Archived posting to the Leica Users Group, 1997/07/02

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Subject: Re: R8 and Contax AF !!
From: "Lucien_vD@compuserve.com" <Lucien_vD@compuserve.com>
Date: Wed, 2 Jul 1997 08:53:20 -0400

Martin Tai wrote:

>On the contrary, the only way to get best optical performance
>is UNIT FOCUSING, ie,  move the lens as a whole. The internal focusing

Kari Eloranta wrote

>I'm quite sure this is false. For example macros are specialized
>designs for short distances that can be outperformed at infinity.
>And obviously viceversa. Macros don't exist only because some people
>like to get real close, like two inches. Their imageplane flatness etc.
>characteristics etc. are already superior at half a meter which is
>within the distance scale of a SLR normal lens. If your argument would
>be true, a good, fixed, optical formula would work uniformly well at
>all distances (that the lens focuses) which is not true.

>I'm not saying that the Contax design is bad, not at all. In particular
>it allows the user to switch off the AF and do the focusing manually
>with floating elements AND with a tight lens. But to me it seems that
>this type of AF in actual use sacrifices some of the optical potential
>of the lens. =


I fully support this.
I don't need AF in the R8 if it work in the Contax way.
I will prefer then only a good focus confirmation and pay (much) less.

Lucien
BELGIUM