What's up with Leica lens minimum focus markings?

[everyXnewXday]

Couple questions:

1. What is the reference point for the distance markings? The film plane or the lens mount?

2. Where should I line up the markings for checking rangefinder alignment? I.e., is it the leading edge of the number? The middle?

I'm confused because on my 50mm Summilux E43 (1 meter minimum) when I set the focus ring all the way to the near focus stop it moves past the "1" on the focus scale but the distance to the film plane seems to be 1 meter and the rangefinder lines up perfectly. When I place the camera by measuring 1 meter from the subject to the lens mount and align the rangefinder it ends up being exactly on the "1". ??

 

[mooge]

1. Film plane, I'd imagine? since that's the only real reference point. But what do I know; I'm just some guy on the internet.

2. To check rangefinder alignment you should really be using a ground glass and magnifier on the film rails. (I use an old focusing screen from a Spotmatic, and my nokton 35 as a magnifier. Put camera on tripod, hold shutter open with cable release, tape the ground glass to the film rails, focus with that, check RF to see if it agrees...)

I don't think the distance markings on the lens are meant to be really precise; I don't think it's a great idea to calibrate your RF with them...

cheers.

 

[michaelwj]

Film plane. The M6 and maybe from M4-2 onwards have a mark (-0-) under the advance lever.
The makings should be spot on at infinity, but they get less accurate as you approach minimum focus distance (or so I am told - I think Andy (adan on LUF) mentioned something... he seems to know stuff). Either way, the same thing happens on my 1.4/35 pre asph.

 

[Dwig]

#1 - The industry standard has always been to use the film plane.

#2 - The markings on Leica's lenses are rather accurate, as such things go, but are nowhere near accurate enough for any form of RF adjustment.