Writing inside Elmar 9cm

[Giuliobigazzi]

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Hey can anyone tell me what this writing inside this lens is? I recognise the focal lenght and the last four digits of the serial number but not sure about the KU and the other part..

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[UliWer]

My guess is that one person "WStr." (?) measured the exact focal length of the lens head as being 90mm (they may have differed as with the 50mm Elmar), and the second person  "KU" (?) calibrated the shaft for 90mm.

My 90mm Elmar 962068 has a similar engraving:

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So "WStr." seemingly was working on my Elmar as well, though it was "H.G" who did the calibration - if my theory is right.  My other very early "slim" 9cm Elmar 165119 only has the "90" - at least I don't find any other handmade engravings.

 

[Giuliobigazzi]

How about that, that’s the same writing! This should place my lens repair in the same year or similar, for sure it’s had work done(nr.)the double f4 aperture points to a Friday afternoon!

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[UliWer]

I don't know whether the engravings do signify a lens repair. They may have been applied during the original production. If "WStr." stands for a certain person it would not be unusual that he (or she?) was in charge of your example in 1947 and mine in 1952. The wrong aperture point "4" instead of "4,5" may not be his (or her?) fault as the painting may have been applied after the calibration of lens head and shaft. If your lens had been at the factory for a later repair they probably would have corrected the fault (and devalued it from the collector's point of view ...).

[dpitt]

Will van Manen told me once that these shafts and lens parts are matched. So they had to mark them during production to keep both matching parts together. So part of the numbers there are used to match them...

[Giuliobigazzi]

On 2/2/2024 at 1:16 PM, UliWer said:

I don't know whether the engravings do signify a lens repair. They may have been applied during the original production. If "WStr." stands for a certain person it would not be unusual that he (or she?) was in charge of your example in 1947 and mine in 1952. The wrong aperture point "4" instead of "4,5" may not be his (or her?) fault as the painting may have been applied after the calibration of lens head and shaft. If your lens had been at the factory for a later repair they probably would have corrected the fault (and devalued it from the collector's point of view ...).

I suppose so, but this would mean a black paint example from the 50s.. is that even possible? I’ve asked Leica for a delivery date 

[willeica]

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On 2/3/2024 at 10:13 AM, dpitt said:

Will van Manen told me once that these shafts and lens parts are matched. So they had to mark them during production to keep both matching parts together. So part of the numbers there are used to match them...

This is correct and there is a history to this. The numbering system (a table of numbers with various focal lengths) behind focus tab of the 50mm Elmar is well known - do I need to show them again? This was so that the lens could be matched with the correct mount for its true focal length would be added so that the required focal length would be achieved. Originally, the 50mm lenses were matched to a camera using a small hole at the back and a ground glass screen ( similar to 19th Century practices). Metal shims were used for adjustment . Then when the LTM Non Standardised Camera was introduced, they continued to match the lenses using either shims or a range of matched mounts. The matching numbers from the camera SN were engraved on the lenses - a practice which originated in Britain with the Sinclair conversions for Dallmeyer lenses - see my recent YouTube Video linked from another thread here. When the Standardised LTM mount marked with a '0' with a matching '0' on the lenses was introduced there were still some issues to be dealt with, including true focal length. Much testing was done in the optical department at around this time, particularly by Zuhlcke, the foreman. He sent the results of these to Barnack with a view to drawing up a system that would work, for finding matching lens heads and mounts. There are quite a few of these in Ulf Richter's book, 'Barnack from the Idea to the Leica'. Some examples from Zuhlcke, one on behalf of Berek, are below. Zuhlcke was a key figure in this process and reported directly to Barnack on the matter.  Please don't interpret these as the 'last word'. There are other tables relating to lenses in the book and Richter does not reach technical conclusions, he just shows that such testing took place. In order to reach a proper conclusion one would see all of the papers, which I understand are not in the Leica Archive, but rather sit in Peter Karbe's department, which is the current day successor to Derek's department. 

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I believe that such practices continued for some time with all focal lengths, until the manufacturing tolerances became absolutely reliable. The writing inside the 9cm lenses seems to be for the purpose of matching the lens head with a suitable mount during the manufacturing process. I think that I have seen true focal length number tables for lenses other than the 50mm Elmar and the 9cm Elmar may have such a table, but I have forgotten where I saw this. Perhaps Jerzy might remember. 

William 

[jerzy]

Yes William, I know it for Summicron 90mm, 3 groups have been defined, for focal length 89,5mm 90 and 90,5mm. I am not aware about grouping for other 90 and 135mm lenses. However matching the mount to the optics has been done for each Elmar 9cm and Elmar/Hektor 135mm and lens number was scribed into the mount either full of last few digits.
Function of the mount is to keep optics in focus in the whole distance range. With  longer lenses (90, 135,etc) optics extract more at 1m than for 5cm. The same effect is with variations of real focal length for 5cm lenses. We may see it in the letter which you shown above, dated 22.04.1932. Letter says, that from now on all Elmars 5cm for Leica II have the same, identical distance scale engraved and the problem resulting from variations in real focal length is solved by variations in pitch. 3 focal length groups have been defined, middle column named "Steigung" means pitch and pitch is bigger for longer focal length. This means that optic extracts more at 1m. Interesting are the names of groups: short, long and 52.
Interesting is as well the handwritten notice. It predates above machine written notice and takes longer focal length into consideration. It was not yet included in the first definition of focal length groups but it was later. Rotation of 316 degree indicates that it relates to lenses with 11 oclock mount

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Back to Elmar 9cm (and as well 135mm) - I believe that due to relative small initial aperture (4,5) impact of real focal length on focusing accross the distance range was so small that it could have been neglected (differenttly for Summicron where opening of f2 gave much narrower depth of field). But initial focus setting, (at infinity I suppose) must have been set. And it was done by adjusting one ring within the mount, was done when assembling and could have been done as well in the field, in repair shop. On the contrary, mounts for lenses with defined focal length group have been machined in a special way - they had special machines to cut the thread simultanously on both parts of helicoid. Whenever mount had to be renewed in the field the repair person had to specify focal length group in the order to Leitz.
And lastly - this is as well 9cm Elmar and while from approx from the same time as the lens from Giulio, it was another person who scribed it.

Edited February 6, 2024 by jerzy
spelling

[willeica]

12 minutes ago, jerzy said:

Yes William, I know it for Summicron 90mm, 3 groups have been defined, for focal length 89,5mm 90 and 90,5mm. I am not aware about grouping for other 90 and 135mm lenses. However matching the mount to the optics has been done for each Elmar 9cm and Elmar/Hektor 135mm and lens number was scribed into the mount either full of last few digits.
Function of the mount is to keep optics in focus in the whole distance range. With  longer lenses (90, 135,etc) optics extract more at 1m than for 5cm. The same effect is with variations of real focal length for 5cm lenses. We may see it in the letter which you shown above, dated 22.04.1932. Letter says, that from now on all Elmars 5cm for Leica II have the same, identical distance scale engraved and the problem resulting from variations in real focal length is solved by variations in pitch. 3 focal length groups have been defined, middle column named "Steigung" means pitch and pitch is bigger for longer focal length. This means that optic extracts more at 1m. Interesting are the names of groups: short, long and 52.
Interesting is as well the handwritten notice. It predates above machine written notice and takes longer focal length into consideration. It was not yet included in the first definition of focal length groups but it was later. Rotation of 316 degree indicates that it relates to lenses with 11 oclock mount

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Back to Elmar 9cm (and as well 135mm) - I believe that due to relative small initial aperture (4,5) impact of real focal length on focusing accross the distance range was so small that it could have been neglected (differenttly for Summicron where opening of f2 gave much narrower depth of field). But initial focus setting, (at infinity I suppose) must have been set. And it was done by adjusting one ring within the mount, was done when assembling and could have been done as well in the field, in repair shop. On the contrary, mounts for lenses with defined focal length group have been machined in a special way - they had special machines to cut the thread simultanously on both parts of helicoid. Whenever mount had to be renewed in the field the repair person had to specify focal length group in the order to Leitz.
And lastly - this is as well 9cm Elmar and while from approx from the same time as the lens from Giulio, it was another person who scribed it.

Thanks, Jerzy for this technical explanation of what I was trying to say. It is obvious that some modern day technicians such as Will Van Manen and yourself understand what is needed for older lenses. The need for lens/mount matching at Leitz (and indeed elsewhere) seemed to have lessened as time went by and manufacturing tolerances became better, but, even today, all lenses are tested for correct focus and coverage during the final stages of manufacture. 

William 

[Giuliobigazzi]

I’ve heard from Leica who told me this lens was delivered on 2 September 1948, to Wetzlar. Could this indicate a lens used in the factory?

[ph.]

My  former summicron 50mm had 52 pencilled inside. I assume that was for the helix munt to be correspondingly matched.

p.