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: kididdoc at cox.net (Steve Barbour)
Date: Wed Jan 28 16:23:01 2009
References: <28934303.1233176567512.JavaMail.root@mswamui-thinleaf.atl.sa.earthlink.net> <5EA8E333-8EE3-4123-91B4-6FA999397DE3@cox.net> <4980DFAA.5090609@gmx.de>

On Jan 28, 2009, at 3:43 PM, Douglas Sharp wrote:

> 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.

thanks Douglas, so with Canon, aside from shooting wide open, you must  
calibrate/compensate, and  that is  a minor pita...


Steve


>
>
> 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
>>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information


Replies: Reply from lug at steveunsworth.co.uk (Steve Unsworth) ([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)
Message from douglas.sharp at gmx.de (Douglas Sharp) ([Leica] R lenses on any Digital body - exposure problem)