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| p.1 #5 · p.1 #5 · 50mm 1.4 super takumar -- reference for performance |
There's a takumar thread here. Have a look: http://www.fredmiranda.com/forum/topic/910305
Also the radio active thing was a process patented to Minolta AFAIK, and I think only some older ROKKORs incorporate such materials. The latest quote I read went like this:
"Early MC ROKKOR 1966-1972 (mc 1st generation):
The quality of the coatings on these lenses is as a general rule not as good as those on later MC and MD lenses, and in some cases radioactive compounds of thorium and lanthanum were added to the glass mixture to increase the refractive index. This is apparent in some of the faster lenses such as the 58mm f/1.2 and 85mm f/1.7, where some early versions that included this glass have had their radioactive ingredients progressively decay, discolouring the glass, and giving the images taken with the affected lenses a very warm cast.
The coating materials on these early MC lenses comprised magnesium fluoride, plus “other ingredients”, and the actual coatings were double coated in a process Minolta called “Achromatic Coating”, giving superior colour rendition and light transmission when compared to competing manufacturers. While not as effective as the newer coatings progressively introduced on later lenses, they nonetheless perform very well, and should not be dismissed from consideration when selecting lenses for use.
In many cases the 1st Generation MC lenses now represent excellent value for money, and as the lens coatings were progressively improved as the years progressed, many of the later lenses of this series may have the same coatings as the later MC models. Certainly the optical formula of many of these lenses was unchanged in the late MC versions and even the early MD versions. Accordingly, it is possible to make considerable savings on some expensive lenses through a willingness to consider these early MC Series lenses as an alternative."