Question About Minolta Rokkor 55/1.4 and 55/1.7

[FilmOnly]

Can anyone confirm whether or not either the Rokkor MC 58/1.4 or MC 55/1.7 is radioactive? It is not my intent here to debate or discuss the issue of whether a radioactive lens is safe. I just want to find out if either has thorium (or something else radioactive) in its elements.

With regard to the title, I meant "58/1.4," not "55/1.4."

Thanks.

 

[dnjl]

To my knowledge, only the 58mm f/1.2 had thorium elements (and maybe the 50mm f/1.2, I don't know).

 

[dynachrome]

58/1.4, 55/1.7

I have one 55/1.7 and two or three 58/1.4s. There is no color shift in the 55/1.7. My version is the MC Rokkor circa 1972. I don't think it has any radioactive elements. At the second Sunday Camera Show in Wayne, NJ yesterday one of the merchants told me he had a number of 58/1.4 lenes in his car. He also told me that he "cleared" them by taking then with him to a tanning salon. I just looked at one of my 58/1.8 MC Rokkors, 56315XX. It's attached to an SRT 201 and looks perfectly clear both on and off of the camera. I also looked at a 50/1.4 MC Rokkor-X. It's clear too. In purely technical terms the 50/1.4 MC Rokkor-X is a better lens. It's a more modern design and has better coating. The 58 has pleasant bokeh and is quite good when stopped down even a little. It's not as good for flat copy work where you would want a flatter field but you can always get a 50/3.5 Rokkor/MD/Celtic for that.

 

[FilmOnly]

Thanks, dynachrome...I very much appreciate the straightforward, detailed comments. I have the MC Rokkor-X 50/1.4 and MD Rokkor-X 50/1.7, but I have used them little. Once I get my XE-7 back from its CLA, I will have to use them more...much more. I welcome any other remarks you may have.

 

[lightdreamer]

All Minolta 1.2, 1.4, 1.7 and 2 50mm lenses are free of radioactive elements.

My latest version MC Rokkor 1:1.2 58mm and my latest Version MC Rokkor PF 1:1.4 58mm are also free of radioactive elements, but
I cannot tell you wether earlier examples are too. I measured my examples in our physical lab.

BG

 

[Christopher Walrath]

The first generation MC lenses, characterized by the milled metal focusing rings at times had . . .radioactive compounds of thorium and lanthanum 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 . . . (according to The Rokkor Files). This is not mentioned for the second and third generation MC and later MD lenses that are characterized by the more familiar contoured rubber focusing rings.

 

[FilmOnly]

Thanks, folks...

I just picked up a 100/3.5 Tele Rokkor QE. Any comments on this lens? Since it is a slower lens, I figured that is probably not radioactive.

 

[Christopher Walrath]

No prob. And, unfortunately, no comments on the lens as I have never used one. Although, it is hard to go awry of good glass with a Rokkor.

There's nothing like a good piece of glass.