Help with marking on summar

[ChrisLivsey]

For a project I have in mind I have recently acquired an uncoated 5cm f2 Summar (217254 serial). There is a letter "A" engraved/stamped on the rear of the infinity lock. Is this usual and does it have any significance ?

[M. Valdemar]

It's more expensive than the ones marked "B", and the ones marked "C" are rarer than hen's teeth.

[sepiareverb]

Stands for 'annoying'.

I have no idea.

[raid]

How about my Summar; it is marked with a Z! It may be too valuable to be ever sold.
[just joking here]

[FPjohn]

B or infinity - if the latter, is it a possible indication of value?
:)
yours
FPJ

[raid]

I am not joking here: My Summar has an incribed letter B at the same location. I took out my lens, and I used a magnifier.

Maybe it is the initial of the worker who put together the lens.

[MikeL]

Sigh, this thread just cost me 3 minutes of my life....... ;)

My summar from '36 has an A, and '39 has a 7.

[Matthew Allen]

My '34 has a 7 too, or at least what looks like a 7.

Matthew

[Austerby]

My Summar has a B and my Summitar an A. So there.

[Erik van Straten]

For a project I have in mind I have recently acquired an uncoated 5cm f2 Summar (217254 serial). There is a letter "A" engraved/stamped on the rear of the infinity lock. Is this usual and does it have any significance ?
It is simply an indication of the exact focal length of your lens. "A" means 52.2mm focal length.

Erik.

[L39UK]

The letters or numbers engraved on the rear of the infinity catch are there to indicate the exact focal length of the fitted lens cell. The focal length of the lens cell varied from the 50mm focal length on all Leitz early standard lenses and could range from approx. 49.5mm up to 52.5mm and this variance range is listed in some Leica manuals.If you look up the code letter or number engraved on the rear of the infinity catch and check it to the variance range codes it will tell you the exact focal length of your lens.
Regards,

[ChrisLivsey]

It is simply an indication of the exact focal length of your lens. "A" means 52.2mm focal length.

Erik.

I'd love to know the source of that information, for which thanks.

[raid]

I never heard about this fact. Thanks for the information. My lens is then not exactly 52.2mm.

[L39UK]

Refer to :-



Leica Collectors Guide by Dennis Laney (ISBN: 1874707006)

Regards,
William

[ChrisLivsey]

Refer to :-
Leica Collectors Guide by Dennis Laney (ISBN: 1874707006)

Regards,
William

Thanks. I've always avoided the "collectors" preferring to consider myself a "user" but this is a blurred line now. Time for a library addition methinks.

[John Shriver]

The pitch of the threads in the helical differs for each of these marks, and has to match the lens cell.

Very important to a repair person.

Also important in macro-photography to compute exact reproduction ratios based on lens extension.

My great Summar (324xxx) has what looks like a 7. My worthless dog Summar (346xxx) has a B, or perhaps an 8.

I'm surprised that any of the lenses used a letter.

[Artorius]

What does a 7 mean? That's what is on my 'cron.

[Al Kaplan]

At some point Leitz stopped making bunches of slightly different helicals (if they ever did) and started grinding a slight second cam into the brass ring that contacts the rangefinder's roller.

[Erik van Straten]

What does a 7 mean? That's what is on my 'cron.
1 means 50mm, 2 means 50.1mm and so on. 7 means 50.6mm.

Erik.

[Roger Hicks]

At some point Leitz stopped making bunches of slightly different helicals (if they ever did) and started grinding a slight second cam into the brass ring that contacts the rangefinder's roller.

Dear Al,

Indeed" 'if they ever did'. This is such a fantastically complicated solution (as compared with camming the lens, which is all I knew about) that I'd be amazed if ever they did.

I'd never heard of if -- though that doesn't necessarily mean much -- but from the point of view of inherent probability, it sounds deeply unlikely.

Cheers,

R.

[John Shriver]

Camming the rangefinder cam works on M mount lenses, where the indexing of the lens to the camera is predictable. It doesn't work very well on thread-mount lenses, since the rotational indexing of the lens to the camera is not highly predictable. The infinity mark could be anywhere between noon and 2 O'clock on the front of the camera. You can do it, but there's a compromise in the accuracy of the results.

I've certainly read authoritative materials stating that Elmar 50/3.5 lenses had various pitches of focusing helical threads.

The mapping of the code numbers and letters to actual focal length isn't very rational. There's some information on it in Puts's book, and they are all over the place.

[Roger Hicks]

Camming the rangefinder cam works on M mount lenses, where the indexing of the lens to the camera is predictable. It doesn't work very well on thread-mount lenses, since the rotational indexing of the lens to the camera is not highly predictable. The infinity mark could be anywhere between noon and 2 O'clock on the front of the camera. You can do it, but there's a compromise in the accuracy of the results.

I've certainly read authoritative materials stating that Elmar 50/3.5 lenses had various pitches of focusing helical threads.

The mapping of the code numbers and letters to actual focal length isn't very rational. There's some information on it in Puts's book, and they are all over the place.

Dear John,

Ah, that makes sense -- but I'm still surprised, because the degree of rotational focusing travel on most old lenses is quite large, and I don't think the variation in position would have been anything like as great (noon to 2 o'clock) when the cameras and lenses were new -- at least, not after the mid-30s when the faster lenses started to come in. After all, focal lengths other than 50mm are cammed, and must still depend on rotational positioning. Can you recall the sources?

Cheers,

Roger

[John Shriver]

The exact start point of the threads on the lens and mount isn't well-controlled. As they wear, the lenses screw on "further".

I think the source (for different pitch) was the post-war military report on the Leica factory. Can't find it at the moment.

[ChrisLivsey]

I think the source (for different pitch) was the post-war military report on the Leica factory. Can't find it at the moment.

This is the report, part 1 link to part 2 at the bottom:

http://www.angelfire.com/biz/Leica/page26.html