Archived posting to the Leica Users Group, 2000/06/05

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Subject: Re: [Leica] more d.o.f. with asph?
From: "Henning J. Wulff" <>
Date: Mon, 5 Jun 2000 00:01:22 -0700

At 12:40 AM +0100 6/5/00, Christer Almqvist wrote:
>Looking at some 16x b+w enlargements from shots I made recently in the
>middle of the night in Dublin's Temple Bar district with my 35 mm Summicron
>asph fully open using HP5 pushed to 800 in Rodinal 1+25 for 10 mins........
>..... I get the impression that the depth of field with the asph lens is
>much wider (or larger or deeper or whatever) than with the comparable
>pre-asph lens. I try to explain this to myself in the following way: if
>d.o.f. is defined as the area which the lens can render on film meeting
>certain resolution criteria, then a lens with a higher resolution than
>another lens (at the same fstop) will automatically have a wider d.o.f.
>Is this the correct explanation, or is there another one,  or am I just
>trying to find a justification for the lens upgrade?
>BTW, the Summicron asph is remarkable, sharp as it is fully open. The bokeh
>is  sweet as honey. I do not miss having an extra stop, I'll use the $ 1000
>I saved getting a Summicron rather than a Summilux to upgrade one of my
>other lenses to asph as soon as I can find a demonstrator will full
>Christer Almqvist
>D-20255 Hamburg, Germany and/or
>F-50590 Regnéville-sur-Mer, France

There is a certain truth to this, as the additional spherical aberration
that the pre-ASPH Summicron has makes particularly the out-of-focus areas
appear softer, broader (and smoother) than the ASPH will render them. The
Summicron ASPH still has smooth out-of-focus areas, but in a more
'controlled' and tighter manner and not in quite the 'dreamy smooth' way
that the previous lens had.

   *            Henning J. Wulff
  /|\      Wulff Photography & Design
 |[ ]|

Replies: Reply from Ebert Steele <> (Re: [Leica] spherical aberrations was more d.o.f. with asph?)