Quote Originally Posted by noparking View Post
I assume it's calibrated to match the ISO sensitivity of 100 that I had the camera (an light meter) set to.
There are at least two different ISO specifications for light sensitivity - one for film and one for digital sensors.

If you want to see if there is a useful correspondence between how the metering system in the E-P1 reads light and how your Luna-Pro SBC reads light, you need to take reflected light readings with each of them from something like a large, evenly lit, monotone wall that has a consistent colour and reflectivity throughout.

Make sure that the angle of acceptance of the Luna-Pro SBC and the E-P1 are approximately the same, and that both are pointed at approximately the same point on the wall, and in the same direction.

Make sure you are metering manually with the E-P1.

If possible, try this at a number of different light levels.

The readings may either match, or if they are different, the difference may be constant. If so, that will tell you how to use one meter and compensate to obtain the same results as the other.

If the difference is not constant, you won't be able to use these interchangeably. In that case, most likely the metering in the E-P1 includes a built in adjustment to take into account the peculiarities of that system.