Please bear with me I've only been doing this photography thing for 52 years now. I have a simple question: I have a Gossen Digisix which reads smack on, with a friends Minolta (something or other) meter as well as my Gossen luna Pro etc. taking a reflected light reading from a 18% grey card or general light reading. AS well I have a Nikon F2, F3HP, a Nikon F4 and a Hasselblad with a PME 5 meter. All these cameras read better than 1/3 stop of one another from a 18% grey card or general light reading. My camera meters read almost exactly 1 stop lower than the handheld light meters from the same scene. Now what?