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.