Well, well, well My M42 SMC Takumar really is radioactive | negeriku.info Photography Forums
I'm aware of the radioactivity issue with some Takumars. serial number of the lens (presumably serial number relates to production date?) . Super Takumar 50/ (V2, 7 elements, oval lettering, SN greater than Feb 22, The first version of the Super Takumar 50mm F had 8 lens elements. Lens Review Date: May 20, , I can recommend this lens: Yes | Price: $ I' ve a lot of mms lenses: ST 50/, SMCT 55/, ST 55/, ST 50/ .. Later Pentax changed the optical formula to the 7 element (radioactive one) to . So it sure looks like my copy of the 50mm f SMC in M42 does use . I'm curious as to how much additional radioactivity the thorium decay products, e.g., The Takumar yellowing faded significantly with UV exposure.
I mainly use it on my K10D which has got a split focusing screen and sometime on film bodies. The Super Takumar I bought because I couldn't get it off my mind after seeing how amazing a normal 7-element Super Takumar was rendering.
Takumar radioactivity and serial numbers
I lived with this idea for about 6 months or so and about 2 months ago I spotted a pristine 8-element copy online. But a thing to remember is that my lens came basically mint optically - I can't see even dust inside, no scratches no marks, and with little usage marks to the body.Radioactive Pentax and Takumar Lenses
Also they are quite rare in the UK and I consider this to be a fine investment - a lens from !! That is definitely something!
Well, well, well... My M42 SMC Takumar really is radioactive
First thing that surprised me was a huge inconsistency in metering with my K10D - basically I had to memorize how to compensate in AV mode to get the shot right. The lens handless beautifully - focusing is butter smooth, all the switches and aperture are snappy and generally this is a lens that is simple SUPERIOR to any other lens I have. Even German lenses Zeiss Flektogon - that I have, and Pancolar 50mm - that I handled briefly cannot come close to the build quality and smoothness of operation the Takumar!
Image quality is simple out-stand-ding! Right from wide open in low light - especially loves the 'golden hour' - it simple delivers shapr and contrasty photos! The focusing is simply, images just snap into the focus - especially visible on film cameras with good focusing screen. But I love how K handles and delivers with this lens.
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I am mainly using it in AV mode, focus quickly in loupe mode with X2 or X6 magnification and it never stops amazing me how beautiful shots this lens delivers. Bokeh in typical portrait situations is so smooth and creamy even stopped down to around F2 or F2. I'll give you the synopsis: Unfortunately such glass also has a high light-dispersion rate which makes colours blur. To reduce the light dispersion of lens-glass with an otherwise high refractive index, thorium can be used, either as a dosage within the mix that makes up the glass, or on the coating of the glass elements.
takumar /50 radioactive yellowing: Pentax SLR Talk Forum: Digital Photography Review
Radioactively decayed by-products of Thorium can also exhibit different types of radioactivity, but due to the nature of Thorium radiation alpha, long half-life the average effect on the human body over time due to the other radioactive products in the Thorium cycle is minimal. The naturally occurring Thorium has a half-life three times the current age of the Earth.
There are no stable isotopes. The original patent for using Thorium in camera-lenses is from Before that decade, they did not have much use for it, except in certain types of gas-lamps.
Radioactivity on Takumar 50mm 1.4
Currently, Thorium is considered a more practical but less energetic alternative for Uranium in nuclear power generation. The percentage of Thorium used in camera lens glass or coatings varies between 12 and 28 mass-percent.
It was used in this way in the 's and 's, after which companies stopped doing this since less radioactive alternatives such as lanthanium became available, making the use of radioactive material in lens-production unjustifyable any longer.
It is sometimes still used in medical equipment.