metering with big_is EMF programmable AF confirm adapters

[randy_ramkissoon]

<p>Hi<br /> <br /> I purchased one of the new EMF auto focus (AF) adapters from big_is on eBay in May 2010 and recently have been noticing some weird issues with the light metering which I wanted to get some input on.<br /> <br /> <strong>Setup:</strong><br /> <br /> Contax Planar 50mm F1.7 on Fotodiox adapter mounted on a Canon 50D<br /> <br /> <strong>Problem:</strong><br /> <br /> When I am in AV or Manual mode and use the rear dial on the camera to match the f-stop on the aperture ring of the lens I notice this causes the light meter reading to move even though the aperture dial on the lens is not moving. The result is my pictures tend to get under/over exposed.<br /> <br /> <strong>Work around:</strong><br>

Don't change the f-stop in camera and leave at F1.8<br /> <br /> Technically I use the F-stop in camera so I know what settings I used to take the shot.<br /> <br /> <strong>Question:</strong><br /> <br /> Anyone else seeing this?</p>

[randy_ramkissoon]

<p>After getting some advise from a user at "photography on the net" I started to think that the reason for the under/over exposure was the exposure compensation (EC). Note that I normally shoot in manual (M).<br /> <br /> I decided to re-test with the following settings:<br /> <br /> -set lens aperture dial to F1.7<br /> -set camera to AV<br /> -verified in menu that exposure compensation is set to 0<br /> <br /> I then only turned the aperture dial on the camera body (dial on top of camera). I noticed as the f-stop increased from 1.8 to f4 the exposure time was increasing as if I was closing down the physical aperture. Of course the physical aperture never changed.</p>