Quote Originally Posted by StoneNYC View Post
The eyepiece cover has nothing to do with metering, it's that with long exposures, you sometimes have light leak THROUGH THE VIEWFINDER so you need to cover it so that when the mirror is up and shutter is open, the film doesn't get unwanted stray light from the viewfinder.


~Stone

The Noteworthy Ones - Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1 / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic

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Then why do my meters give different readings, depending upon whether or not light is getting in through the viewfinder?

I've checked this myself and assure you that it is indeed, at least for some cameras, particularly automatic everything models, a metering issue.