Aim your EP1 at an 18% grey card that fills the view, and note the reading. Now, in the same light, aim your Gossen meter in reflected metering mode at the same grey card and note its reading. Now, in the same light, aim the incident light hemisphere of the Gossen meter toward the camera lens position, and note its reading. If the three are not within about 0.66EV of each other, one of the meters (likely the Gossen) is in need of calibration.
The 'digital calibration' vs. 'film calibration' is a bunch of hooey!!!
I can aim a Minolta one-degree flashmeter at a grey card, I can aim my Canon digital camera at a grey card, I can aim my Olympus OM-1 at the same grey card, and they all agree with my Minolta Autometer Vf in incident mode. I just did it, to make sure I am not making false claims!
I have written previously my assertion is based on extensive tests carried out by the U.K Professional Photography Magazine using a Minolta Autometer Vf with various DSLRs and types of film, the tests were extensive and the conclusion irrefutable.
The 'digital calibration' vs. 'film calibration' is a bunch of hooey!!!, and they used to believe the World was flat.