Notice how I easily changed the title to something meaningful so that folks
can tell what they're about to open from among a great onslaught of posts.
You digest people could be courteous if you wanted to be so. Just cut & past
the title of the post you're responding to into the "Subject" line of your
response. Since I have my mail system set to automatically delete posts with
subject containing "Digest", it's only when I'm checking my delete files
prior to permanent deletion that I'll see your posts.
EV Stop Marked
1.0 1.001.0
1.33 1.12
1.5 1.191.2
1.66 1.26
2.0 1.411.4
2.33 1.59
2.5 1.681.7
2.66 1.781.8
3.0 2.002.0
3.33 2.24
3.5 2.38
3.66 2.522.5
4.0 2.83
4.5 3.363.5
5.0 4.004.0
5.5 4.76
6.0 5.665.6
6.5 6.73
7.0 8.008.0
7.5 9.51
8.0 11.31 11.0
8.5 13.45
9.0 16.00 16.0
9.5 19.03
10.0 22.63 22.0
10.5 26.91
11.0 32.00 32.0
11.5 38.05
12.0 45.25 45.0
Regards,
Bob
"Going to war without France is like going deer hunting without an
accordion."
-- Jed Babbit (Former US Under-secretary of Defense)
From: "Gregory L. Hansen" <[EMAIL PROTECTED]>
> Paul Franklin Stregevsky said:
>
> > Chris Brogden <[EMAIL PROTECTED]> wrote:
> >
> > "I believe it's only a half-stop from 1.2 to 1.4."
> >
> > Here's how f/stops compare. I don't remember where I got these numbers.
I
> > may have derived them, so feel free to question them.
> >
> > f/1.2 is 0.45 stop faster than f/1.4
> > f/1.4 is 0.62 stop faster than f/1.8.
> > f/1.4 is 1.0 stop faster than f/2.0
> > f/2.0 is 0.67 stop faster than f/2.5.
> > f/2.5 is 0.33 stop faster than f/2.8.
> > f/2.8 is 0.7 stop faster than f/3.5.
> > f/3.5 is 0.3 stop faster than f/4.
> > f/4 is 0.25 stop faster than f/4.5.
> > f/4.5 is 0.67 stop faster than f/5.6.
>
> f/stop is the ratio of focus length to aperture diameter, and it all
> follows from there. The light hitting the film is inversely proportional
> to the square of f/stop (the aperture area), so to double the exposure
> you'd go, for instance, from f/1 to f/1.4, since (1.4/1)^2=2. And
> (2/1.4)^2=2, (2.8/2)^2=2, etc. That's why they chose those funny numbers
> to mark on the barrel.
>
> And if you can Taylor-expand the square root you can show that half way
> between two stops is close enough to half a stop. So going half a stop up
> from f/2 is technically f/2.45, but halfway between the numbers is f/2.40,
> which changes your exposure by 4%, which is not enough difference to
> matter when your exposure compensation goes by 33% or 50%. Going up by
> halves,
>
> f/1.0
> f/1.2
> f/1.4
> f/1.7
> f/2.0
> f/2.4
> f/2.8
> f/3.4
> f/4.0
> f/4.8
> f/5.6
>
> etc.
>
> I may not be a great photographer, but I know physics.
