How radioactive are the Super Takumars?

elliott · 11-15-2012, 07:44 PM

Originally posted by Mgarber

Was it the same kind of black light that one would find in a night club or fun house? I have some friends that run bars, they might have one like that.

Usually those aren't good enough, they emit too much visible light to be efficient. Typically if you can light a room with one it isn't a very good UV light.

Mgarber · 11-16-2012, 10:28 AM

Big news! I wasn't losing light due to yellowing, although some is present. I've discovered that my shutter is slightly too fast. I did extensive tests, and made an animation to time the shutter. The results can be seen here (using my 5D as control) more MSG!

The Pentax 6x7 shutter is slightly too fast. Now, the question is how to fix it.

Lxlxlx · 07-30-2014, 07:42 AM

In any case i really suggest to let your takumar's radioactivity to be tested by a specialist.

i did it for mine and he told me that it was way more "active" than he thought.. On the rear glass it emitted 500 CPM (count per minute) of alpha radiation BUT what was important is that Thorium in his decay emitts also beta and gamma rays.
As everybody knows alpha rays are easily stopped by a paper sheet.. We tried to measure the camera (k1000 so not light cast at all) with caps on, inside my bag.
The radiation (gamma and beta this time) were detected at 1meter and a half!
The expert told me that it was not safe to bring that camera with me an entire day even if not shooting at all.
In addition, after the first 30 years or so, the radioactivity is at his peak and the decay will last milions of years.

i suggest anyone to let their lense to be checked by an expert. Don't trust the net blindly..

Lxlxlx · 07-30-2014, 07:46 AM

Originally posted by jolepp

The nuclei that are prodcued as a result of the alpha decay of thorium are themselves radioactive, they decay further in a number of steps to a stable isotope of lead. Some of the steps in the decay chain produce beta particles.

Still, because the half-life of thorium is very long (= rate of decay low) the resulting activity is low.

In any case i really suggest to let your takumar's radioactivity to be tested by a specialist.

i did it for mine and he told me that it was way more "active" than he thought.. On the rear glass it emitted 500 CPM (count per minute) of alpha radiation BUT what was important is that Thorium in his decay emitts also beta and gamma rays.
As everybody knows alpha rays are easily stopped by a paper sheet.. We tried to measure the camera (k1000 so not light cast at all) with caps on, inside my bag.
The radiation (gamma and beta this time) were detected at 1meter and a half!
The expert told me that it was not safe to bring that camera with me an entire day even if not shooting at all.
In addition, after the first 30 years or so, the radioactivity is at his peak and the decay will last milions of years.

i suggest anyone to let their lense to be checked by an expert. Don't trust the net blindly..

**Pepe Guitarra** · 07-30-2014, 08:40 AM

Can you remind us what lenses are radioactive?

**boriscleto** · 07-30-2014, 08:48 AM

Originally posted by Pepe Guitarra

Can you remind us what lenses are radioactive?

The 7-element Super/Super-Multi-Coated/SMC Takumar 50mm F1.4 & the Super/Super-Multi-Coated/SMC Takumar 35mm F2 (49mm filter).

At least 1 of the 6x7 Takumars.

There are also claims that the Takumar 55mm F1.8 & F2 are thoriated as well as the Macro Takumar F4, SMC 85mm F1.8, and SMC Taukumar 20mm F4.5. But these are YouTube claims.

Introduction of Thorium Oxide into Super Takumar Lenses

Radioactive lenses - Camerapedia

CRM-114 · 07-31-2014, 01:44 AM

Awwh come on peeps,

radiation badges are made of what?
(hint, they often called 'film dosimeter')

These are lenses intended for film cameras ;-)

tim60 · 07-31-2014, 01:52 AM

Another way to look at it - if there is radiation it is the result of the thorium turning into something else. The result would be that the glass would have other elements present and the low dispersion property of the thorium glass would not be there. Obviously for the lens to be useful the decay must be slow enough thyat it remains what it was made to be. If that is the case, the rate of decay must be slow, which means it is safe to use.

Lxlxlx · 07-31-2014, 06:30 AM

Even if slow in decay, my lense (don't know how "hot" others are) is still producing ionizing gamma and beta radiation in 1 mt and a half range.. and personally i don't feel really safe being in touch with it for long time.

This type of radiation could (with cumlative exposure) break my DNA strands and cause some desease like cancer.. it depends of course on the amount of exposure but also on how my body reacts to this ionizing rays (this is the part that cannot be sure, everybody is different)

As i told you before it's still better to let an expert check and measure your Taks to know how "hot" is your particular glass. It's really a pity since Takumars are pretty good lenses..

**jbondo** · 07-31-2014, 07:55 AM

I can personally vouch a little-known fact: The Tele-tak 6.3/300 has a single thoriated element. Tele-Takumar 300mm F6.3 Reviews - M42 Screwmount Telephoto Primes - Pentax Lens Reviews & Lens Database
It's buried in the middle of the lens, so it's only obvious when you rebuild it. I think there is another as well. I'll make another post after I check my records...

stevebrot · 07-31-2014, 08:00 AM - **1 Like**

Originally posted by Lxlxlx

personally i don't feel really safe being in touch with it for long time...

That is easy. Don't be in contact for a long time.

Did anyone notice that this is a ZOMBIE THREAD and that all of these things were discussed ad nauseum two years ago?

Steve

klaatu3 · 07-31-2014, 08:19 AM

Originally posted by Lxlxlx

Even if slow in decay, my lense (don't know how "hot" others are) is still producing ionizing gamma and beta radiation in 1 mt and a half range.. and personally i don't feel really safe being in touch with it for long time...

I'm no nuclear scientist, but of all the hazards in the world today, this is the least of your worries. We're more likely to die stepping in front of a moving vehicle while taking tourist photos.

**boriscleto** · 07-31-2014, 08:30 AM - **1 Like**

**Pepe Guitarra** · 07-31-2014, 11:15 AM

In th early days of my career, I worked with radioactive isotopos in tracers to measure and create groundwater models. Other than the eye I developed in the back of my head, no other effect has showed up.

Parallax · 07-31-2014, 11:28 AM

Originally posted by stevebrot

That is easy. Don't be in contact for a long time.

Did anyone notice that this is a ZOMBIE THREAD and that all of these things were discussed ad nauseum two years ago?

Steve

It's also just a bit coincidental that we had 2 people, on the same day, join and post about the dangers of those dreaded Takumars. (The other was banned as a spammer)

07-30-2014, 08:48 AM	#66
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475	Originally posted by Pepe Guitarra Can you remind us what lenses are radioactive? The 7-element Super/Super-Multi-Coated/SMC Takumar 50mm F1.4 & the Super/Super-Multi-Coated/SMC Takumar 35mm F2 (49mm filter). At least 1 of the 6x7 Takumars. There are also claims that the Takumar 55mm F1.8 & F2 are thoriated as well as the Macro Takumar F4, SMC 85mm F1.8, and SMC Taukumar 20mm F4.5. But these are YouTube claims. Introduction of Thorium Oxide into Super Takumar Lenses Radioactive lenses - Camerapedia Last edited by boriscleto; 07-30-2014 at 08:58 AM.

07-31-2014, 06:30 AM	#69
Lxlxlx Junior Member Join Date: Jul 2014 Posts: 39	Danger Even if slow in decay, my lense (don't know how "hot" others are) is still producing ionizing gamma and beta radiation in 1 mt and a half range.. and personally i don't feel really safe being in touch with it for long time. This type of radiation could (with cumlative exposure) break my DNA strands and cause some desease like cancer.. it depends of course on the amount of exposure but also on how my body reacts to this ionizing rays (this is the part that cannot be sure, everybody is different) As i told you before it's still better to let an expert check and measure your Taks to know how "hot" is your particular glass. It's really a pity since Takumars are pretty good lenses..

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11-15-2012, 07:44 PM	#61
elliott Inactive Account Join Date: Dec 2008 Location: North Carolina Photos: Albums Posts: 1,720	Originally posted by Mgarber Was it the same kind of black light that one would find in a night club or fun house? I have some friends that run bars, they might have one like that. Usually those aren't good enough, they emit too much visible light to be efficient. Typically if you can light a room with one it isn't a very good UV light.

11-16-2012, 10:28 AM	#62
Mgarber New Member Join Date: Nov 2012 Location: Taipei Posts: 24	Big news! I wasn't losing light due to yellowing, although some is present. I've discovered that my shutter is slightly too fast. I did extensive tests, and made an animation to time the shutter. The results can be seen here (using my 5D as control) more MSG! The Pentax 6x7 shutter is slightly too fast. Now, the question is how to fix it.

07-30-2014, 07:42 AM	#63
Lxlxlx Junior Member Join Date: Jul 2014 Posts: 39	In any case i really suggest to let your takumar's radioactivity to be tested by a specialist. i did it for mine and he told me that it was way more "active" than he thought.. On the rear glass it emitted 500 CPM (count per minute) of alpha radiation BUT what was important is that Thorium in his decay emitts also beta and gamma rays. As everybody knows alpha rays are easily stopped by a paper sheet.. We tried to measure the camera (k1000 so not light cast at all) with caps on, inside my bag. The radiation (gamma and beta this time) were detected at 1meter and a half! The expert told me that it was not safe to bring that camera with me an entire day even if not shooting at all. In addition, after the first 30 years or so, the radioactivity is at his peak and the decay will last milions of years. i suggest anyone to let their lense to be checked by an expert. Don't trust the net blindly..

07-30-2014, 07:46 AM	#64
Lxlxlx Junior Member Join Date: Jul 2014 Posts: 39	Originally posted by jolepp The nuclei that are prodcued as a result of the alpha decay of thorium are themselves radioactive, they decay further in a number of steps to a stable isotope of lead. Some of the steps in the decay chain produce beta particles. Still, because the half-life of thorium is very long (= rate of decay low) the resulting activity is low. In any case i really suggest to let your takumar's radioactivity to be tested by a specialist. i did it for mine and he told me that it was way more "active" than he thought.. On the rear glass it emitted 500 CPM (count per minute) of alpha radiation BUT what was important is that Thorium in his decay emitts also beta and gamma rays. As everybody knows alpha rays are easily stopped by a paper sheet.. We tried to measure the camera (k1000 so not light cast at all) with caps on, inside my bag. The radiation (gamma and beta this time) were detected at 1meter and a half! The expert told me that it was not safe to bring that camera with me an entire day even if not shooting at all. In addition, after the first 30 years or so, the radioactivity is at his peak and the decay will last milions of years. i suggest anyone to let their lense to be checked by an expert. Don't trust the net blindly..

07-30-2014, 08:40 AM	#65
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223	Can you remind us what lenses are radioactive?

07-31-2014, 01:44 AM	#67
CRM-114 New Member Join Date: Feb 2011 Location: Adelaide Posts: 9	Awwh come on peeps, radiation badges are made of what? (hint, they often called 'film dosimeter') These are lenses intended for film cameras ;-)

07-31-2014, 01:52 AM	#68
tim60 Pentaxian Join Date: Apr 2011 Photos: Albums Posts: 8,742	Another way to look at it - if there is radiation it is the result of the thorium turning into something else. The result would be that the glass would have other elements present and the low dispersion property of the thorium glass would not be there. Obviously for the lens to be useful the decay must be slow enough thyat it remains what it was made to be. If that is the case, the rate of decay must be slow, which means it is safe to use.

07-31-2014, 07:55 AM	#70
jbondo Loyal Site Supportaxian Join Date: Sep 2013 Location: Texas Photos: Albums Posts: 503	I can personally vouch a little-known fact: The Tele-tak 6.3/300 has a single thoriated element. Tele-Takumar 300mm F6.3 Reviews - M42 Screwmount Telephoto Primes - Pentax Lens Reviews & Lens Database It's buried in the middle of the lens, so it's only obvious when you rebuild it. I think there is another as well. I'll make another post after I check my records...

07-31-2014, 08:00 AM - 1 Like	#71
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Lxlxlx personally i don't feel really safe being in touch with it for long time... That is easy. Don't be in contact for a long time. Did anyone notice that this is a ZOMBIE THREAD and that all of these things were discussed ad nauseum two years ago? Steve

07-31-2014, 08:19 AM	#72
klaatu3 Forum Member Join Date: Jan 2008 Location: San Antonio, Texas Photos: Gallery \| Albums Posts: 78	Originally posted by Lxlxlx Even if slow in decay, my lense (don't know how "hot" others are) is still producing ionizing gamma and beta radiation in 1 mt and a half range.. and personally i don't feel really safe being in touch with it for long time... I'm no nuclear scientist, but of all the hazards in the world today, this is the least of your worries. We're more likely to die stepping in front of a moving vehicle while taking tourist photos.

07-31-2014, 08:30 AM - 1 Like	#73
boriscleto Loyal Site Supporter Join Date: Dec 2009 Location: North Syracuse, NY Photos: Gallery Posts: 16,475

07-31-2014, 11:15 AM	#74
Pepe Guitarra Site Supporter Join Date: Nov 2010 Location: California Photos: Gallery \| Albums Posts: 2,223	In th early days of my career, I worked with radioactive isotopos in tracers to measure and create groundwater models. Other than the eye I developed in the back of my head, no other effect has showed up.

07-31-2014, 11:28 AM	#75
Parallax Senior Moderator Loyal Site Supporter Join Date: Apr 2008 Location: South Dakota Photos: Gallery Posts: 19,332	Originally posted by stevebrot That is easy. Don't be in contact for a long time. Did anyone notice that this is a ZOMBIE THREAD and that all of these things were discussed ad nauseum two years ago? Steve It's also just a bit coincidental that we had 2 people, on the same day, join and post about the dangers of those dreaded Takumars. (The other was banned as a spammer)