RE: [Leica] Re: Konica facts

[Henning Wulff <henningw@archiphoto.com>]

At 12:09 PM -0700 5/9/01, Paul Chefurka wrote:
>On this issue of back focus - it's my understanding that wide-angle 
>lenses are more critical for back focus than long lenses, rather 
>than less critical.  Something about depth of field and depth of 
>focus being inversely related or something.  Can anyone enlighten me?
>
>Paul

It's not that wide angles are more critical; the f/stop is all that 
matters. However, while a 0.2mm increase in the back focus causes a 
35mm lens to focus at 6m instead of infinity, the same back focus 
error will cause a 135mm lens to focus at 90m instead of infinity. If 
they were used at the same aperture, one shot would look as fuzzy as 
the other.

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    *            Henning J. Wulff
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