To start off, I'm cognizant of what metering is (this isn't an aperature and shutter thread). What I can't figure out is how it works. What reads the metering image on a DSLR? Because your image never makes it to the CCD. You can understand, this became an important question when I was looking at the process of putting a non CPU lens on my nikon DSLR, and I began to wonder.. What information does a lens exchange with the body? ( As a consequence: ) Why doesn't metering work with a non CPU lens? Best Regards, Scott D70s PS: it won't even show the exposure level.