jc_braconi Posted May 13, 2011 Share #1 Posted May 13, 2011 Advertisement (gone after registration) engraved ins. in place of feet. 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/151639-early-summicron-250-dr-inches-scale-range/?do=findComment&comment=1671202'>More sharing options...
Advertisement Posted May 13, 2011 Posted May 13, 2011 Hi jc_braconi, Take a look here Early Summicron 2/50 DR inches scale range. I'm sure you'll find what you were looking for!
iphoenix Posted May 14, 2011 Share #2 Posted May 14, 2011 JC, is that unusual? My c/r Summicron (1544***) also shows inches, but shows feet at the 4.5 foot mark. Kind regards, David. Link to post Share on other sites More sharing options...
jc_braconi Posted May 14, 2011 Author Share #3 Posted May 14, 2011 JC, is that unusual? My c/r Summicron (1544***) also shows inches, but shows feet at the 4.5 foot mark. Kind regards, David. I just pointed the engraving ins. and not feet or meter or both in the last issues Link to post Share on other sites More sharing options...
luigi bertolotti Posted May 14, 2011 Share #4 Posted May 14, 2011 ...Or all three (ins , not ins.) like in my 1.785.704... but without the reproduction ratios (front engravings in capital - head removed to take these pics... ) 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! The transition inches to feet is (logically) coincident with the divide between the two ranges. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! The transition inches to feet is (logically) coincident with the divide between the two ranges. ' data-webShareUrl='https://www.l-camera-forum.com/topic/151639-early-summicron-250-dr-inches-scale-range/?do=findComment&comment=1671904'>More sharing options...
jc_braconi Posted May 14, 2011 Author Share #5 Posted May 14, 2011 Just to complete the illustration : one (like yours) meter, feet and ins and one in m with reproduction ratio. 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/151639-early-summicron-250-dr-inches-scale-range/?do=findComment&comment=1672035'>More sharing options...
luigi bertolotti Posted May 14, 2011 Share #6 Posted May 14, 2011 ... and now the question is : is the change in scale type (dual-single) related to the change of lettering in front ? I mean, do exist DR Crons with single scale AND capital lettering and vice-versa ? Link to post Share on other sites More sharing options...
jc_braconi Posted May 14, 2011 Author Share #7 Posted May 14, 2011 Advertisement (gone after registration) Are you trying to make a kind of parallel with VIOOH engraving ? the single m is in small letters the same as yours is in capital letters as the one in ins. Link to post Share on other sites More sharing options...
andybarton Posted May 14, 2011 Share #8 Posted May 14, 2011 I bought one of these only yesterday. Does the front come off from the back, then? I will have a look for the inches too - mine's from 1958. SN 1598xxx Doesn't work on an M9. Edit: Mine has inches below the stop and feet / metres above. No reproduction ratios engraved. And, it does look like the front half unscrews, but I'm a bit reluctant to do/ that. What would be the purpose of the removable facility? Link to post Share on other sites More sharing options...
jc_braconi Posted May 14, 2011 Author Share #9 Posted May 14, 2011 I bought one of these only yesterday. Does the front come off from the back, then? I will have a look for the inches too - mine's from 1958. Doesn't work on an M9. Yes it is possible to use the lens head on a bellows or on a special mount for near focusing only. Dangerous to use on M8/9 due to the long "hooked"helicoïd Link to post Share on other sites More sharing options...
andybarton Posted May 14, 2011 Share #10 Posted May 14, 2011 Thanks - I don't think I want to go down that path MIne has "51.9 N" scratched into the black collar around the rear element. I know what this must mean, but it's interesting that even when they didn't engrave the actual focal length on the body of the lens, a technician still marked it. There is a "62" scratched on the other side. I will post a shot in a short while. Link to post Share on other sites More sharing options...
andybarton Posted May 14, 2011 Share #11 Posted May 14, 2011 You could seriously get into this collecting lark, couldn't you? 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! Are these lenses single coated? Thanks. Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! Are these lenses single coated? Thanks. ' data-webShareUrl='https://www.l-camera-forum.com/topic/151639-early-summicron-250-dr-inches-scale-range/?do=findComment&comment=1672401'>More sharing options...
luigi bertolotti Posted May 14, 2011 Share #12 Posted May 14, 2011 Well, Andy, you gave a good opportunity to "restrict" the answer I posed... your s/n is just a bit "younger" than the item depicted by JC (1.598.xxx vs. 1.585.xxx)... but you say that yours has a dual scale mtr/feet (ins) , whilst JC's has a single one.... according to Puts, between your and JC's batches there is only one other batch of Summicrons 50 (1.592.001 - 1.594.000) .... we are probably right within the area of transition from one to the other style... how is the lettering in your item's front ? I'd bet is in capital... but am curios to know if is really so. btw... my item too has "51.9" engraved, plus a "V" (where yours has a "N") and a "4". About coating... I think it's single in items of 50's. Link to post Share on other sites More sharing options...
andybarton Posted May 14, 2011 Share #13 Posted May 14, 2011 My example has lower case lettering. [ATTACH]257541[/ATTACH] Link to post Share on other sites More sharing options...
luigi bertolotti Posted May 14, 2011 Share #14 Posted May 14, 2011 Thanks !!! One of the little curiosities that intrigue collectors... ... so the transition lower-upper case is not coincident with the transition single-dual scale... apparently, the first occurred later... probably items with single scale and UPPER case do not exist... (waiting to be corrected under JC's statement "exceptions are the rule"...) Link to post Share on other sites More sharing options...
jc_braconi Posted May 14, 2011 Author Share #15 Posted May 14, 2011 The m is 1 513xxx 57 the dual is 1 787xxx 60. Link to post Share on other sites More sharing options...
jc_braconi Posted May 14, 2011 Author Share #16 Posted May 14, 2011 ( the font is matching with the barrel engraving ) Link to post Share on other sites More sharing options...
luigi bertolotti Posted May 14, 2011 Share #17 Posted May 14, 2011 ( the font is matching with the barrel engraving ) ... I corrected my above post... time to go to sleep, indeed... but there are the noises of Mille Miglia cars arriving 250 mt from my house... Link to post Share on other sites More sharing options...
iphoenix Posted May 15, 2011 Share #18 Posted May 15, 2011 Thanks JC, for the record mine (1544***) is in inches and feet only, showing "ins." and "feet" in lower case letters. Rgds, David Link to post Share on other sites More sharing options...
iphoenix Posted May 15, 2011 Share #19 Posted May 15, 2011 ... I corrected my above post... time to go to sleep, indeed... but there are the noises of Mille Miglia cars arriving 250 mt from my house... You have my sympathy Luigi ( If I may use your first name ), In the 1950's I lived in Albert Park, Australia and the Formula 1 noise from 1 km was bad (or great) enough. Hope you slept well. Regards, David Link to post Share on other sites More sharing options...
Michael Geschlecht Posted May 18, 2011 Share #20 Posted May 18, 2011 Hello Andy, Multi-coating of commercially available photographic lenses began to be advertised in the early 1970's, I think about 1973, by Pentax w/ the production of their revised 50mm 1.4. It was the previous lens manufactured w/ the new coating process. It showed an improvement over the same lens single coated. Minolta had a process around the same time called Achromatic Coating. It consisted of 2 layers of coatings. Leitz mentioned around that time they had already been doing what they called "staggered coating". They said multi-coating was most useful on either deeply curved surfaces or low refractive index glasses. They further said there was sometimes no noticable improvement in image quality achieved by multi-coating lens elements w/ gently curved lens surfaces made of some high refractive index glasses. They also said that for some time they had already been adjusting the number & type of coating to each surface & to each refractive index involved & had been producing coatings able to suppress reflections equal to Pentax's Multi-Coating. Leitz also said they only counted the optically active coatings as layers while some other companies also counted optically inactive layers when they spoke about how many layers were in multi-coated surfaces. I think single coated lenses produce purple, yellow or brown reflections while multi-coated surfaces often reflect green. An interesting note: I think the process of multi-coating Pentax used was originally developed by a Leitz subsidiary located in Southern California which currently is the Leica which produces Geosystem components. Another note: Leitz invented "Corre-fot" or "Corre-phot" about 1977. I'm not sure of the spelling. It was an early form of auto-focus. I think based on contrast measurement. They sold it to Honeywell. Best Regards, Michael Link to post Share on other sites More sharing options...
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