Carl Zeiss Jena "Zebra"

[connloyalist]

At the risk of opening a can of worms.... I am not making any judgements here one way or another with the following question, just want to know where I stand.

Today I was reading an article (this one: 50mm Lens Comparison – Radioactivity) suggesting that all Carl Zeiss Jena lenses that are radioactive are "zebra" versions, but that not all zebra lenses are radioactive ("all cows are mammals but not all mammals are cows").

Is this correct? In other words, are all Carl Zeiss Jena lenses that are not a "zebra" version not radioactive?

Regards, Christine

 

[Snowonuluru]

I once had a question regarding some zeiss vintage camera / lens combo but didn't know whom to ask. I wrote an email to Zeiss directly and got a very helpful answer! You might like to try that route if you don't get any info from forum members.

 

[kmcsmart]

According to this looks like some non zebras are radioactive.
https://camerapedia.fandom.com/wiki...Radioactive_.28by_the_creator_of_this_page.29

 

[connloyalist]

According to this looks like some non zebras are radioactive.
https://camerapedia.fandom.com/wiki...Radioactive_.28by_the_creator_of_this_page.29

Answering my own question from last year, yes you are correct. I have since acquired a CZJ Flektogon 35mm 2.8 aluminum version (so this is "pre-zebra") and it is slightly radioactive. Background radiation in my living room is about 0.14µSv/hr. I measured this lens at 0.27µSv/hr.

I have arbitrarily placed a cut-off point at 0.20µSv/hr on the lenses I use. So anything 0.20 or higher is labeled "hot" and gets stored away in a safe location. Including this Flektogon.

By the way, does anyone know how I can submit lenses to the webpage listed above?

Regards, C.

 

[kmcsmart]

There is an edit button at the top of the page (right hand side) that let me edit the document. I am not sure what happens after that

So how do you store your radioactive lenses and how are you testing them?

 

[connloyalist]

There is an edit button at the top of the page (right hand side) that let me edit the document. I am not sure what happens after that

So how do you store your radioactive lenses?

I live in an apartment building and have a storage unit on the ground floor. These lenses sit in a box on a shelf there. So nothing fancy. Since radiation drops off with the square of the distance (inverse square law), at the low levels of radiation of these lenses I assume you shouldn't be able to measure much at even a small distance from the lenses. Plus the storage unit is a reinforced concrete box so no issues there. It's not like I have lumps of reactor fuel sitting on a shelf

But once corona is behind us I might take the Flektogon to a shop that buys vintage lenses to see if they will take it off my hands.

Regards, C.

 

[LilSebastian]

You might find this informative about keeping and using radioactive lenses. Simon tests his own copies and determines the level of radioactivity. Three feet away seems to be the safe zone and caps or containers helps even more.