Velocity Reviews > Formula?

Formula?

Jim
Guest
Posts: n/a

 01-25-2004

My niece is taking a Digital photography class. The teacher is trying to
teach the students how to figure out the f-stop without using a meter. He is
giving them the lighting condition and the film ISO. (I know he is teaching
them film photography first!) Is there a easy formula for this? My niece
says the teacher ran through it so quickly she does not understand how to do
it. Thanks for any help

Webrosita
Guest
Posts: n/a

 01-25-2004
>"Jim" http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:

>My niece is taking a Digital photography class. The teacher is trying to
>teach the students how to figure out the f-stop without using a meter

If I remember correctly it is called the Sunny 16 Rule and it used to be
included in the print insert for all Kodak film. I did a Google search and came
out with this url:

http://www.camerareview.com/templates/sunny16.cfm

KBob
Guest
Posts: n/a

 01-25-2004
On Sun, 25 Jan 2004 12:53:00 GMT, "Jim" <(E-Mail Removed)> wrote:

>
>My niece is taking a Digital photography class. The teacher is trying to
>teach the students how to figure out the f-stop without using a meter. He is
>giving them the lighting condition and the film ISO. (I know he is teaching
>them film photography first!) Is there a easy formula for this? My niece
>says the teacher ran through it so quickly she does not understand how to do
>it. Thanks for any help
>

She's better off if left to work this out for herself--otherwise, how
will she learn this? In any case the basic formula is:

Film sensitivity X Illuminance = Aperture X Exposure Time

and for convenience these quantities are usually expressed in terms of
their Log2 values (and choosing a suitable starting value). When this
is done, the formula becomes:

Exposure Value = Film Value + Brightness Value
-or alternatively-
Exposure Value = Aperture Value + Time Value

where
Exposure Value (EV) is 0 at T=1 sec, Aperture (f/#)=1, and ASA=3

To simplify things the "Sunny 16" method can often be used, and I
suspect the "lighting condition" you refer to may be covered by this.
For example:

Shutter setting = 1/ISO at f/16 for midday sun

where "midday sun" might be assumed to be about 10,000 foot candles.
Add a couple stops for shade, subtract a stop or two for sand or snow,
and there you have it!

JC Dill
Guest
Posts: n/a

 02-05-2004
On Sun, 25 Jan 2004 14:41:16 GMT, KBob <(E-Mail Removed)> wrote:

>To simplify things the "Sunny 16" method can often be used, and I
>suspect the "lighting condition" you refer to may be covered by this.
>For example:
>
> Shutter setting = 1/ISO at f/16 for midday sun
>
>where "midday sun" might be assumed to be about 10,000 foot candles.
>Add a couple stops for shade, subtract a stop or two for sand or snow,
>and there you have it!

1/400 shutter with 400 iso at f16 = 1/400 shutter at 200 iso at f 11,
= 1/400 shutter at 100 iso at f8, = 1/800 shutter at 100 iso at f 5.6?

jc