RE: [Leica] Konica facts

[Paul Chefurka <Paul_Chefurka@pmc-sierra.com>]

Not to steal a march on Ted or anything, but you guys are making way too much of a theoretical incompatibility that may or may not exist.  The proof is in the shooting as always, and since my shots look sharp, I've decided that they probably are sharp.  In all the discussions about the Hexar here and elsewhere, I've heard very few (as in no) complaints about systematically unsharp photos.  Other problems yes, but not general unsharpness or bad focus.

I think it's a bit premature to start hyperventilating about this.  Sounds like y'all have gotten into Kyle's medicine cabinet again.

Paul

- -----Original Message-----
From: Dan States [mailto:dstate1@hotmail.com]
Sent: Wednesday, May 09, 2001 2:29 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: Re: [Leica] Konica facts


An even better question would be:WHY THE HELL WOULD KONICA DO THIS?!?

Despite their own statements they clearly intended the HexarRF to be 
considered compatable with Leica M mount lenses, or they would have made 
their own damned mount and avoided the subject entirely.

They have foisted a package on the public under the unspoken pretext of a 
compatability that is just not there.  Shame shame.

Dan States
Madison WI

>
>There has been much discussion about the compatibility of Leica lenses
>with the Hexar RF body. Most people, including all of the magazine
>writers have assumed that the study of the bayonet mount (that is does
>the Leica lens fit onto the Hexar bayonet) is sufficient to declare that
>lenses and bodies can be safely intermixed. Problems have been
>encountered and have been discussed as tolerance issues. As far as I
>know, no one has extended the analysis to the most crucial part: the
>back focus or the distance from bayonet flange to film plane. After
>measuring it  and checking with the Konica people a most surprising fact
>emerges.
>The back focus of the Hexar RF is 28.00mm with a tolerance bandwidth of
>0.06mm!
>The Leica data are: 27.80mm with a max tolerance of 0.02mm.
>The first observation is this. Leica tolerances are 3 times as narrow as
>the Konica ones (0.02 versus 0.06). Wonder why the Leica is expensive?
>This small difference in tolerance is a hefty task in production
>engineering.
>Most importantly however is the conclusion that Leica lenses cannot be
>used with any degree of confidence or performance on the Hexar. The back
>focus difference of 0.2mm and that is much too large for even  a modest
>demand on optical performance. It simply means that the leica lens
>focusses 0.2 mm short of the film plane. A distance that is wide enough
>to kill any idea that we are talking about precision optics or
>engineering.
>Nor can we use Hexar lenses on leica bodies, now the Hexar lenses will
>focus behind the film plane by 0.2mm.
>
>Why then are many users of Hexar bodies with Leica lenses happy?
>Pick anyone of these explanations.
>One  happens to have a Hexar where the max tolerance all are in one
>direction, which might bring the effective back focus to about 27.90 and
>when stopping down or using a wide angle the difference is covered by
>DoF.
>The expectations about optical quality or the demands on the picture are
>quite low.
>The topics photographed are quite tolerant for uncritical focussing.
>
>I find it remarkable that this topic has not been discussed as it is the
>key to understanding the Hexar/leica compatibility issues.
>
>
>Erwin

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