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07-14-2015, 04:37 PM   #31
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QuoteOriginally posted by colbycheese Quote
Hello. i am a new member of the forum. I was looking for a takumar 55mm 1.8 lens to buy to use adapted with my mirrorless camera. Anyways after doing a bit of research i learned that the lenses are radioactive. ...
if you want to worry about radiation, consider fukushima...
still pouring 'hot' water into the sea, 4 years on

07-14-2015, 04:39 PM   #32
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QuoteOriginally posted by Transit Quote
if you want to worry about radiation, consider fukushima...
still pouring 'hot' water into the sea, 4 years on
Right ! And that doesn't even make the news anymore. We have been numbed to Truth and Reality !
07-14-2015, 05:39 PM   #33
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Here are a Reuters team that shot too long with the Taks ...


07-14-2015, 05:40 PM - 1 Like   #34
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A very interesting chart about the level of ionising radiation exposure in various place, journeys, occupations and medical procedures:

https://xkcd.com/radiation/

However, according to this short Veritasium science video, filmed while producing a longer documentary on the topic, where various sites around the world are visited, the greatest exposure to ionising radiation occurs to the average smoker: 160,000 μSv/year. (Avg. background radiation exposure, according to the chart, is about 3,650 μSv/year.)



Dan.

07-26-2015, 02:19 PM   #35
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QuoteOriginally posted by dcshooter Quote
Thorium is only mildly radioactive and primarily emits alpha radiation (not gamma radiation)
I noticed wikipedia states that Thorium 232 decays by alpha and sometimes rare beta decay, but then I saw a few youtube videos showing people using geiger counters and picking up gamma rays? Can we conclude there are other radioactive materials in these lenses?
07-26-2015, 03:23 PM   #36
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There's always a silver lining.

Takumar normals are now officially OFF my LBA lists.
07-26-2015, 04:11 PM - 1 Like   #37
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Maybe there is no actual health concerns, but paranoia issue is real. My sister nearly got her Takumar 50mm 1.4 confiscated in an airport. Ultimately security guys let her keep the lens, but they were quite hesitant.
07-26-2015, 06:15 PM   #38
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QuoteOriginally posted by monochrome Quote
It took 50 years for the vision in my right eye to degrade so much that I had to switch to left-eye shooting.
Have you been to an optometrist or ophthalmologist, and if so, do glasses correct the vision or is your vision problem cataract based? I am just curious to know

07-26-2015, 06:40 PM   #39
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It was a tongue-in-cheek reference to the radioactive Takumar normals (affecting my vision). However . . . .

I do have an advanced case of glaucoma. I've had several surgeries to install after-market parts in both eyes (non-OEM) so the progress of the disease is controlled, but not reversible.

I've also had both lenses replaced due to cataracts. As a result, whereas for fifteen years I've had to shoot left-eye with a +2.0 SMC Corrective Lens Adapter (K or M, depending) attached to the viewfinder frame to achieve focus, I can now use the K-3 viewfinder with about +0.5 diopter correction (which corrects for the 'normal' -0.5 VF diopter correction) right eye. What a relief to no longer poke my eye with the film advance lever when metering a KX !!

I just 'adjust' for focus challenges with film cameras.
07-26-2015, 08:02 PM   #40
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QuoteOriginally posted by stillshot2 Quote
Can we conclude there are other radioactive materials in these lenses?
No.

Thorium was added to the glass, probably as an inorganic salt. While thorium emits an alpha particle on decay, there is a accompanying gamma release from its decay product (radium 228) by gamma decay. The EPA and CDC both list alpha and gamma radiation as resulting from thorium 232 decay.

A Geiger counter will detect gamma, but with low efficiency. The Flickr page I linked to on the first page tallied close proximity alpha and gamma with a Geiger counter and at distance (100mm) using a scintillation probe (more sensitive and better for quantitative work).

https://www.flickr.com/photos/s58y/6802092736


Steve

Last edited by stevebrot; 07-26-2015 at 11:31 PM.
07-26-2015, 08:38 PM   #41
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QuoteOriginally posted by stevebrot Quote
The Flickr page I linked to
Hmm, it looks like the takumar 50mm f1.4 is one of the more radioactive lenses, and the takumar 55mm 1.8 is much less.

I just got my first m42 lens from my local pawn shop and am waiting for the m42 adapter to arrive in the mail. Yep, it's a super takumar 50mm 1.4 which set me back $30. I am definitely still going to use it but after seeing all these threads I decided to store my camera gear somewhere else instead of right next to my bed and desk where I spend lots of time.
07-26-2015, 10:10 PM   #42
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QuoteOriginally posted by stillshot2 Quote
Hmm, it looks like the takumar 50mm f1.4 is one of the more radioactive lenses
The ST 50/1.4 is the prototypical radioactive lens against which all others are measured. It is not the highest, but is the one people think of when the words "radioactive lens" come up.

Be aware that the Super-Multi-Coated (S-M-C) and SMC versions are not thoriated.* If you find that the glass in your new lens is yellowed (most are) due to the radiation, there are several remedies that have been shown effective. The safest and easiest for both you and the lens uses an inexpensive desk lamp (JANSJÖ) from IKEA. Google IKEA yellow takumar for comments from all over the Web. Be aware that there are some purists that feel it is wrong, immoral, unethical, etc. to clear these lenses...go figure.

Edit: Fastest Tool to clear yellowed Thorium lenses - Rangefinderforum.com


Steve

* What was I thinking...not true...

Last edited by stevebrot; 07-27-2015 at 12:25 PM.
07-27-2015, 12:17 AM   #43
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QuoteOriginally posted by stevebrot Quote
The ST 50/1.4 is the prototypical radioactive lens against which all others are measured. It is not the highest, but is the one people think of when the words "radioactive lens" come up.

Be aware that the Super-Multi-Coated (S-M-C) and SMC versions are not thoriated.

Steve
I own a handfull of s-m-c and smc takumars, 55/1.8 (and 2.0), and 50/1.4, all radioactive (measured with a radiation meter).
The early super takumar 55/1.8 (and 2.0) appeared not radioactive, but later 55/1.8 super takumars are.
07-27-2015, 04:35 AM   #44
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QuoteOriginally posted by glasbak Quote
I own a handfull of s-m-c and smc takumars, 55/1.8 (and 2.0), and 50/1.4, all radioactive (measured with a radiation meter).
The early super takumar 55/1.8 (and 2.0) appeared not radioactive, but later 55/1.8 super takumars are.
Im curious what detector are you using ? Several of mine are also , but I wonder if its from being in close proximity to the ST 50mm 1.4 ? My carpet that's been here for 19 years is the highest readings but I live 12 miles directly north of the "Gnome Project"site so that accounts for it Im sure. All are negligible amounts and not much higher than background at times.
For the uneducated and uninformed the word "Radiation" and "Fear" go hand in hand. Im a very cautious person and don't believe much anything our Government says is safe. Through my old job at WIPP and self education , more worried about my occupational past exposure and medical exposure (I-131 and I-123) than any Takumar by far.
I repeatedly tell my fellow Pentaxians its nothing to worry about at all...... Yet the Fear Mongering is still rampant. If You want to worry about the REAL Dangers of radiation , there are things You most assuredly DONT want to know about going on in this country that would and should scare the living shit out of You ! Our Takumars aren't one of them !

Last edited by Dlanor Sekao; 07-27-2015 at 04:59 AM.
07-27-2015, 06:57 AM   #45
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QuoteOriginally posted by stevebrot Quote
several remedies
I am going to shoot with it yellow before I try a remedy, how long does it take to revert back? Decades? The lens I bought had 2 UV filters stacked on it, and I'm pretty sure they have never been taken off since the front element is pristine. So basically this lens is as yellow as it gets

---------- Post added 07-27-15 at 08:43 AM ----------

QuoteOriginally posted by monochrome Quote
I do have an advanced case of glaucoma.
QuoteOriginally posted by monochrome Quote
I've also had both lenses replaced due to cataracts.
Since both eyes seem to be affected, your vision conditions don't seem to be related to the takumars. Either way, I was factoring in if it would be worth it to have poor vision 50 years from now, and since I will be in my 80's... well let's just see if this takumar will live up to it's reputation as one of the top ten most popular rated pentaxfourm lenses! (Still waiting on m42 adapter...)

Last edited by stillshot2; 07-27-2015 at 07:44 AM.
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