Hi!
1EV is 1s at f1 on 100 ISO film
2EV is 1s at f1.4, or 0.5s at f1
3EV is 1s at f2, or 0.5s at f1.4, or 0.25s at f1
4EV is 1s at f2.8 ....
And so on. The surface of the hole of lens is proportional to radius to
square, and the f stop number is proportional to radius that is why the
modulus of the series is 1.4 The modulus is equal 1.4 because with increase
of 1 EV you become 2 times more light. The EV number is a geometric series
with modulus equals SQRT(2)~1.4 by the f stop number.
Regards
Marcin
Henrik Dahl wrote:
> This is sort of embarrassing, I should know this. But the question is:
> how many EV's are there between F1.2 and 1.4 and 1.8 and 2 and 2.8?
> (Providing 1 full stop is 3 EV) Maybe someone who knows can just exchange
> the "and"'s for the correct number of EV's.
>
> Thanks
> Henrik Dahl
>
>
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