Re: [Leica] Konica facts

["Dan States" <dstate1@hotmail.com>]

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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