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Category: New Questions

f stops and shutter speeds

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July 21, 2001

From your question, it sounds like the wedding and/or reception will be outdoors (??).

Exposure Estimating 101:

1. For Bright Sun, or Bright Hazy Sun (front-lighted subjects that cast distinct, sharp shadows):
Aperture of f/16 and shutter speed of 1/(ISO film speed). For ISO 100 film, this would give f/16 @ 1/100th second. Not many cameras can be set to 1/100th, so round to nearest shutter speed. This would be 1/125th on most cameras. You can trade f-stops with shutter speeds; f/16 @ 1/125th is the same exposure as f/11 @ 1/250th, or f/8 @ 1/500th, etc. These examples are exact for ISO 125 film, but work for ISO 100 or ISO 160 also! This setting is often called the "Sunny-16 Rule."

2. Weak Hazy Sun (front-lighted subjects casting shadows in their outline, but with soft edges; sun is visible, but with a diffused outline also):
Add one stop of exposure to the "Sunny 16" setting. Using the example for ISO 100, f/16 @ 1/60th, f/11 @ 1/125th, f/8 @ 1/250th, f/5.6 @ 1/500th, etc.

Note for #1 and #2:
a. for subjects on light sand or snow under lighting from #1 or #2, subtract a stop of exposure.
b. for side-lighted, average subjects, add a stop of exposure.
c. for back-lighted, average subjects close-up, add two stops exposure (at a farther distance filling only about half the frame with bright background add only one stop exposure).

3. Cloudy Bright (no shadows that show an outline or no shadows at all; may be partly cloudy, but sun is obscured by clouds and its location can be determined as a bright spot or area in the clouds):
Add two stops of exposure to the "Sunny 16" setting.

4. Heavy Overcast (no shadows; usually complete, thick cloud cover, and sun location cannot be determined; _no_ large, extremely dark areas like an approaching storm):
Add three stops of exposure to the "Sunny 16" setting.

5. Open Shade (subject shaded by large nearby object such as a building, but with at least 60% unobstructed sky; this is not under thick trees which is Deep Shade):
Add four stops of exposure to the "Sunny 16" setting.

BTW, this is printed without the detailed descriptions on the inside of Kodak film boxes, for the film speed that was in the box. The detailed descriptions should help with the difference between things like bright hazy and weak hazy sun, or what cloudy bright really is. If you have a light meter, check out what it says some time under these conditions. With some experience, the estimating system can get you within about a half stop.

Hope this helps some,
-- John

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July 22, 2001