Archived posting to the Leica Users Group, 2009/01/28

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Subject: [Leica] R lenses on any Digital body - exposure problem
From: douglas.sharp at gmx.de (Douglas Sharp)
Date: Wed Jan 28 14:44:15 2009
References: <28934303.1233176567512.JavaMail.root@mswamui-thinleaf.atl.sa.earthlink.net> <5EA8E333-8EE3-4123-91B4-6FA999397DE3@cox.net>

Hi,

although I posted this only a month or so ago, here it is again:

I never bothered to find out if it applies in manual metering mode - 
does any one know if that works correctly?

Bob Palmieri sent it to me OL in 2005

This is what Canon says about it:

The EOS 20D focusing screen is optimized for superior brightness at 
moderate apertures from about f/3.5 and smaller, compared to 
conventional ground glass designs. This makes the viewfinder image 
brighter and easier to focus at those moderate apertures, but the 
trade-off is that it passes disproportionately more light to the 
metering system. When a Canon EF lens is mounted to an EOS camera, a 
variable  exposure compensation factor (a program curve, not just a 
fixed compensation factor) for this phenomenon is fed through the system 
in order to provide correct metering for all apertures. However, when 
using a non-coupled manual diaphragm lens as you describe, no such 
communication takes place, so the responsibility for exposure 
compensation reverts to you. It's unnecessary to use an external meter. 
Instead, you can take a series of test shots at the working aperture(s) 
you plan to use, then analyze the test photos to determine the most 
desirable exposure compensation factor for each aperture. The 20D's auto 
exposure bracketing (AEB) function speeds up the process of taking the 
test photos, and you can use the Info palette in Photoshop to determine 
the most accurate exposure. If you can standardize on one particular 
aperture you plan to use (for maximum sharpness, desired depth of field, 
etc.), that will simplify the calibration process by eliminating the 
need for tests at other apertures.

Cheers
Douglas

Steve Barbour wrote:
>
> On Jan 28, 2009, at 2:02 PM, Wayne Serrano wrote:
>
>> Luggers,
>>
>> I am inclined or maybe I should say leaning towards a Canon (full 
>> frame) digital body to make use of the 28/2.8 current, 60/2.8 
>> current, 90/2.0 older, 100/2.0 Apo, and 180/2.8 APO lenses.  Which 
>> Canon body I have no idea....
>
>
> I have a Canon 5D Wayne...I have used a number of Leica R lenses on it...
>
> remember that there are issues re progressive overexposure as you 
> close down the diaphragm...
>
> I am not sure I understand why this is...help someone?
>
> it's fine if you shoot wide open,
>
> Steve
>>
>>
>> -----Original Message-----
>>> From: George Kase <gkase@ccfc.com>
>>> Sent: Jan 28, 2009 12:15 PM
>>> To: lug@leica-users.org
>>> Subject: [Leica] R lenses on any Digital body
>>>
>>> Wayne,
>>> Get any Canon EOS digital body ( I have a Digital Rebel XT) and
>>> Get an adapter for R to EOS mount and you're done. Cheap
>>> George
>>>
>>>
>>> _______________________________________________
>>> Leica Users Group.
>>> See http://leica-users.org/mailman/listinfo/lug for more information
>>
>>
>>
>>
>> _______________________________________________
>> Leica Users Group.
>> See http://leica-users.org/mailman/listinfo/lug for more information
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>

Replies: Reply from kididdoc at cox.net (Steve Barbour) ([Leica] R lenses on any Digital body - exposure problem)
In reply to: Message from wayneserrano at earthlink.net (Wayne Serrano) ([Leica] R lenses on any Digital body)
Message from kididdoc at cox.net (Steve Barbour) ([Leica] R lenses on any Digital body)