Lens Asahi Super-Takamar

[lucien]

Hi I have a m42 super tak 50mm 1.8, the radioactive one no lolz. I read somewhere that you can give it a sun bathe to lower/get rid of the radioactivity. How long do I have to do this and will I lose the nice yellow sheen on the glass?

Thanks,

 

[fredlong]

Thorium, the radioactive element in the glass, has a half life of 14.5 billion years. I've heard of black lights (UV) being used to reduce the yellowing but there's no way to "get rid" of radiation. Just don't hold it up to your eye or rub it on your gonads and you should be fine

 

[Brian]

Is it the 55mm F1.8? I have that one. I also have the 50mm F1.4.

The Pentax 50mm F1.8 is a later lens, will not be radioactive.

 

[lucien]

thx, will do. lolz

 

[Brian]

I use a UV Lamp, NOT UV-C, to cure the yellowing. Sun Bleaching works BUT will make the lens hot and will bake the grease in it.

 

[lucien]

In response to Brian,

It is a Asahi Opt. Co Super-Takumar 55mm1:1.8 Serial: 3661841. That would be great. I don't like to waste time doing this. And after reading about the 1/2 life it's a lost cause anyway

 

[fredlong]

I'm sorry, I got the half life wrong. It's more like 14.05 billion years. Oops

 

[lucien]

Is that all, The Sun will have expired and gobbled up the planet, and I'll still be around.

I just put it back in the sleeve. Lost cause. Thanks though

 

[fredlong]

On a positive note, your lens is only half as radioactive as it was at the time of the big bang!

 

[wt21]

On a positive note, your lens is only half as radioactive as it was at the time of the big bang!

The Big Bang - man, I knew the Pentax lenses were vintage, but I didn’t know they were THAT old. And who would have thought random forces could produce such smooth focus rings!

 

[Brian]

Thorium is an Alpha Emitter. The radioactive elements are internal to the lens- unless you smash the glass and inhale the power, it will not hurt you.

The Radioactive v1 Summicron has Thorium glass in the front element. I keep filters on my pair of them.

 

[lucien]

Will I turn into the incredible Hulk or some version of him? With a camera

 

[Brian]

Alpha Emitter: if you ingest it, will damage your stomach lining. This is something I remember from Physics Lab in 1975.

Some Internet Idiot decided to smash a Pentax 50/1.4 Super-Tak with a big mallet. Huge Dust Ball surrounded him. He obviously new nothing about Physics.

 

[lucien]

Did the said person, succomb to radioactive poisoning? Or are they alive and kicking? Out of curiosity? What was the thinking, putting radioactive stuff in lens anyway? Your knowledge is very extensive

And how is the bokeh and sharpness of said lens? Are there any samples on the forum?

 

[rayvonn]

My advice, and I know this sounds obvious, was that in general terms you’re ok using one as per normal but do not in any circumstances drop one, if it smashes then you’ve got a problem.

 

[lucien]

Aye Aye, why didn't they come with a warning label? It wasn't "in" at the time?

 

[Brian]

Thorium glass has a high index of refraction, and low chromatic dispersion. Radioactivity is slightly above background. Alpha rays are stopped by Paper. It is much less dangerous than Radium used to make Watch Hands glow.

I adapted a Pentax 50/1.4 Super-Tak to Leica M-Mount, will try to find some shots.

The edge-to-edge performance of the 55/1.8 is extremely good based on this 1976 test,

 

[Brian]

Aye Aye, why didn't they come with a warning label? It wasn't "in" at the time?

Air should have a warning label these days. Warning: breathing Air may Kill you. More dangerous than this lens.

 

[lucien]

Thanks, basically it was the norm. And considered safe. And it was the "cutting" edge tech at the time? Am I close? If so I got it. Have to agree with the "air" stuff though esp if you live in China, India

that's the super tak. 55 1.8 m42 screw mount right?

 

[Richard]

Will I turn into the incredible Hulk or some version of him? With a camera

Yes, and your superhero name will be Asahi Super-Takumar!

-R