Archived posting to the Leica Users Group, 1998/01/28

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Subject: Re: [Leica] Field of curvature good or bad?????
From: Eric Welch <>
Date: Wed, 28 Jan 1998 20:46:27 -0600

At 03:48 PM 1/28/98 -0500, you wrote:

>depth of field that allows us to shoot 3-D subjects with sharpness, NOT 
>CURVATURE OF FIELD!   A lens with high curvature of field will 
>certainly not improve sharpness at near distances in the corners and at 
>infinity in the center.  

There are always compromises in how lenes are designed. Notice that Leica
has been stressing how the new ASPH 35s have better flatness of field.
Leica used to let a little bit of curvature of field remain in some lenses
when there was a significant improvement in image quality somewhere else.
They didn't use it purposefully to make pictures look better. Of course the
PR department always played up things in the most positive terms.

It's just that some other corrections were more important. With new glass,
and new optical designs (and probably faster computers and better
software?) flatness of field can be achieved where in the past it would
have cost too much in other aberrations remaining.

At least, that's my figuring.

Eric Welch
St. Joseph, MO

Backups? We doan *NEED* no steenking baX%^~,VbKx NO CARRIER