Radioactive Leica 50mm f2 Collapsible Summicron (M39) good idea as only Lens?

[Jerry Attrik]

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Bit of a post-script.

From Wlaidlaw #12 26 March 2018

I too have a Cannon 50mm; f1:1·8 but it is the one with the black focussing barrel, bought 1962.

I put a UV filter on it immediately from element is pristine the  image quality is excellent.

[jaques]

On 5/28/2019 at 6:27 AM, Jerry Attrik said:

I

A drop or two of lens cleaning fluid and flick it off with barely a touch using a sable or squirrel hair brush. 

Cloth will always have some kind of dust in it, a brush can be cleared of dust by flicking it across a finger-nail or other clean  hard edge.

do you then wash the brush? In water? I have quite a few vintage lens brushes (lipstick style) that seem to be animal hair of some kind- would these do? They are super soft and in good order. I'd be worried they would leave lens fluid residue? I usually breathe on a lens element for a second wipe (with fresh dry lens paper) to remove the smears of fluid...

Edited June 4, 2019 by jaques

[Jerry Attrik]

17 hours ago, jaques said:

do you then wash the brush? In water? I have quite a few vintage lens brushes (lipstick style) that seem to be animal hair of some kind- would these do? They are super soft and in good order. I'd be worried they would leave lens fluid residue? I usually breathe on a lens element for a second wipe (with fresh dry lens paper) to remove the smears of fluid...

If you can be sure the brushes are not ladies make-up brushes and if the hair is mid-brown it is likely to be squirrel but you say 'supersoft'  they could be sable (the best).

I have used Johnson's lens cleaning fluid, until my bottle ran empty.  I have not found a replacement which seems to have the same formula.  The Johnson formula evaporated completely so no 'after cleaning' was needed. I fear that human breath will contain greasy gunk from lungs which would leave a surface film.  I have not washed my brushes  in tap water because it might contain dissolved chlorine and will contain dissolved minerals and suspended microparticles which could act as a fine scouring powder and dull the lens surface,

I have provided all my lenses with filters on a prevention is better than a cure.  The potential small loss of image quality I sacrifice to be preferable than a replacement lens.

[alemartinezc]

On 5/27/2019 at 9:54 AM, ckuwajima said:

Hi, according to this Japanese article (http://www.sky.sannet.ne.jp/seven-ss/camera/summicron50.htm), there are radioactive Summicrons with serials over 1.000.000.

I have one with serial 1.042.xxx that has all the characteristics of a radioactive lens (yellowish glass, aperture ring, etc.).

I also have a radioactive Summicron according to this Japanese  article. And over 1.000.000

https://flic.kr/p/2gatS8G

[alemartinezc]

Finally I was able to upload properly the image...

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[Stacey]

On 6/4/2019 at 5:20 PM, Jerry Attrik said:

 

I have provided all my lenses with filters on a prevention is better than a cure.  The potential small loss of image quality I sacrifice to be preferable than a replacement lens.

Yes, I normally am not a "protective filter" advocate, but on these old lenses like this with soft glass, 100% agree.

 

[tobey bilek]

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ok for monochrome.   Color pics will pick up a yellow cast as if you took color thru a yellow filter.

There a methods to remove color cast with UV light.  May or may not work long term.  I was offered one that was mint ++++++ but had the yellow.  I sent it back.

 

 

 

 

 

 

 

[huubl]

I have had (now sold) a radioactive LTM summicron #1024500 which was pretty radioactive. With the gm counter on top it counted 300 cps vs background 2 cps. 

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Still have #1021748, equally radioactive. Both have yellowed front glass and make superb B&W images. Even though one of them has heavily pitted front glass. 

[Anbaric]

On 5/27/2019 at 9:57 PM, Jerry Attrik said:

I have a thorium dossed 'Cron  Nr. 1104466 which I have been using on a 3f. for 47 years.

Thorium is an alpha emitter and there will be some gamma radiation. The alphas will not get out of the glass and the gammas have never caused film fogging.

Ergo - not a problem for humans, unless one grinds the glass to a powder and eats it.

I wouldn't use it as a loupe, either, or keep it on my nightstand:

https://www.orau.org/ptp/collection/consumer products/cameralens.htm

[roydonian]

When taking a couple of comparison shots yesterday, I noticed that imagery from my 5cm Summicron 1396624 has a slight yellow cast when compared with those from an f2.8 Elmar and a type 2 Summilux. I wonder why this should be - it seems too high a serial number to have radioactive elements. I wonder if this problem is due either to evaporated lubricant or by a previous owner having been a heavy smoker, so could be fixed by getting the lens cleaned.

[Jerry Attrik]

I did read, a couple of years ago, in web post someone described a Summicron as producing 'warm' images.

But never discovered if this referred to a thorium or a non-thorium lens.

Huubl (#31, june 28) shews a rate meter indicating 300Bq. I have to assume this is gamma.

The lens itself contains, if my sums were correct, 6kBq. to 7kBq. of thorium as alpha.

It would be interesting to use a probe and meter scaled in Sievert.

D.Lox

 

 

[Dvpnyc]

I saw that the new 2019 Tamarkin auction catalogue has one listed with a 12xxx number and in description is says “possibly contains radioactive element despite high serial”. Pure speculation or they know something?

here is a picture of mine that also happens to be 12xxx series with pristine glass. Pictures have a slight yellow /warm cast compared to my rigid and DR. 

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I am thinking of selling it - already have the other two “better” crons. Will I regret it given it is in pristine shape optically (zero cleaning marks) 

your thoughts?

dimitry 

 

 

[spydrxx]

Yes, you'll probably regret it, but it may take a while. It took me about 8 years before I regretted selling mine...but only a little regret....not enough to buy another.

[Dvpnyc]

I feel like this lens is a bookend to my collection of older Leica glass that is both reasonably priced and I can use whenever I want to produce nice photos. But the question is - what does this collapsible offer optically that the other two original Crons don’t? I suppose the collapsible Cron justification to keep or sell is more emotional vs logical. 

[Dvpnyc]

I feel like this lens is a bookend to my collection of older Leica glass that is both reasonably priced and I can use whenever I want to produce nice photos. But the question is - what does this collapsible offer optically that the other two original Crons don’t? I suppose the collapsible Cron justification to keep or sell is more emotional vs logical. 

[david strachan]

Well i still like my Summicron 50mm f2 ltm. Built in 1952, i find it sharp enough, good in corners and not so rudely contrasty.  The images are very malleable.  The only Leica 50mm i own in fact, and one of my favs.

It did take some searching to find one without any marks on the body, and more particularly the front and rear glass.  Then had it serviced, and regreased.

I suppose it might have cost close to US$900 to get this far including, iirc three returns, cleaning, etc.

I can recommend as a very charming lens.

...

Edited October 17, 2019 by david strachan

[wlaidlaw]

If you have a friend who is a dentist, he will probably have a high intensity UV light source, used for setting epoxy fillings. A few minutes with this may well get rid of a lot of the yellowing. I used a physiotherapist's "Chromaya" high intensity UV light, that my wife used to have, on a yellowed lens. She did not replace it when it died, as UV treatment has fallen out of fashion nowadays, I am guessing because of the fear of melanomas. You can buy UV lamps for hardening nail gel quite cheaply (£5 to £10) but I don't know if their intensity and frequency would be suitable for bleaching lenses. 

Wilson

[Guest]

Light curing light looks like UV-light because it is blue. And one could only imagine the problems if dental fillings were made out of epoxy. Where‘s Jaap tonight  ?

However many dental lab technicians have UV light for the hardening of individual impression trays.

The easiest solution is imo to go to a sun bed outfit downtown (or in a gym) and put the lens in front of a smaller face&chest UV  light. There still are people using them beginning this time of the year.

[JMurr33]

I have been using a radioactive Summicron for decades.  I have not experienced any problems in images, but I have grown several additional fingers and toes and, sadly, not on my hands and feet.

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[M9reno]

I had three of my collapsible Summicrons tested in a local particle physics lab.  Here are the results:

The thorium content appears on the line (the "2.6 MeV line") towards the right hand end of each graph (circled).

The ambient background (bottom chart) gives 41 counts per 242,134 sec (margin of error of 9 counts).  

Mantle lamps owned by the lab (middle chart) give 216 counts per 170 seconds (margin of error of 20 counts).  

My radioactive Summicron (top chart) s.n. 1.023.719 gives 286 counts per 171 seconds (margin of error of 23 counts). As expected, a lot more radiation comes out the front than the back.

As a control, I brought along two other lenses.  Collapsible M39 Summicron s.n. 1.104.279 effectively emitted zero radiation.

However..... collapsible *M-mount** Summicron s.n. 1.115.862 was also thorium-contaminated, even if 4/5 less than its 1951 sibling:  58 counts per 180 seconds (margin of error of 10 counts).  

I don't think I've ever read 1954 M-mount Summicrons were thorium-contaminated. But mine is.

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