, Asahi Pentax, and others also used thorium in their lenses made between about 1945 and 1980. Manufacturers mostly used thoriated glass for the fastest, more expensive lenses, such as the f1.2s and f1.4s, but slower radioactive lenses also exist.
Are there any cameras that contain thorium oxide?
From the 1940s through the 1960s, substantial numbers of amateur cameras were produced and sold with thoriated (containing thorium oxide) lenses, including some of the Pony, Signet, and high end Instamatic (e.g. 800 and 814, but not 100 or 124) cameras. In addition, many professional level Ektar lenses from this era contain thorium.
Is it safe to use thorium doped telescope lenses?
Normal background radiation exposure for people has been estimated at 620 mrem per year by the NRC. However, if you are concerned about the use of these lenses; don’t use them. NOTE: Thorium doped telescope eyepieces contain high levels of thorium (25%) and will cause damage to the cornea.
Which is more radioactive lanthanum or Thorium lenses?
Despite statements to the contrary, lenses containing lanthanum are not appreciably radioactive – lanthanum is only 1/10,000th as radioactive as thorium. Radioactivity in lanthanum containing lenses is due to the intentional inclusion of thorium in the optical glass mix.