Re: Paper Film Means Long Exposure?

----- Original Message -----
From: "Bob & Jennifer" <jenbob@intrepid.net>

> Seems like everyone agrees that the paper is ISO 6.
>
> Seems like that is an approximate f stop of f/186

> Can someone give me a recommended starting point for full sun?

f/186 is 7 stops away from f/16

For full sun, exposure should be f/16 and 1/ISO secs, if you were using
f/16 you should expose paper for 1/6 secs. Since you are not using f/16 but
f/186 and that is 7 stops smaller than f/16 you'll have to double the time 7
times, which is the same as multiplying the time buy 2 to the power of 7,
which is the same as multiplying the time by 2x2x2x2x2x2x2, so your time for
paper exposed with f/186 under full sun should be (1/6) x 128 = 128/6 =
21.33 seconds. Then there is reciprocity corrections, you could use a table
that I have here:
http://members.home.net/penate/pinsize.htm

BTW, f/186 is just 3 stops away from f/64 so the multiplier is 2x2x2 = 8
(around 8.5 if you use all the decimals in the math calculations, and 8.5 is
close enough to 8.7, anyway)

Guillermo
Received on Thu Jan 11 15:16:10 2001