Re: [Leica] Konica facts

[V8PWR@aol.com]

Dans un courrier dat=E9 du 09/05/01 16:45:06 Paris, Madrid (heure d'=E9t=E9)=
,=20
imxputs@ision.nl a =E9crit :

> There has been much discussion about the compatibility of Leica lenses=20
>  with the Hexar RF body. Most people, including all of the magazine=20
>  writers have assumed that the study of the bayonet mount (that is does=20
>  the Leica lens fit onto the Hexar bayonet) is sufficient to declare that=20
>  lenses and bodies can be safely intermixed. Problems have been=20
>  encountered and have been discussed as tolerance issues. As far as I=20
>  know, no one has extended the analysis to the most crucial part: the=20
>  back focus or the distance from bayonet flange to film plane. After=20
>  measuring it  and checking with the Konica people a most surprising fact=20
>  emerges.
>  The back focus of the Hexar RF is 28.00mm with a tolerance bandwidth of=20
>  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=20
>  the Konica ones (0.02 versus 0.06). Wonder why the Leica is expensive?=20
>  This small difference in tolerance is a hefty task in production=20
>  engineering.
>  Most importantly however is the conclusion that Leica lenses cannot be=20
>  used with any degree of confidence or performance on the Hexar. The back=20
>  focus difference of 0.2mm and that is much too large for even  a modest=20
>  demand on optical performance. It simply means that the leica lens=20
>  focusses 0.2 mm short of the film plane. A distance that is wide enough=20
>  to kill any idea that we are talking about precision optics or=20
>  engineering.
>  Nor can we use Hexar lenses on leica bodies, now the Hexar lenses will=20
>  focus behind the film plane by 0.2mm.
> =20
>  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=20
>  direction, which might bring the effective back focus to about 27.90 and=20
>  when stopping down or using a wide angle the difference is covered by=20
>  DoF.
>  The expectations about optical quality or the demands on the picture are=20
>  quite low.
>  The topics photographed are quite tolerant for uncritical focussing.
> =20
>  I find it remarkable that this topic has not been discussed as it is the=20
>  key to understanding the Hexar/leica compatibility issues.
> =20
> =20
>  Erwin
> =20

Anyone having bought a TRI-ELMER along with an Hexar RF can contact me
for selling his 3E at a low price .
Come on guys , let me deliver you from hell .=20

JO GOODTIMES -FRANCE/ AIRBORNE RADAR TECH / LIVE FREE OR DIE