"Hot Lens" Takumars..which ones?

[Paul A]

I've read that only the older Auto-Tak (8 element [and not 7 element: Super Tack, S.-M.-C, SMC)] 50/1.4 and the 30/2 are hot but i've seen 55 1/8 being 'tested' and passing (hot hot hot) with glowing colors ).
How do we know what's really what?
I'm interested in a 50 1/4 (and a 300/4). Is there any (M42) version 50/1.4 that is not a Hot lens? I am assuming/hoping that the (M42)300/4 does not come in Hot lens in any version.?.
Thanks,
Paul

[s58y]

Based on 1st hand measurements:

- At least some 7-element 50mm f/1.4 S-M-C Takumars are radioactive.
- At least some 55/1.8 S-M-C Takumars are radioactive
- At least some older 55/1.8 Takumars (zebra version) are not radioactive

I've read that the early 50/1.4 8-element Super-Takumar is not radioactive, and that the 50/1.4 SMC Takumar is radioactive. The radioactive 50/1.4 Takumars are among the more radioactive lenses that I've measured, but I dont have any Medium or large format lenses (Aero Ektars, for example).

Here's a video where someone measures radioactivity (or lack of it) from some assorted Takumars:

http://www.youtube.com/watch?v=DZeqOwv00jI

[luisalegria]

Almost all the Super and S-M-C 50/1.4's (7-element) are, I understand. They suffer from the browning or yellowing, which is caused by radioactivity. The early 8-element Super Takumar is rather rare.

I rather like the idea they are radioactive.

[Pancolart]

[visualopsins]

Welcome Paul A

The previous forum threads are at http://forum.mflenses.com/fs.php?sw=radioactive

[Arkku]

I can confirm that my S-M-C 50mm f/1.4, SMC 50mm f/1.4, S-M-C 55mm f/1.8, and Super 55mm f/2 are all radioactive.

If it really matters to you, I suggest the EBC Fujinon 50mm f/1.4. The EBC version is not radioactive, nor is the new style non-EBC with black aperture ring. (Only the old-style non-EBC with silver-coloured aperture ring is radioactive.)

[Paul A]

i called a local fellow selling some SMC Taks of all sizes(of which i'm interested in the 300 f/4 and the 50 1.4)...i mentioned I had some Konica and he said he did too (but not listed).
He has a 50 1.4 AR.
I imagine the SMC Tak is better bokeh (8 blades vs 6) but how about contrast/color/sharpness?
Also..I have a Hexanon 57mm 1.2 that is a "Hot" lens I'm sure but I can not find thorium/lanthanum info about the Konicas like I can about the Taks.
Is the Hexanon 50 1.4 a nuke too? I know it is a much later lens than the 57 1.2/57 1.4 but still in the days of Thorium, no?
Thanks again,
Paul

[Smoli4]

hehe i just read a whole thread Orio has started in 2007 about radioactive lenses, and he actually said the exact same thing i wondered today about storing lenses in your house.

well when i finished reading that thread i remembered that Today(!) I discovered an old lens shop (when i thought there where only two in my city) and i talked to the owner, so the owner is 80+ years old, he owns that store for about 50 years if not more, and the store is Packed from buttom up with lenses... i cant even imagine how many of those are radioactive.... so yeah.. something to think about.

[JBruja]

After reading this forum I decided to measure the radioactivity of my SMC Tak f1.4 50mm sn 7357201 (m42 mount). The rear element reads 527 McRh averaging 2 samples @ 30sec ea. with the Geiger-Mueller tube approx 3/8" from the glass. The counter housing prevented me from getting any closer. The front element registers about 117 McHr. As reference the background reading is 4 - 7 McRh.
In any case these levels are extremely low. A Coleman lantern mantle will produce a reading of over 350McRh. As far as "hot" lenses these are only luke warm but great performers. I have several other lenses that produce interesting reading also.

[JBruja]

[Paul A]

[quote="JBruja"]

[JBruja]

[quote="Paul A"]

[Paul A]

Thanks Jbruja.
BTW-it must be on the other side of Canada where sheep live a worried life.

[martinsmith99]

My 50/1.4 S-M-C Tak does suffer yellowing which I can clear with UV, but my 55/1.8 S-M-C doesn't suffer at all, so I'm not sure that one is radioactive.

[s58y]

[TLN]

My Super-Takumar is not radioactive. Early and rare 50 1.4 version.

[Arkku]