[wiltw]

The light meters in digital cameras are designed for that cameras individual sensor not film , so I.S.O 100 on a digital camera isn't the same as 100 I.S.O on a hand held separate light meter and film which is why the readings don't agree, if you want to use a reflected/incidental hand held meter use film.

OMG, this is a lot of misleading information. If it were true, why would my Minolta Spotmeter F give me identical readings as my Canon dSLR, when both are aimed at the same 18% grey card and set to the same ISO value?!?!?!

In fact, using my Minolta Autometer Vf in incident mode, its reading agrees with the two reflected light meters mentioned above, too.

And exposures are fully satisfactory if I am shooting with my medium format film color transparencies or my dSLR...I do not need to compensate one vs. the other, to deviate from the meter suggestion, which would be necessary if the digital ISO value were not the same as film ISO.