Archived posting to the Leica Users Group, 2012/10/12

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Subject: [Leica] turn around time for coding lens for digital M's
From: hopsternew at gmail.com (Geoff Hopkinson)
Date: Sat, 13 Oct 2012 09:51:42 +1000
References: <20599.17411.591734.750669@gargle.gargle.HOWL> <CAJ3Pgh6oy+qWndG1-22sNW3uaKR+jeqs6YO-vmK6+K=nsrRAcQ@mail.gmail.com> <CAE3QcF6q22UgtfbLrejFZa23o1EAshpecaPgg4nbRk0Rj2Jamw@mail.gmail.com> <BAEF0DB452924DFF9966D90D76311564@syneticfeba505> <CAE3QcF6qXRt-ozSbjfhcU1f7c7e3Eh9ko6HymsTP4RKoh4U2bA@mail.gmail.com> <A426AF03412E4FCCA5665ECC12FBBAA0@syneticfeba505> <6262B0B0-77EC-4E8A-A51F-4B55CD534073@acm.org>

More than one log you threw on the fire, Herbert ;-)
Yes there really are lasers and computer analysis involved!. I've watched
the rangefinder adjustment done. Mere mortals don't get invited into their
lens assembly clean rooms though.

DP Review posted an informative article in 2009 you might like to look at.
http://www.dpreview.com/articles/leicafactory2009/
Look at the sensor positioning adjustment in the body and the rangefinder
adjustment.

Digital M's are not only more critical (due to the effectively zero depth
of the sensor) with lens adjustment but people can readily see any (human
or equipment) error at high magnification on their computer monitor

Cheers,
Geoff
http://www.pbase.com/hoppyman



On 12 October 2012 15:51, Herbert Kanner <kanner at acm.org> wrote:

> I'm gonna add some fuel to this fire. Maybe there is some technical
> witchcraft going on that I don't understand, or maybe some of you guys are
> just plain superstitious and Leica is talking a lot of impressive bullshit
> about lasers and suchlike.
>
> So here is the understanding I've had for years as to how Leica worked
> interchangeable lenses with a rangefinder mechanism.
> 1. The rangefinder was designed to work with a 50mm lens in that the as
> the lens unit moved to and from the film plane, the real end of the lens
> container pressed against a roller on a lever that actuated the rangefinder
> mechanism. Other lenses used a pair of threads (the technical term being
> differential threads) so that as the lens focussed (with greater motions if
> the focal length was more than 50mm and lesser motion if less than 50mm)
> the rear cylinder would move the same distance as that of a 50mm lens. With
> that kind of system, the only adjustment that would be possible would be
> setting the infinity stop and setting the distance marking ring to agree.
>
> Also, there is absolutely no reason for a digital camera to have any
> different focussing problems than a film camera. It just that the focus
> might be a bit more accurate since the sensor is rigid and there is always
> the possibility, despite a pressure plate, that the film is not exactly in
> a plane.
>
> Herbert Kanner
> kanner at acm.org
> 650-326-8204
>
> Question authority and the authorities will question you.
>
>
>
>
>


Replies: Reply from kanner at acm.org (Herbert Kanner) ([Leica] turn around time for coding lens for digital M's)
In reply to: Message from hartzell at alerce.com (George Hartzell) ([Leica] turn around time for coding lens for digital M's)
Message from roark.paul at gmail.com (Paul Roark) ([Leica] turn around time for coding lens for digital M's)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] turn around time for coding lens for digital M's)
Message from tedgrant at shaw.ca (tedgrant at shaw.ca) ([Leica] turn around time for coding lens for digital M's)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] turn around time for coding lens for digital M's)
Message from tedgrant at shaw.ca (tedgrant at shaw.ca) ([Leica] turn around time for coding lens for digital M's)
Message from kanner at acm.org (Herbert Kanner) ([Leica] turn around time for coding lens for digital M's)