Chuck Skinner wrote:
> > From: "JIm Linch" <[EMAIL PROTECTED]>
> > Jim, I can't speak to how often you would use the lens, but math tells us
> > the 1.4 will let in 92% more light than the 1.8, so it's nearly twice as
> > bright.
>
> How do you come up with 92%? I've done the math too, and come up with 62%,
> or just under 2/3 stop.
My sixth grade son did the math for me:
3.14 x (1/1.4) x (1/1.4) = 1.60
3.14 x (1/1.8) x (1/1.8) = 0.97
(1.60/0.97) X 100 = 165%
He also said that if we use pi to more than two decimal places, and
use the square root of 2 instead of 1.4 we'll get more accurate results.
He also told me to remember that "f-stop" is NOT aperture, but the
ratio of aperture to focal length.
-Nick
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