film speed question?

hi
say your film speed with delta 100 developed in pmk 50 and you change just the spot meter you use , and the difference between the readings you get between the old spot meter and the new is 1 EV the new one reading 1 ev lower. sand thats all you change . should not the film speed now be 100 again? that what i did and the film speed test still shows i need to rate the film at 50. help what did i do wrong ?
mitch

I'm not sure I completely understand your question, but if you change the ISO setting on your spotmeter from 100 to 50, then you are giving your film 1 stop more exposure than you would if you exposed at the rated ISO speed for the film.

There is still the same amount of light in the scene with the same contrast, correct? Just use the new meter the way it is and see what you get. Set things based on the new meter. If there is a difference between meters, will the picture really care if you called it ev 1 or ev 5, as long as the meter reads the light as zone 5? tim