darigle Posted January 30, 2009 Share #1 Posted January 30, 2009 Advertisement (gone after registration) I am new to this forum and ask if someone can help with why some early lens are marked F=50mm or f=5cm? Was there a changeover date or any reason why some are marked one way or the other. I have just part retired and can now indulge myself in my latent passion for photography. Really interesting forum and look forward to hearing from any who can help Link to post Share on other sites More sharing options...
Advertisement Posted January 30, 2009 Posted January 30, 2009 Hi darigle, Take a look here F=50mm; f=5cm. I'm sure you'll find what you were looking for!
jc_braconi Posted January 30, 2009 Share #2 Posted January 30, 2009 Welcome to the forum, we have discussed here about this subject last year, a members survey have stabilised that from 1930 to 1938 it was mixed mm and cm. from 1938 to 1958 it was used the cm units. from 1958 today, except few example, the mm unit is used. May be the different decade had their use for this different units not only in marking lens but for other subjects. Enjoy your retirement ! (as I am doing ) Link to post Share on other sites More sharing options...
lars_bergquist Posted January 31, 2009 Share #3 Posted January 31, 2009 I think that the switch from millimeters to centimeters occurred already during the late 1920's. Lenses from the 1930's are in centimeters. but the switch back to millimeters did indeed occur in 1958. The very first specimens of the 50mm Elmar 2.8 and the 35mm Summicron were actually engraved in centimeters. This said, Leitz/Leica have never ever manufactured a 50mm lens, regardless of the engraving. From the beginning, the design focal length of "50mm" lenses was 52mm, plus or minus some tenths. For instance, the focal length of the Summilux ASPH is stated to be 51.6mm, while that of the new Noctilux is 52.3mm. But it does round off to 5 cm ... The old man from the Age of Centimeters Link to post Share on other sites More sharing options...
jc_braconi Posted January 31, 2009 Share #4 Posted January 31, 2009 . From the beginning, the design focal length of "50mm" lenses was 52mm, plus or minus some tenths. For instance, the focal length of the Summilux ASPH is stated to be 51.6mm, while that of the new Noctilux is 52.3mm. But it does round off to 5 cm ... The former Noctilux 1/50 are all 50.00 mm Link to post Share on other sites More sharing options...
UliWer Posted January 31, 2009 Share #5 Posted January 31, 2009 I think that the switch from millimeters to centimeters occurred already during the late 1920's. Lenses from the 1930's are in centimeters. but the switch back to millimeters did indeed occur in 1958. The very first specimens of the 50mm Elmar 2.8 and the 35mm Summicron were actually engraved in centimeters.... According to the list of Hartmut Thiele, Kleines Fabrikationshandbuch Leica-Objektive, there were Elmars in 50-mm until 1934 (No. 211.201 - 214.000), though there are lots of Elmars with lower numbers and cm-engravings. Numbered 5-cm Hektors already appeared around 1931 (No.92.301 - 92.900). The last Leica-lenses with cm seem to be the Hektor 4,5/13,5 (1.659.001 - 1.660.000) and the 6 cm Fokotar (1.701.001- 1.701.500) for which Thiele gives 1959 as year of production. Link to post Share on other sites More sharing options...
jc_braconi Posted January 31, 2009 Share #6 Posted January 31, 2009 According to the list of Hartmut Thiele, Kleines Fabrikationshandbuch Leica-Objektive,. I have this book, have found some errors inside; have heard the author collected informations from collectors not from the factory. Link to post Share on other sites More sharing options...
UliWer Posted January 31, 2009 Share #7 Posted January 31, 2009 Advertisement (gone after registration) I have this book, have found some errors inside; have heard the author collected informations from collectors not from the factory. I do not know which sources Thiele exactly used. He explains, that information by Leica itself in many cases where incomplete. If there are errors why should collectors not correct them, or just fill the gaps left open by Leica information? Link to post Share on other sites More sharing options...
darigle Posted February 1, 2009 Author Share #8 Posted February 1, 2009 Thanks to all of you for your replies. Its a real pleasure to be in the company of so many who have such a wide range of knowledge and experience and are prepared to share it. I look forward to engaging in the community in the future. Its a great resource; again thanks:) Link to post Share on other sites More sharing options...
jc_braconi Posted February 1, 2009 Share #9 Posted February 1, 2009 If there are errors why should collectors not correct them, or just fill the gaps left open by Leica information? Must collect a certain lot before reediting an another issue. Link to post Share on other sites More sharing options...
lars_bergquist Posted February 2, 2009 Share #10 Posted February 2, 2009 Most lens manufacturers do not publish actual design focal lengths. Leica do, nowadays, and I did mention some recent examples. Have Leitz/Leica ever produced a statement that the f.l. of the v.2 Noctilux was EXACTLY 50.00mm, and not just nominally 50mm? If so, I have not seen it. Had Leitz Canada actually produced an exactly 50.00mm Noctilux, they would certainly have gone against the stream, for most manufacturers did found it easier to produce their superspeed standard lenses in lengths of 55 or even 57mm--and admitted it! But to cite another example, the v.2 (rigid) 50mm Summicron had its optical cell assembled selectively into focusing mounts for the modal lengths of 51.6, 51.9 and 52.2mm, which you will find scratched into the cell mounting if you unscrew it. (The cells were tested and sorted for focal length after assembly.) The focusing mount in turn was coded under the focusing tab, with either the actual length or a code numeral or letter. The Dual Range Summicron did always carry lens cells of 51.9mm length. The old man from the Age of 55mm Lenses Link to post Share on other sites More sharing options...
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