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Is the Super Takuma 35mm f/2 radioactive?
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PostPosted: Mon Feb 08, 2016 2:00 am    Post subject: Is the Super Takuma 35mm f/2 radioactive? Reply with quote

Been wanting something faster than f/3.5 and f/2.8 in a vintage 35mm.
I just received a copy of this lens that I found for a decent price.
It's in excellent physical condition, with the exception that some previous owner drilled two holes into the face plate in order to be able to unscrew it.
Hence the good price, not for the diehard collecor.

Upon inspecting it, there was a hint of haze, but what stood out was how yellow the lens appeared. Just like some 55mm f/1.8 and f/1.4 models that are yellowed from the Thorium.
Shots with it today in afternoon sunlight were excessively yellow. Unlike my other Super Taks.
I'm not aware of this model being radioactive like their 55s. Is it?

Mine is the 2nd version with the 49mm dia. filter, and 1967->.

Can the Takumar enthusiasts and experts shed some light on this model?


PostPosted: Mon Feb 08, 2016 3:38 am    Post subject: Reply with quote

I have see plenty of Super Takumar 35/2 with 49mm filter become yellowed in eBay. My v1 with 67mm filter does not have this problem.


PostPosted: Mon Feb 08, 2016 4:10 am    Post subject: Reply with quote

Appears the v2 is indeed radioactive. Assumed it would be like the v1.
Hopefully it'll respond favorably to UV treatments.


PostPosted: Tue Apr 12, 2016 2:52 am    Post subject: Reply with quote

I second the 35mm Tak f2 (49mm variants) being radioactive. It seems to take quite a bit longer to clear up too vs the super tak 50 f1.4. Not sure if that is an effect of aperture too.


PostPosted: Tue Apr 12, 2016 5:41 am    Post subject: Reply with quote

FotoPete wrote:
I second the 35mm Tak f2 (49mm variants) being radioactive. It seems to take quite a bit longer to clear up too vs the super tak 50 f1.4. Not sure if that is an effect of aperture too.


I noticed that too. Mine was quite yellowed. I've put it away until a stronger UV source can be obtained to deal with it. It wasn't that good a performer anyway, so it's back to my 35mm f/2.8 lenses.
Wink


Last edited by WNG555 on Tue Apr 12, 2016 10:22 pm; edited 1 time in total


PostPosted: Tue Apr 12, 2016 8:14 am    Post subject: Reply with quote

I've bought a couple over the years. Both were very yellow, but responded to UV light better than 50/1.4.

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PostPosted: Tue Apr 12, 2016 11:12 pm    Post subject: Reply with quote

Is that the same lens as the SMC Takumar 35mm f/2? I have that lens and haven't noticed any yellowing.

And as to the subject of yellowing radioactive lenses, anyone know WHY they yellow? Is it the actual glass or the coatings that yellow? And why does a UV light clear it up? Just wondering.


PostPosted: Wed Apr 13, 2016 2:36 am    Post subject: Reply with quote

It's the glass. The radioactive particles emitted by the decay chain of the Thorium in the glass cause the glass to turn brown.

This is the reason that all the data collected in the colliders at CERN travels over copper cables, not fiber.


PostPosted: Wed Apr 13, 2016 3:03 am    Post subject: Reply with quote

that bit about CERN is interesting.


PostPosted: Wed Apr 13, 2016 5:46 am    Post subject: Reply with quote

John Shriver wrote:
It's the glass. The radioactive particles emitted by the decay chain of the Thorium in the glass cause the glass to turn brown.

This is the reason that all the data collected in the colliders at CERN travels over copper cables, not fiber.


Thanks for answering this. And as already noted the tidbit about data collection at CERN is very interesting!


PostPosted: Wed Apr 13, 2016 5:08 pm    Post subject: Reply with quote

Roka wrote:
Is that the same lens as the SMC Takumar 35mm f/2? I have that lens and haven't noticed any yellowing.

And as to the subject of yellowing radioactive lenses, anyone know WHY they yellow? Is it the actual glass or the coatings that yellow? And why does a UV light clear it up? Just wondering.


There is no SMC Takumar 35mm f/2. 35/2 Takumar must be Super-Takumar or Super-Multi-Coated Takumar (also abbreviated S-M-C, to distinguish from later lenses with "SMC" written on namering rather than "Super-Multi-Coated".


PostPosted: Wed Apr 13, 2016 7:10 pm    Post subject: Reply with quote

visualopsins wrote:
Roka wrote:
Is that the same lens as the SMC Takumar 35mm f/2? I have that lens and haven't noticed any yellowing.

And as to the subject of yellowing radioactive lenses, anyone know WHY they yellow? Is it the actual glass or the coatings that yellow? And why does a UV light clear it up? Just wondering.


There is no SMC Takumar 35mm f/2. 35/2 Takumar must be Super-Takumar or Super-Multi-Coated Takumar (also abbreviated S-M-C, to distinguish from later lenses with "SMC" written on namering rather than "Super-Multi-Coated".


You're right. Mine is labeled "Super-Multi-Coated" making it the "S-M-C" version. Now I need to update my lens list to reflect that. Smile