Summicron Radioactive--Is this true?

[kkdanamatt]

SUMMICRON

This lens was based on a Gauss design modified by Lee of Taylor and Hobson and known as the Cooke Opic lens. It was similar to Zeiss Ikon's Biotar and Sonnar lenses. It is a little known fact that when Summicron lenses were first
introduced they contained radioactive glass. You can identify some radioactive Summicrons by the fact the lens will have a red star engraved on its aperture ring.

 

[Dave Wilkinson]

SUMMICRON

This lens was based on a Gauss design modified by Lee of Taylor and Hobson and known as the Cooke Opic lens. It was similar to Zeiss Ikon's Biotar and Sonnar lenses. It is a little known fact that when Summicron lenses were first
introduced they contained radioactive glass. You can identify some radioactive Summicrons by the fact the lens will have a red star engraved on its aperture ring.

mmm.....that rumour hasn't reached these parts yet! 😉

 

[kossi008]

I don't really know, but I think it's bogus.

First of all, the Cooke triplet, Biotar and Sonnar designs are similar to the Gauss design but, (a) they are not derived from it afaik, and (b) the Summicron is a double-Gauss. So I fail to see the relation between the Summicron and the aforementioned class of lenses.

Second, there have been quite some "radioactive" lenses in the 60s and 70s containing (correct me if I'm wrong here) Thorium Fluoride elements (e.g. the famed Canon FD 35mm f/2 SSC with concave fromt element), but (a) I fail to see what's the big deal here (other than novel optical properties at the time) and (b) I don't think the Summicron ever had that.

I could be wrong on some points, as I am not really an expert in Leica history. So maybe someone else will shed some more light on this?

 

[Sonnar Brian]

The original Summicrons use Thorium Glass and they are radioactive. I own two of them. Summicrons with SN after 105xxxx do not use radioactive glass.

The original prototype Summicrons were marked as Summitars, and had the asterisk (or star) next to the name. I have only seen photographs.

http://www.imx.nl/photo/leica/lenses/lenses/page92.html

The Summar is a double-gauss, 6 elements in four groups, 1-2-2-1 configuration. The Summitar and earlier Summicrons are evolutions of it, 7 elements in 5 groups. The type 2 Rigid Summicron (black, the 70s version) was 6 elements in 5 groups. The modern Summicron went back to the 1-2-2-1 configuration.

 

[Chriscrawfordphoto]

THe very first collapsible summicrons did have radioactive glass, but it was changed to non-radioactive glass during the time the collapsible was made and no summicron 50 since then has had that glass. The radioctive ones are collectibles now.

 

[kossi008]

I stand corrected. Just goes to show I don't know the first thing about summicrons... well well... 😀

It's not even Thorium Fluoride, but Oxide. Shame on me.

 

[Rob-F]

I think that the thorium was an impurity in what was intended to be a glass containing lanthanum. Later, Leica obtained supplies of Lanthanum not contaminated with thorium. A number of Leica lenses have been made with lanthanum glass, designated LAK-9 by Leitz.

Here's what I remember about the history of triplets and Summicrons. The first high-quality lens for photography was developed at Cooke optical, in England, by Taylor. The Cooke firm, having had no interest in producing it, licensed the design to Taylor, Taylor and Hobson (no relation to Mr. Taylor, the inventor of the lens). It became known as the Taylor-Hobson-Cooke Triplet: four elements in three groups, with the rear group being a cemented doublet. The Zeiss Tessar and the Leitz Elmar were both adaptations of this design.

Sometimes in the late 1800's, Dr. Paul Rudolph at Zeiss designed a very high quality fast lens having about six elements. He knew that the lens would have too many reflecting surfaces to be practical--too many internal reflections. He put his design into a file cabinet, where it remained until, after his death, the development of lens coatings made it possible to use Rudolph's design in practical photography. This was the Zeiss Planar and its derivatives, the Schneider Xenotar, Leitz Summitar, Summicron, etc.

I would be hard-pressed to say that the Summicron came out of work done at Cooke; though what I know is undoubtedly just the tip of the iceberg.

 

[Sonnar Brian]

Thorium glass was used as it was a high index of refraction with low dispersion. It is a type of glass in and of itself, not an impurity of Lanthanum glass.

It will light up a Geiger Counter. The Thorium Summicron is unusual as the first element uses Thorium. Most other "hot glass" lenses use Thoriated glass in the interior. I keep a filter over my two. It is an Alpha Emitter.

 

[John Shriver]

Yes, my early Summicron definitely keeps the my Geiger counter excited. I tried bleaching it using a UV light, but it was UVC. Not the right wavelength at all.

 

[Sonnar Brian]

A short explanation of Thoriated Glass by Oak Ridge.

http://www.orau.org/PTP/collection/consumer products/cameralens.htm


Another interestig piece from the same site:

http://www.orau.org/ptp/collection/consumer products/cloisone.htm

I'm going to think twice before buying Cloisonne jewelry from that antique store as a Gift!

 

[Alberti]

Thorium glass was used as it was a high index of refraction with low dispersion. It is a type of glass in and of itself, not an impurity of Lanthanum glass.

It will light up a Geiger Counter. The Thorium Summicron is unusual as the first element uses Thorium. Most other "hot glass" lenses use Thoriated glass in the interior. I keep a filter over my two. It is an Alpha Emitter.

Oh my, will this then expose the film?
Well, for me LOL, the amount of radiation will not be more than the background in many a house.
alberti

 

[Sonnar Brian]

If you leave the lens, face down, on print paper in a darkoom; it will expose the paper.

It will not damage film in a camera.

Do not hit the glass with an axe or hammer. You do not want to inhale the debris.

 

[Rob-F]

I have also read that in such lenses the rear element is made of leaded glass, to block radiation from reaching the film.

This (mis)information may very well be worth what you paid for it.

 

[rxmd]

Oh my, will this then expose the film?
Well, for me LOL, the amount of radiation will not be more than the background in many a house.
alberti

I tried that with two Ektars once, an 178/f2.5 Aero Ektar and an 113/f4.5 Printing Ektar. Both are radioactive lenses. We put a 400-speed 4x5" negative in a changing bag and put the Ektars on top of the changing bag for 48 hours, both with the rear element towards the film. The film got fogged.

Since I'd expect a cloth shutter to be rather thinner than a changing bag, your film might get fogged, depending on which lens element is the thoriated one and on how long you leave the camera without advancing the film.

 

[Sonnar Brian]

Automatic Film Pre-Sensitization...

It's a Feature, not a Flaw!

 

[John Shriver]

Well, lead glass is called "flint glass" when it's used in a lens, and it's been a key ingredient in optical design since the beginning. The front element of Summar and Summitar lenses is soft flint glass, that's why they are so commonly found scratched to hell.

 

[Carterofmars]

Summicrons with SN after 105xxxx do not use radioactive glass.

Brian- are you sure about these serial numbers?

Thanks,

Joe

 

[Sonnar Brian]

I have two in the 104x range that use "hot glass". These lenses were original to Leica IIIf Black Dials. 105x was the cross-over point, and I would expect a couple to pop up- but have never seen one. I've seen some places state that only lenses with Sn under 1Million used hot glass, but know from first-hand experience that this is wrong.

The M-Mount lenses start in the 112x range, well-past the range that used Hot Glass. Personally, I find my later Summicrons in the 13x range to have improved coatings, and are terrific performers. I think this is a case of the lens being tweeked throughout it's production run.

 

[Mackinaw]

Do not hit the glass with an axe or hammer. You do not want to inhale the debris.

Bob Shell, when he was actively involved in photo forums, said that one reason thorium fell out of favor was because of the possible hazard to those who worked in lens manufacturing facilities. I guess making a lens can (or did) produce a lot of fine dust.

Jim B.

 

[Matus]

That may well be true. Alpha radiation has range about 5cm in air and is very easy to shield (it does not penetrate a sheet of paper). But once the radioactive material finds its way in human body it causes heavy damage to the tissue its vicinity. On top of that half lives of alfa emitters are very long and these heavy elements tend to remain in the human body.

Often forgotten point is that the heavy elements (whether radioactive or not) are mostly very poisonous - so the befallen person will more probably suffer the chemical effect rather than radioactive ones.

I feel like I should get one too ...