Re: Re: sunny 16

In a message dated 4/5/01 12:28:30 PM Central Daylight Time, egendron@vt.edu
writes:

> > > Using sunny/16, your exposure should be f/16
> >> @ 1/25 secs. There are about 10 stops separating f/16 from f/500,
> therefore
> >> for your camera, the uncorrected exposure time should be around 40
> >>secs (2^10
> > > * 1/25).
>
> I realize this is an elementary question, but here goes:
> Is the sunny-16 "setting" for a sunny day....
> a twenty-fifth of a second @ f-16? (most cameras only have a 30th,
> though it's not much difference)
> or is it a one-hundred-and-twenty-fifth of a second @ f-16?
> --
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> Edwin Gendron
> Virginia Tech
> Residential and Dining Programs Graphics
> 43 Owens Hall (0223)
> Blacksburg, Va. 24061
> (540)231-5398
> egendron@vt.edu
>
The sunny 16 rule implies that the f stop @ f 16 (The top number) over the
reciprocal of the film speed. Meaning that the bottom number in the equation
would be the nearest shutter speed that matches the speed of the film. I.E.:
ASA 100 film would correspond to a shutter speed of 1/100th of a second.
Since this isn't available on many cameras, (Yes, before someone writes to
tell me THEIR electronic gee whizz camera can set shutter speeds anywhere, I
said MOST cameras, meaning those that are being used manually... Otherwise,
why care about sunny 16?) the next nearest standard shutter speed would be
chosen, that usually being 1/125th of a second. If you were to use the same
sunny 16 rule with 400 ASA film, then the f stop would remain the same, f 16,
but the shutter speed would be set @ 1/400th of a sec, or the nearest speed
available. (1/500th on most manual cameras) Of course, this is just to give
one a starting point, and with the 100 ASA example given above, one could, of
course, use f 8 @ twice the shutter speed. Or f4@ four times the shutter
speed. And so on. This holds true pretty well for film... When using paper
and/or pinholes.... Well, all bets are off. Since the 1 in the fraction
1/125th or what ever is always the same, it is often simply implied, rather
than actually written out. So we often say 125th, meaning 1/125th. So it's
not 1/25th, not for the sunny 16 rule, unless, of course, you are using
Kodachrome! (ASA 24)
Hope this clears up any confusion.
Junkman
Received on Thu Apr 5 14:30:23 2001