Archived posting to the Leica Users Group, 2000/08/09

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Subject: [Leica] Sharpness and depth-of-field
From: Pascal <>
Date: Wed, 9 Aug 2000 10:03:10 +0200

A friend of mine and longstanding Leica user has the following 
interesting question on sharpness and depth-of-field.

A look at the depth-of-field tables for Leica lenses gives some 
surprising figures. When the lens is turned to the *infinity* position 
this gives the following:

- - 90mm lens: f/2.8: sharp image as from 86.90 meters, at f/4.0: from 
60.80m, at f/5.6: from 43.40m.
- - 135mm lens: f/2.8: sharp image as from 195.40 meters, at f/4.0: from 
136.80 m, at f/5.6: from 97.60 m.
- - 180mm lens: f/2.8: sharp image as from 343.14 meters, at f/4.0: from 
242.69m, at f/5.6: from 171.67m.
- - 280mm lens: f/2.8: sharp image as from 835.00 meters, at f/4.0: from 
591.00m, at f/5.6: from 418.00m.

These are amazing figures! As atmospheric haze also starts to have an 
effect as from about 300 meters I would say, how on earth can we get 
sharp pictures of subjects at some distance? I presume that no manual or 
automatic focussing aid can differentiate between infinity and 87m for 
the 90mm, 195m for the 135mm, 343m for the 180mm and 835m (!) for the 
With the M camera (even with the M3) how can one see the difference 
between 87m and infinity with the 90mm and 195m (!) and infinity with the 

It would be most instructive to have the LUG's opinion, and also Erwin 
Puts', on this matter.
Thank you.

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