Hi Bill,
In addition to what the others have said, I keep a spare card which contains a variety of footage I know is exactly spot-on exposure-wise in the camera bag (it’s just an SD card in an adapter, but it works). I regularly play this through the EX3 and make any adjustments necessary to the viewfinder controls. I keep my viewfinder controls taped up so they can’t accidentally get twiddled. I find this ‘calibration footage’ really helpful – probably not very scientific, but it works for me.
Martin Phillips Freelance Cameraman / Producer / Editor
Chesham, Buckinghamshire, UK. http://www.videodvdmaker.co.uk