Re: f64,f90,f128?...

Andrew,

f/stops progress by a factor of 1.414 which is the square root of 2, therefore,
the numerical value of f/stops double every other stop. If we start at f/11 (we
could have started with any f/stop), the next one is f/16, since they double
every other stop, the progression would go like this:

1 (half 2)
1.4 (half 2.8
2 (half 4)
2.8 (half 5.6)
4 (half 8)
5.6 (half 11 or so!!)
8 (half 16)
11 ---------->known starting consecutive f/stops
16 ---------->known starting consecutive f/stops
22 (double 11)
32 (double 16)
45 (double 22...or so!!)
64 (double 32)
90 (double 45)
128 (double 64)
180 (double 90)
256 (double 128)
.....add infinitum

So, if you know 2 consecutive full f/stops values, you can find out any other
full f/stop in the progression.

Guillermo

----- Original Message -----
From: "Andrew Amundsen" <andy@tcinternet.net>

> Can anyone help? What's the proper progression of f-stops above f90? Is f128
> next and tell a couple more if you have the info at your fingertips.
>
> I've picked up a Finney Pinhole Bodycap for my Leica M. It's listed as a
> 30mm, approx. f128 and my Minolta meter goes to f90. So is f128 the next
> f-stop in the natural progression of reciprocity? Twice as small? If not
> someone please correct me!
>
> Thanks for the help, Andrew Amundsen
Received on Sat Oct 12 20:44:36 2002