Archived posting to the Leica Users Group, 2006/06/17

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Subject: [Leica] Re: Full frame problems
From: don.dory at gmail.com (Don Dory)
Date: Sat Jun 17 05:43:30 2006
References: <200606160301.k5G31HGt020575@server1.waverley.reid.org> <3cd82cd6d7c5b33c6001b44d5a793dc7@optonline.net> <p06230935c0b94cdc927c@10.1.16.131>

Henning,
Leica told us several years ago that the process of microlenses made a dM
possible.  That could be what is driving the bar code as the collection
pattern of the lenses could only be optimized for one pattern of light
coming off a lens.  The bar code would let the camera processor modify this
transparently to the user.

I am still at a loss as to why the 135 APO can not be adapted but the 135
F2.8 can.  The spectacles would help with focusing accuracy, but they can do
the 75 Summilux which has an even narrower dof so it doesn't have anything
to do with the rangefinder.  The lens itself has the optics well forward of
the mount so it is already teleocentric.

Don
don.dory@gmail.com


On 6/17/06, Henning Wulff <henningw@archiphoto.com> wrote:
>
> At 11:41 AM -0400 6/16/06, Lawrence Zeitlin wrote:
> >The grazing angle of a 50 mm lens (back focus about 30 mm) is about
> >33 degrees at the corners of the image frame. The Kodak KAI-110000
> >sensor, the one that Leica will probably use, requires an angle no
> >greater than 15 degrees. A strong planoconcave correction plate in
> >contact with the full sized sensor might be the least expensive but
> >it would require considerable design work and would not work
> >optimally with all lenses. The plate would have to deflect light to
> >the vertical by 18 to 20 degrees at the corners decreasing to zero
> >degrees at the center. For lenses shorter than 50 mm, the corner
> >deflection angle would have to be greater, longer lenses would
> >require less deflection. A fixed correction plate would work best
> >for only one focal length. One suggestion was to supply alternate
> >plates for specific lens ranges, another was to use a single plate
> >and correct for light fall off by software, the frame actuator or
> >lens coding triggering the right software mode. An alternative
> >suggestion to the planoconcave correction plate is a fresnel lens
> >with groove artifacts removed by software. The suggestion proposed
> >in a Leica press release was to use individual micro lenses over
> >each of the image wells in the sensor, most probably molded into a
> >single pastic overlay. This is a modification of the fresnel lens
> >method.
> >
> >Which approach will Leica use? I'm taking bets now.
> >
> >Larry Z
>
> Since Stefan Daniels said that Leica is going to use microlenses,
> I'll take that bet now. :-)
>
> --
>    *            Henning J. Wulff
>   /|\      Wulff Photography & Design
> /###\   mailto:henningw@archiphoto.com
> |[ ]|     http://www.archiphoto.com
>
> _______________________________________________
> Leica Users Group.
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>

Replies: Reply from leicaluvr at comcast.net (Tom Schofield) ([Leica] Re: Full frame problems)
In reply to: Message from lrzeitlin at optonline.net (Lawrence Zeitlin) ([Leica] Re: Full frame problems)