Archived posting to the Leica Users Group, 1998/08/14

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Subject: Re: [Leica] 75/1.4 versus 90/2.0
From: Mark Walberg <Walberg@simmons.swmed.edu>
Date: Fri, 14 Aug 1998 15:31:49 -0600

Raimo,   I think that depth of field is a function of magnification and of
f stop, but not of focal length.  In other words, an image made with the
same magnification and the same f stop will have the same depth of field
even if taken with different focal length lenses.  So, that implies that
for a particular magnification the f 1.4 lens will have less depth of field
than will the f 2 lens, ragardless of focal length. -Mark Walberg

>Shallow yes - but if you are talking about portrait at 1 m with the 90 mm
>lens you must compare it with portrait at 0.83 m with the 75 mm lens
>because of the lower magnification of the shorter lens. What do the tables
>say?
>Raimo