Originally posted by Steve Beswick I think there may be some confusion regarding my inital post, so please allow me to attempt clarification. My question is this: do lenses that report focal length info to the camera update the info based upon zoom changes. For example, if I put my autofocus Sigma on the camera it is usually set to around 50mm. When I rotate it to 80mm does the lens say to the camera "I'm at 80mm now", or does it leave the camera thinking it's at 50mm?
Why don't you just put your autofocus Sigma onto your camera, take a few pictures and check the EXIF.
Then you'll know what your equipment is doing.
It's really hard to predict how third party equipment is going to work, as sometimes it is inexplicably crippled due to poor implementation of technology.
I believe one poster mentioned that Pentax F lenses and later report focal length to the camera, I know my 60-250 reports focal length as it is zoomed.
Perhaps it's time to turn off the computer and pick up the camera and see what your equipment is doing.