serial # scratched inside lens barrel

[david_werbeloff1]

Hi All: I'm considering buying a 90mm Elmarit. I was surprised not to find the

lens serial number scratched inside the lens barrel when I unscrewed the optical

unit. On both my 135mm Elmar and DR Summicron this has been done. The DR

Summicron even has the actual focal length scratched inside the barrel along

with the serial number. Should I be concerned that the lens unit and barrel are

not a matched set? I'll be running a roll of film through the camera to check

that the rangefinder cam is coupling correctly and also for any strange

abnormalities in the images.

 

Anything else I should watch for? Under the oblique light from a flashlight I

see a cleaning mark in the center of the front element, otherwise the glass is

beautifully clear; no signs of fungus or separation.

 

Best, David

[ronald_moravec1]

Done at factory to ensure head and mount remain a matched set. Only the last 4 digits are

engraved inside the barrel.

[mark_theken]

I have also seen the serial number on a paper sticker attached inside the lens mount so the missing "scratched" serial number is not a 100% certainty of a "mismatch". Probably it is best to shoot a test film with camera on a tripod and check the film for sharpness with a loupe. Lens can also be recalibrated by a competent repair person.

[david_werbeloff1]

Hi Ronald and Mark:

 

Thanks for your replies. After looking inside the lens barrel again, this time with a magnifying glass, I found the last 3 digits of the serial number scratched there along with what looks like the tech's initials. I feel much better now that the lens is good. There are no signs that any unqualified hands have messed with the lens, which is also reassuring. Will still run a film through.

 

Best,

David

[john_shriver]

I think in some of mine, it's just pencil, not even scratched. My Elmar 90/4 has red pencil, the Hektor 135/4.5 graphite pencil.

 

David is right to be concerned. If a lens is in a mount for a different focal length group, it will never focus accurately at close distances. Correcting the infinity shimming can be done with such a "mutt", but the thread pitch of the helicals depends on the focal length of the lens. (Although some Leica lenses don't even have infinity shims, perhaps they filed the mount to length?) You cannot recalibrate for the wrong helical thread pitch, this is a "select at test" operation.