[LRflex] Re: New Year and new camera - exposure problem


On Dec 28, 2008, at 10:30 AM, Douglas Sharp wrote:


I last posted this in 2005 after  Bob Palmieri had sent it to me OL

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...


but I don't believe this happens with the Oly E3...


Steve



Cheers
Douglas



Steve Barbour wrote:


On Dec 27, 2008, at 9:31 PM, Aram Langhans wrote:
Stop down metering does not work as "advertised" The further you stop down, the more overexposed the photo becomes. I am talking about in Aperture metering mode or in Manual metering mode. The meter lies. You need to compensate the more you stop down. +/- override in A mode, or just ignore the meter in manual mode. Focus and meter wide open, then if you stop down 3 stops, just do the same for the shutter (slow it down) and ignore the fact that the meter tells you that you are grossly underexposed. 



My experience is the same.
Why does this occur on the Canon, my case the 5D, but not with the Olympus E3, and Leica R lenses? 

Any ideas?  Experiences?  Is there a way to "fix" this problem?




Steve

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thanks,  Steve








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