Archived posting to the Leica Users Group, 2001/01/06

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Subject: [Leica] Focus check (was Anybody use the 75 summilux on a .72x M6?
From: Christer Almqvist <>
Date: Sat, 6 Jan 2001 23:39:25 +0200
References: <>

(This is about optimizing telephoto lens/rangefinder combo for 
focusing at short distances)

>Chris. I did it myself - took a lot of time and involved groundglass,
>tripods, lots of film and strangely shaped screwdrivers (to get at the screws
>in the M3's focussing system). I would recommend that you find a good Leica
>technician and have him do it. Decide which body is the dedicated 75/1,4 and
>have it matched to the lens. I have seen these lenses work perfectly at all
>distances and I have seen them be off by a foot at close range. It does sound
>like a bit of a hassle, but once you get it rite, it is one of the truly
>awesome lenses ever made! I would love to find out if it is possible to make
>a mask for the 75/1,4 that would work on a M3 - even if I had to sacrifice
>the 90 or even the etched 50 mm frame - it would be a great combination. One
>day I will take a M3 viewfinder apart and see what can be done!
>Tom A

Thanks for the reply, Tom.

I just read an article about how to determine how to focus for IR 
film and I think I will use the method proposed there to check if my 
camera body and lens combo focuses correctly.

The method proposed (adapted to close range focusing) was:

- - set lens to shortest-but-one distance marked on the barrel
- - fix a piece of paper with a vertical line on a wall
- - place camera on tripod
- - adjust distance camera to wall so that vertical line is shown 
unbroken in finder
- - expose one frame
- - turn lens barrel (the one with distance scale) 2mm clockwise and expose
- - turn another 2mm and expose (repeat a few times)
- - go back to situation with unbroken line in finder and expose
- - repeat procedure above but turn barrel anti-clockwise

You may want to put the sticky portion of a post-it marker on the 
lens barrel with different coloured markings for the 2mm steps, and 
you may want to put post-it markers on the wall indicating how much 
you are off the distance marking which had been indicated to be 
correct. This helps greatly when reviewing the prints.

I will try this out with my skinny Tel-elmarit - a truly sharp lens, 
but not always with sharpness where I want it

- -- 
Christer Almqvist
D-20255 Hamburg, Germany and/or
F-50590 Regnéville-sur-Mer, France

In reply to: Message from (Re: [Leica] Anybody use the 75 summilux on a .72x M6?)