After watching Tony's YouTube video on DxOMark, I was looking at DxOMark's ISO Sensitivity measurements of my Olympus OM-D EM-5 II. I noticed that the measured ISO is more than a full stop less than the manufacturer ISO. This explains why my friend, shooting a Nikon, had such different exposure settings than me even though we were photographing the same things.
Is there someway to calibrate the camera to be closer to the actual ISO? For example, I would want ISO 200 to be ISO 100. Or do I just have to know that when it says ISO 200, it's really ISO 100.
When you're doing things like using the sunny 16 rule, it doesn't quite work: 200 ISO, f/16, 1/200 sec would be underexposed because it really should be f/16, 1/100 sec. I haven't field tested this yet. It's nighttime.