Nikon AI Lenses and Radioactivity

logan2z · Nov 6, 2021

I have a handful of Nikon AI lenses and was curious if any of them had Thorium in the glass. I'm not terribly concerned about it from a health perspective as I understand the risk of using such lenses is relatively low, but it would be nice to know. Unfortunately, I don't have access to a Geiger counter. I've taken a look at the glass and don't see any obvious yellowing which I understand is a telltale sign of radioactive lenses, although one of them is a 50/2 AI that I've seen included on a list of radioactive lenses floating around the internet.

Just wondering if anyone has done any of their own tests with a Geiger counter and knows if any of the following lenses is radioactive:

Nikon Nikkor 50mm/f2 AI
Nikon Nikkor 50mm/f1.8 AI
Nikon Nikkor 28mm/f2.8 AI
Nikon Nikkor 105/f2.5 AI

Nitroplait · Nov 6, 2021

Don't think thorium glass was even used for consumer lenses in the late 70's (when they started making Ai lenses).
I also think it was only used in the more complex high end designs - non of your lenses qualify as such.
My late 60's Pentax M42 Takumar 50/1,4 does not use Thorium glass, but the earlier first version did.

benjiboy · Nov 6, 2021

logan2z said:
I have a handful of Nikon AI lenses and was curious if any of them had Thorium in the glass. I'm not terribly concerned about it from a health perspective as I understand the risk of using such lenses is relatively low, but it would be nice to know. Unfortunately, I don't have access to a Geiger counter. I've taken a look at the glass and don't see any obvious yellowing which I understand is a telltale sign of radioactive lenses, although one of them is a 50/2 AI that I've seen included on a list of radioactive lenses floating around the internet.

Just wondering if anyone has done any of their own tests with a Geiger counter and knows if any of the following lenses is radioactive:

Nikon Nikkor 50mm/f2 AI
Nikon Nikkor 50mm/f1.8 AI
Nikon Nikkor 28mm/f2.8 AI
Nikon Nikkor 105/f2.5 AI

logan2z · Nov 6, 2021

Nitroplait said:
Don't think thorium glass was even used for consumer lenses in the late 70's (when they started making Ai lenses).
I also think it was only used in the more complex high end designs - non of your lenses qualify as such.
My late 60's Pentax M42 Takumar 50/1,4 does not use Thorium glass, but the earlier first version did.

I have no idea if this list is accurate, but it does include some AI/AIS lenses:

https://camerapedia.fandom.com/wiki/Radioactive_lenses

FotoD · Nov 6, 2021

logan2z said:
I have no idea if this list is accurate, but it does include some AI/AIS lenses:

https://camerapedia.fandom.com/wiki/Radioactive_lenses

Yes, I only listen to this guy when it comes to science and health matters! (He seems to be the source of the very excellent list you linked to)

OK, he admits he doesn't have a Geiger counter, and he 'forgot' to put units on the measurements. But in my experience, if it's on the internet it has to be very true.

Throw away all your Nikkors now! Or better yet, send them to me.

Nitroplait · Nov 6, 2021

logan2z said:
I have no idea if this list is accurate, but it does include some AI/AIS lenses:

https://camerapedia.fandom.com/wiki/Radioactive_lenses

Yeah the reference in your source to is really convincing. I must revise my position.
Anyway; everything is radioactive to some degree. If you are worried, NEVER set foot on a airplane!

Bronson Dugnutt · Nov 6, 2021

My feeling is that thoriated elements had been phased out by the time the AI standard was introduced, but that is pure speculation on my part.

The two lenses in my possession that required a UV treatment are:

Nikkor-N Auto f1.4 35mm (9-bladed iris, #3672xx indicating mfg in the early 1970's)
SMC Takumar/6x7 f2.4 105mm (#5320xxx again indicating early 1970's mfg)

logan2z · Nov 6, 2021

Nitroplait said:
Yeah the reference in your source...is really convincing. I must revise my position.

That's why I said I wasn't sure how accurate the information was.

Nitroplait said:
If you are worried, NEVER set foot on a airplane!

As I said, I'm not worried. It was more a matter of curiosity. And if I never set foot set foot on an airplane again I'd be thrilled. I hate flying.

RDW · Nov 6, 2021

logan2z said:
I have no idea if this list is accurate, but it does include some AI/AIS lenses:
https://camerapedia.fandom.com/wiki/Radioactive_lenses

FotoD said:
Yes, I only listen to this guy when it comes to science and health matters! (He seems to be the source of the very excellent list you linked to)

Nitroplait said:
Yeah the reference in your source ... is really convincing. I must revise my position.

Angry Photographer and Camerapedia seem to be drawing on this forum post by Francesco Luzzu without understanding it:

https://www.photo4u.it/viewtopic.php?p=1530804&sid=c5ec04985b78ebb71e494ca5efa4220f

It being in Italian is no excuse - Google Translate does a good job:

https://www-photo4u-it.translate.go...auto&_x_tr_tl=en&_x_tr_hl=en-GB&_x_tr_pto=nui

The key point is that the background level is 178 - anything with this reading or close to it isn't significantly radioactive. Most of the lenses listed don't read much above background.

FotoD · Nov 6, 2021

RDW said:
The key point is that the background level is 178

Oh no. Are you saying that the Angry Photographer is wrong?

On a more serious note, I've measured several of my Nikkors and those are absolutely *not* radioactive. Among them a 2.5/105 and a 1.8/50. The older 1.4/35 could very well be radioactive though, but I don't have one so I don't know.

RDW · Nov 6, 2021

FotoD said:
Oh no. Are you saying that the Angry Photographer is wrong?

Perish the thought!

FotoD said:
On a more serious note, I've measured several of my Nikkors and those are absolutely *not* radioactive. Among them a 2.5/105 and a 1.8/50. The older 1.4/35 could very well be radioactive though, but I don't have one so I don't know.

It looks like the older 35/1.4 is:

https://www.reddit.com/r/Nikon/comments/ihkmh3/my_1970_nikkor_35mm_f14_is_slightly_radioactive/

It's suggested elsewhere that this only applies to the pre-AI versions with scalloped metal focus rings, and the lens was reformulated without thorium when they moved to the 'K' version (still pre-AI, but rubber focus ring).

http://www.photosynthesis.co.nz/nikon/lenses.html#35
https://www.destoutz.ch/lens_35mm_f1.4_350004.html
https://www.destoutz.ch/lens_35mm_f1.4_387149.html

reddesert · Nov 6, 2021

RDW said:
Angry Photographer and Camerapedia seem to be drawing on this forum post by Francesco Luzzu without understanding it:

https://www.photo4u.it/viewtopic.php?p=1530804&sid=c5ec04985b78ebb71e494ca5efa4220f

It being in Italian is no excuse - Google Translate does a good job:

https://www-photo4u-it.translate.go...auto&_x_tr_tl=en&_x_tr_hl=en-GB&_x_tr_pto=nui

The key point is that the background level is 178 - anything with this reading or close to it isn't significantly radioactive. Most of the lenses listed don't read much above background.

Thanks for that. I looked at the camerapedia list a while ago and understood that the Nikon-AI section of it, in particular, had to be BS because all of the "activity" numbers were nearly the same. Lens construction differences, element sizes, and so on mean that if the lenses were really radioactive, there should be significant differences in readings. I had to stop the Angry Photographer youtube video after a minute or two. Reading that the numbers came from the Italian forum post and include the background level explains how the myth has propagated.

Here is a discussion of radioactive camera lenses from a reliable source, the Oak Ridge museum of radioactivity: https://www.orau.org/health-physics.../products-containing-thorium/camera-lens.html This isn't an exhaustive list of radioactive lenses, but a factual discussion of the issue.

I could probably get access to a Geiger counter, but it's not clear that I own any well-known radioactive lenses, other than a Kodak Signet that shows no sign of radiation browning. IME, digital detectors can be sensitive to radiation events, so if someone who has a known radioactive lens and a CCD digital camera took say a 30-60 second exposure in a dark room with the lens next to the sensor, they might see an increase in hot pixels (so called "cosmic ray" hits).

Kodachromeguy · Nov 6, 2021

Nitroplait said:
My late 60's Pentax M42 Takumar 50/1,4 does not use Thorium glass, but the earlier first version did.

My 1971-vintage 55mm f/1.8 Super Takumar lens (pre SMC) has some thorium glass. A week under a UV light cleared it. Amazing optical quality for a modest lens.

Bronson Dugnutt · Nov 6, 2021

reddesert said:
IME, digital detectors can be sensitive to radiation events, so if someone who has a known radioactive lens and a CCD digital camera took say a 30-60 second exposure in a dark room with the lens next to the sensor, they might see an increase in hot pixels (so called "cosmic ray" hits).

It's tough to balance the sensor sensitivity required to detect an event and the inherent noise in a long exposure. Too low a sensitivity and particles won't be registered unless lots happen to strike the same photosite. Examining sensor (non?) performance in this way is a fun way to evaluate a digital camera, but ultimately illustrates why film is a better solution for very long exposures.

Here's an extreme crop from a 60s blackout exposure on a V2 w/ Nikkor 35mm f1.4 via FT1. There are a few 'hot' pixels but I don't have any baseline to compare against; the rear element of the lens was the full F flange distance (46.5mm) from a 1" sensor so YMMV.

(RAW and RAW w/ post noise reduction)

Downright... astronomical.

markjwyatt · Nov 6, 2021

logan2z said:
I have no idea if this list is accurate, but it does include some AI/AIS lenses:

https://camerapedia.fandom.com/wiki/Radioactive_lenses

I have

Agfa Color Solinar 2.8/50
Super-Multi-Coated Takumar 55mm f/1.8
Asahi Super Takumar 55mm f/1.8 (need to check S/N)

AgX · Nov 7, 2021

Solinars are of the Tessar type. I know glass sorts employed at Tessar types changed over time. But it is the first time I hear of a such a design incorporating a radioactive glass sort.

Or with other words: So far my understanding was that amongst our range of lenses radiating glass sorts were only employed at lenses of Double-Gauss type at F2 or larger, if at all.

Wallendo · Nov 7, 2021

I don't worry much about "radioactive" lenses. A lens with enough radiation to hurt a photographer would fog the film routinely and not be usable as a lens (at least on lenses with cloth shutters).

AgX · Nov 7, 2021

I am tech guy, but still, holding a Geiger counter near one of my radiating lenses and see the counter suddenly go havoc gives me a nasty feeling.

250swb · Nov 7, 2021

While people will still day-in-day-out get into gas guzzling cars, or fly thousands of air miles, keep turning up the AC, and think 50c temperatures are great for a tan, I think worrying about radioactivity from a Nikon lens is small beer in your survival. I mean, breaking into a cold sweat over you favourite lens may be a relief one day.

markjwyatt · Nov 7, 2021

250swb said:
While people will still day-in-day-out get into gas guzzling cars, or fly thousands of air miles, keep turning up the AC, and think 50c temperatures are great for a tan, I think worrying about radioactivity from a Nikon lens is small beer in your survival. I mean, breaking into a cold sweat over you favourite lens may be a relief one day.

Especially given this is mostly alpha radiation, so pretty much stops at your skin.

AgX · Nov 7, 2021

Then most counters would not even detect that radiation....

Dan Fromm · Nov 7, 2021

AgX said:
Solinars are of the Tessar type. I know glass sorts employed at Tessar types changed over time. But it is the first time I hear of a such a design incorporating a radioactive glass sort.

But there are tessar types and there are tessar types. TTH f/9 process lenses badged Apotal, Cooke Copying Lens, Copying are all tessar types and are all radioactive. I have three, all arrived with tea stained glasses and basking under a UVB bulb cleared all of them.

AgX · Nov 7, 2021

Interesting. Though the Agfa Solinar lenses in contrast were aimed at consumers, even more being in the budget range and I wonder to what extent in price special glass sorts would have been employed here. But I try to check on this.

markjwyatt · Nov 7, 2021

AgX said:
Then most counters would not even detect that radiation....

Thorium 232 produces an alpha particle, but the resulting decay product may produce gamma radiation.

markjwyatt · Nov 7, 2021

AgX said:
Interesting. Though the Agfa Solinar lenses in contrast were aimed at consumers, even more being in the budget range and I wonder to what extent in price special glass sorts would have been employed here. But I try to check on this.

It is listed, but I am not sure it is correct. A lot of Kodak amateur cameras at that time used radioactive lenses.

Nikon AI Lenses and Radioactivity

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