Serial number patterns of screw mount Leicas - use of "No" vs "Nr"

[ApoVision]

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Does anyone have information about when Leica started to replace "No" sign (the "o" being underlined) before the serial number on the top plate with "Nr."? A cursory google image search seems to insinuate that this must have been around 1950 (No 500 000).

Also, whereas most "Monté en Sarre" (1949 - 1951) have the "No" sign, there is some usage of "Nr." (359 122; 359 495; 359 312)

Is such a "naming convention" one of these things where Leica potentially paid less attention and where there existed no clear SOP? Or - is there an informed decision that was consistently applied (which I may not be able to see)?

Thanks for your help.

 

 

[UliWer]

I don‘t think you‘ll find a precise number on a lens where the engraving with „No.“ stopped and „Nr.“ started. 

Lager lists (but does not show) a 13.5cm Hektor 824421 and a 9cm Elmar 873054 with No. Though he also shows a 5cm Summarit 491931, a Summitar* 812276 and a 12.5cm Hektor 753029 with Nr.

One reason for this „inconsistency“ is that the lens production did not happen in a strictly numerical sequence. Numbers were assigned to a certain batch of lenses (or cameras) in advance and it happened that later batches of different items - with higher numbers - were produced earlier than batches with lower numbers. 

You‘ll see the same mixture of numbers with lenses engraved with cm or mm. 

[jerzy]

vor 4 Stunden schrieb UliWer:

One reason for this „inconsistency“ is that the lens production did not happen in a strictly numerical sequence

same for the cameras. We need to take into consideration that cameras were sometimes repaired, replacing top cover and this could falsify the findings.
Like example below - all cameras on the left are stepper IIIc, 379577 was not upgraded to IIIcf but I believe that the top cover has been replaced early 50-ties, when spare stepper top covers were still available and serial was engraved then. Right photos show very early non-stepper and later sharkskin, both still with No

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Some estimate when switch happened can be seen here, but more examples are needed to be quite sure about when it was (1951/52)

[ApoVision]

Thank you all - very helpful. 

My perliminary hypothesis is:

Leicas that have not been converted and Leicas the top plate of which was not changed usually have the "Nr." sign if their serial number is >= 500 000; otherwise they usually have the "No" sign.

Photos are from Leitz-Auction (thanks!).

 

 

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[UliWer]

1 hour ago, ApoVision said:

My perliminary hypothesis is:

Leicas that have not been converted and Leicas the top plate of which was not changed usually have the "Nr." sign if their serial number is >= 500 000; otherwise they usually have the "No" sign.

No. 537781 shown by jerzy in #3 seems to contradict your hypothesis. 

For lenses the engraving seems to depend on the lens types. Lager shows a very early Hektor 1:2.5/12.5cm 753029 with Nr. but assigns „No.“ to a Summarex 1008349 (though unfortunately the lenses front is not shown). 

 

[jerzy]

vor 9 Stunden schrieb ApoVision:

"Nr." sign if their serial number is >= 500 000; otherwise they usually have the "No" sign.

Leica 500 000 is a special case, cameras with similar special numbers were usually presented to "special" people, they were produced whenever there was a need to honour the person, these numbers were taken out from regular production

[ApoVision]

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thank you; will look for additional numbers greater 500k

[ApoVision]

9 hours ago, UliWer said:

No. 537781 shown by jerzy in #3 seems to contradict your hypothesis. 

For lenses the engraving seems to depend on the lens types. Lager shows a very early Hektor 1:2.5/12.5cm 753029 with Nr. but assigns „No.“ to a Summarex 1008349 (though unfortunately the lenses front is not shown). 

 

Sorry for dissenting, I used the word "usually" in the sense of "statistically significantly", "more often than not", not: "always". Thanks

[UliWer]

Yes, of course! Statistically there are more items with „Nr“ than with „No“ if the engraving was changed with Nr 540 000 (approximately). Your hypothesis is very well founded.