wizard Posted March 13, 2020 Share #41 Posted March 13, 2020 Advertisement (gone after registration) Am 6.1.2020 um 14:50 schrieb jaapv: The cause was that the glass smelting furnaces were contaminated by Thorium. So early non-Thorium lenses can exhibit brown/yellow discolouration through radio-activity. Jaap, this might be true if the producer of the glass would have been the same. However, to the best of my knowledge, the radioactive glass was produced by Chance Brothers (presumably in England), whereas the LaK9 glass used for the later lenses came from a German producer (presumably Schott). So it seems unlikely that Schott's glass melting pots were contaminated with Chance Brother's Thorium . Link to post Share on other sites More sharing options...
Advertisement Posted March 13, 2020 Posted March 13, 2020 Hi wizard, Take a look here Is there any M-mount radioactive Summicron 50/2 ?. I'm sure you'll find what you were looking for!
luigi bertolotti Posted March 13, 2020 Share #42 Posted March 13, 2020 (edited) Iirc, the problem of "contamination with Thorium" was intinsic of the first (someway experimental) production runs of the LaK9, which was initially developed inside the Wetzlar lab - and later outsourced when the formula and process was definitely assessed : it's true that the very first glasses (Thorium based) came from Chance Brothers : according to Marco Cavina, the Chance Br. glass was used in Summitar* 812.242 to 812.320 (which, btw, close to f 22), and only in the very first Summicrons (920.001 to 920.072) : those ought to be the real ! / original ! / pure ! radioactives... 😁 Edited March 13, 2020 by luigi bertolotti Link to post Share on other sites More sharing options...
alan mcfall Posted March 14, 2020 Share #43 Posted March 14, 2020 Thiele's list from factory records, shows: 920001-922100 and 993001-996000 as the earliest Summicrons. They could be referred to as the "six digit summicrons". I have recorded over 100 of these and have 920109, 920218 and 920838 which are tested as radioactive. I also have 921255 and 921965 which have brown-yellow glass, but have not been tested yet. I had noted the transition to non-radioactive to be 922072, but have seen no convincing evidence. How the "carry-over" use of contaminated glass melting hardware might be seen, I would expect the radioactivy to be decreased. Again, bettter factory records would benifit us all. I have recorded many summicrons between 922100 and 923000, so the Thiele lists may not be accurate with respect to the ending of the first lot. It is not uncommon to see leitz production continue on into unassigned following lots. I have not recorded any M summicrons in these first 6000 or so production. My first bayonet summicron is 1044534 and others have been recorded such as 1042xxx. Thiels list the first as 1114001, so again this is clearly not perfectly true. The photo of 920505 in the above post as a bayonet lens is surprising (920507 is a screw mount). As others have mentioned, it could be a test lens for the M camera, pulled from prodution, but seems too early. A deeper examination of the mount is needed. And, as a reminder, the front lens retaing ring, containing the serial number and more, is interchangable for the first many years of summicrons. Early and late could be switched however unlikely. Earliest would not have the Gmbh, later would. For those wishing a "radioactive" lens, I would suggest that a serial below 922072, with preferrably detector testing proof as a safest bet. Lens visual coloring alone may have some risk. Lenses over 1 million, claimed to be radioactive, and they may me, should definitily be tested. 2 Link to post Share on other sites More sharing options...
luigi bertolotti Posted March 14, 2020 Share #44 Posted March 14, 2020 14 hours ago, luigi bertolotti said: ... the very first glasses (Thorium based) came from Chance Brothers : according to Marco Cavina, the Chance Br. glass was used in Summitar* 812.242 to 812.320 (which, btw, close to f 22), and only in the very first Summicrons (920.001 to 920.072) : those ought to be the real ! / original ! / pure ! radioactives... 😁 Reading Alan post, 920.072 must be a typo in Cavina' site... 922.072 looks much more reasonable. Link to post Share on other sites More sharing options...
PG Black nickel Posted March 15, 2020 Share #45 Posted March 15, 2020 Hello, I do not have a radioactivity tester to check, but what I can confirm is that this objective N ° 920505 if it was modified, it was it by a professional, there is really no screwdriver on the screws. it appears as new, as having been used very few times. Did the M3 testers keep their device for a long month or only use it for a short time ? Link to post Share on other sites More sharing options...
PG Black nickel Posted April 16, 2020 Share #46 Posted April 16, 2020 Hello I hope you are all healthy and so is your family. A little back on the old summicron, did you see that a prototype (N°920168) was on sale at the Leitz Photographica auction in June, its estimation 100.000 to 120.000 €...oops !!! As a reminder the N°920139 it is sold for 8400 € in 2008 at Westlicht...! At this amount I will put my old M 920505 for sale at the next sale in October !!! Take care. Link to post Share on other sites More sharing options...
wizard Posted April 16, 2020 Share #47 Posted April 16, 2020 (edited) Advertisement (gone after registration) vor 4 Stunden schrieb PG Black nickel: ... did you see that a prototype (N°920168) was on sale at the Leitz Photographica auction in June, its estimation 100.000 to 120.000 €... I just had a quick look at that prototype 920168 Summicron. It differs markedly from the later serial production version of the first M Summicron 50 mm lens. First, it has two levers instead of just one. Second, the parts of the lens where the meter scale and depth of field markings are engraved are different from the later serial production lens. So this one is clearly a prototype lens. Does your lens look the same? If so, lucky you! Stay safe and healthy. P.S.: I just realized you have shown your lens already, and it looks like a regular serial production lens. If the serial number of your lens is the correct number of that lens, then it might still have some collector's value (though very likely not in the 6-digit range) Edited April 16, 2020 by wizard Link to post Share on other sites More sharing options...
luigi bertolotti Posted April 17, 2020 Share #48 Posted April 17, 2020 21 hours ago, PG Black nickel said: Hello I hope you are all healthy and so is your family. A little back on the old summicron, did you see that a prototype (N°920168) was on sale at the Leitz Photographica auction in June, its estimation 100.000 to 120.000 €...oops !!! As a reminder the N°920139 it is sold for 8400 € in 2008 at Westlicht...! At this amount I will put my old M 920505 for sale at the next sale in October !!! Take care. Leitz Photographica Auction is a serious organization : my advice is to send them, initially, a good set of pictures with details of your item (mount, interior of tube...) asking them what they think about (is a funny exercise to make... I did it a pair of times...) : they are always looking for uncommeon items for their auctions (of course, not for glory.. they take their share... 😉) and in case they are interested in auctioning it, they'll probably will ask you to send the item for a correct evaluation. Link to post Share on other sites More sharing options...
PG Black nickel Posted April 17, 2020 Share #49 Posted April 17, 2020 Thanks Luigi for the advice, I've also already sent some cameras to them, sometimes I was disappointed and sometimes very surprised by the bids that went up very high. I'm a bit like all collectors, to be able to buy the cameras of one's dreams you sometimes have to sell some of the beautiful ones. I also asked Lars Netopil who works at Wetzlar camera auction if he could give me some information about these old summicron screw mount upgraded to M-mount. But I don't know them, they have just started selling cameras and I looked at their previous sale where there were some very nice and rare cameras. I don't know if you used to go to the Bièvre fair (biggest old cameras fair in the world), but unfortunately this year it's cancelled !!! See you next year ! Take care ! Link to post Share on other sites More sharing options...
PG Black nickel Posted April 17, 2020 Share #50 Posted April 17, 2020 Wizard, unfortunately mine has only one lever ! but is probably part of the old screw-mount upgraded to M-mount for the M3 camera test. I was talking about the Summicron prototype which was sold at Westlicht in June 2008 sale N° 13 lot 93 which also has two levers, the seller of this lens if he sees today's estimates must be sick !! Take care Link to post Share on other sites More sharing options...
Pyrogallol Posted April 17, 2020 Share #51 Posted April 17, 2020 The two lever prototype is illustrated in one of Lager’s guides, top left corner of the page. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/305067-is-there-any-m-mount-radioactive-summicron-502/?do=findComment&comment=3955383'>More sharing options...
PG Black nickel Posted April 17, 2020 Share #52 Posted April 17, 2020 Thank you, Pyrogallol, But it's very complicated to follow the serial numbers of Leica, the prototype on James Lager's book is the number 1480824 which corresponds to the year 1957 and moreover there were only screw- mounts built that year! This prototype was certainly built at the same time as the M3 prototypes, in the years 1952/53 but can be restored later? with a new crown? Except the guy who made it we'll never know why this number ! Link to post Share on other sites More sharing options...
dumplings Posted August 31, 2022 Share #53 Posted August 31, 2022 Just found out my 1042406 (1952) is also M mount and tested not hot. Purchased on ebay with a 1959 M3. Still does not quite know what happened to this lens. Could it be sent to the factory and updated from screw to M mount? It has . not comma ',' on the aperture ring. Link to post Share on other sites More sharing options...
luigi bertolotti Posted August 31, 2022 Share #54 Posted August 31, 2022 5 hours ago, dumplings said: Just found out my 1042406 (1952) is also M mount and tested not hot. Purchased on ebay with a 1959 M3. Still does not quite know what happened to this lens. Could it be sent to the factory and updated from screw to M mount? It has . not comma ',' on the aperture ring. Probably your 1042406 was born as a M mount item at the factory : see the Lager's page above posted, where he displays a M mount item with a serial number very close to yours : the fact that batch 1040001 1045000 is described as made by Screw Mount items in Wiki (and other sources) is surely an all but definitive statement... Summicron was made in big numbers, in a timeframe when M3 was made also in big numbers... the original planning of batches was surely subject to update/modify as orders had to be fullfilled. 1 Link to post Share on other sites More sharing options...
PG Black nickel Posted September 3, 2022 Share #55 Posted September 3, 2022 Hello to all Another one of those mystery summicron M mount with a screw mount serial number ! For sale at Auction team breker in Cologne... Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/305067-is-there-any-m-mount-radioactive-summicron-502/?do=findComment&comment=4502638'>More sharing options...
wlaidlaw Posted September 3, 2022 Share #56 Posted September 3, 2022 (edited) By the time you add their buyer fees on top of that starting bid, it is beginning to look expensive. My guess is also that it might just be a "Bitza" lens (bits of this together with bits of that). Wilson Edited September 3, 2022 by wlaidlaw Link to post Share on other sites More sharing options...
Anbaric Posted September 4, 2022 Share #57 Posted September 4, 2022 On 3/13/2020 at 7:32 PM, luigi bertolotti said: Iirc, the problem of "contamination with Thorium" was intinsic of the first (someway experimental) production runs of the LaK9, which was initially developed inside the Wetzlar lab - and later outsourced when the formula and process was definitely assessed : it's true that the very first glasses (Thorium based) came from Chance Brothers : according to Marco Cavina, the Chance Br. glass was used in Summitar* 812.242 to 812.320 (which, btw, close to f 22), and only in the very first Summicrons (920.001 to 920.072) : those ought to be the real ! / original ! / pure ! radioactives... 😁 Since this thread is active again, one thing I recall from an article by Marco Cavina is the claim that radioisotopes (potentially including thorium) may also end up in lanthanum glass because they are present in the monazite sands from which lanthanum is extracted, and it can be difficult to remove them completely. https://www.photo4u.it/viewtopic.php?p=1530804&sid=c5ec04985b78ebb71e494ca5efa4220f I've no idea of how accurate this claim is, or how significant any contamination might be. 1 Link to post Share on other sites More sharing options...
wlaidlaw Posted September 5, 2022 Share #58 Posted September 5, 2022 I have been told that the yellow discolouration can be "cured" by shining a very powerful UV light through the lens for an hour or so. That seems a bit unlikely to me as I assume the discolouration is a chemical or isotopic change in the composition of the glass, resulting from being struck by alpha particles from the thorium. If isotopic change, I cannot see the mechanism by which UV light would change that back. Wilson Link to post Share on other sites More sharing options...
frame-it Posted September 5, 2022 Share #59 Posted September 5, 2022 19 minutes ago, wlaidlaw said: I have been told that the yellow discolouration can be "cured" by shining a very powerful UV light through the lens for an hour or so. That seems a bit unlikely to me as I assume the discolouration is a chemical or isotopic change in the composition of the glass, resulting from being struck by alpha particles from the thorium. If isotopic change, I cannot see the mechanism by which UV light would change that back. Wilson on my radioactive industar, the yellow-brown tint disappears after 3-4 hours of walking around in the sun Link to post Share on other sites More sharing options...
AndreasG Posted September 5, 2022 Share #60 Posted September 5, 2022 vor einer Stunde schrieb frame-it: on my radioactive industar, the yellow-brown tint disappears after 3-4 hours of walking around in the sun What happens with the shutter curtains, do you close the aperture? Link to post Share on other sites More sharing options...
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