Radioactive LTM Summicron Fogging Question

Is there a danger of film fogging if I leave a LTM coll summicron

(radioactive) mounted on my camera?

 

Anyone know how long it would take?

Probably at least a century! I carry my screw mount Leica IIIf with the Summicron in my pocket regularly with no problems. Of course I haven't had any more children.

Serching I found this

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=0084PL

 

"Harry Geron , apr 24, 2004; 12:34 p.m.

I wish people wouldn?t use that ?radioactive? handle so freely in regard to the early Summicrons. It?s true that some of them (under #1,000,xxx0 used glass (Thorium Oxide) in three elements that was mildly radioactive, but even at it s strongest emission, was less than 2.7 Mr/hr. . .?(The Early Summicron 50/2.0 Lenses by Bill Gordon?,LHSA Viefinder, volume 29 number 3.).

? At this point, the author must stress the fact that these lenses emit radiation at a very low level. The highest lever of radiation is measured at the front element, and the lowest level at the rear element. The level of radiation at the rear of the lens is so low, that it will not fog ASA 400 film, even after four weeks of constant exposure!? . . .

 

It is suggested that anyone interested in this matter familiarize him(her)self with this article.

 

I would certainly not wish to underplay the importance of this situation, but to employ the adjective ?radioactive? to a whole series of lenses without identifying the ones known as such further complicates the understanding of these ?peculiar? lenses."

fwiw, I am most certain that mine is a thorium glass summicron.

 

It had the yellow glass (cleared under strong UV source) and I borrowed a friend's geiger counter.

Test it yourself, pop in a roll of the fastest film you can get and 'expose' for 1, 2 4, 8... seconds (just wind on after the exposure, cap on) and get it developed. My prediction, bugger all effect.

I want me a radioactive summicron just so I can leave it on my desk as a conversation piece ... :-)

Oh, and let us all know the results.

I'm off to buy a roll 800 speed film or so.

 

I need to finish up the current roll in the camera first though.

 

Nice day for a walk!

How will a series of exposures be meaningful? Won't any radiation constantly penetrate the cloth shutter material?

The blank frames should show any base fogging from the lens itself.

My two collapsible 'Crons have serial numbers above 1.3 million. I guess, they are not "radioactive"?

I have a Thorium element Canon 35mm f2.0 Chrome nose and have had it on a camera body with film in it for as long a a couple of months and no sign of any problem. I have kept mine amber to enhance i's B&W contrast and I love the effects. Now as to why I have not used a camera for this lone when you have 16 Canon Fd mount bodies sometimes you foraget which one is next on the play list >

I would think just leaving the camera alone for a week, month, or year would show any fogging. Unless you go through a roll of film every 15 minutes or so I'd think you would be more interested in the fogging between photo sessions.

Actually, I was worried about storing the camera with film in it, but after reading the stuff posted, I'm not worrying about it so much.

Is this behind the legendary Leica glow???

Old Coleman un burnt mantles from the 1970's are radioactive; weird pottery/glazes can be too. Old neon bulbs in 1960's Fluke differential volt meters were radioactive; these lamps are in the chopper feedback circuit. Most replacements bulbs are not radioactive; and they dont last as long in the circuit. The paved streets in a couple of Colorado town are radioactive. .

According to a decent geiger-counter, so is your watch. If you are so worried, I would watch your TV from the neighbor's window.

Which pocket do you carry the lens in?

A geiger-counter showed none of the watches were radiaoactive; even the glow in the dark newer ones. The ancient radiaum watches were radioacative. A couple of foreign non USA mystery coffee cups with wild glaze are radioactive here; plus some old coleman mantels; plus the old aero ektars; and a few kodak printing ektars. None of the russian lenses; even the L/D ones I have are radioactive. The smoke detectors have a trace of radioactive material in them here; plus some old neon NE2 doped variants.

My yellow glass Summicron is one of the first batch #921654. I keep it (when not in use) on a IIIf RDST in one of those old lead lined bags (now useless) they used to sell to protect film from xrays.

 

Just playing it safe. I would sell it if I were really worried...

 

I used to have a SM 5cm cron over 1.3 million sn, definitely not yellow glass.

I have one of these. What is the best way to zap the yellow out of it? I'm in the UK so leaving out in the sun isnt an options since we never get sun... Or should I just leave the yellow?

I left mine under a strong UV black light for a few weeks and it cleared right up.

Leave the most radioactive part on top of a piece of B&W sheet film for a week in the dark and develop it. If you don't see any density, the shielding from the glass/metal/cloth and especially the distance to the film plane will give you 100's of times lower fog.