Luna-Pro sbc light meter compared with Olympus E-P1 for accuracy
I recently purchased an old Gossen Luna-Pro sbc light meter. It seems in excellent condition with case and manual. The internal battery test indicates as good; and the meter is correctly zeroed with the battery removed. When I went to check its accuracy by comparing exposure readings with my Olympus E-P1 the exposure values reported by the light meter in reflective mode (i.e., spherical diffuser moved to the side) are way off. (I have to adjust the exposure factor from 1 to 4 to get the Goessen reflective value to match the E-P1's). Here's the odd part, when the Gossen is in incident mode (i.e., spherical diffiuser is inline with light sensor) the exposure reading of the Gossen matches ~ that of the E-P1.
The E-P1 is giving a reflective light reading; and the fact that the light meter exposure value in incident light mode matches the E-P1 is purely coincidence, correct? The light meter readings should be close to the E-P1's reading when in refective mode, correct? If I'm to use this meter as-is, I'll need to use it in its incident reading mode as a reflective light meter as a workaround?