Exposure Rules of Thumb

Discussion in '35mm Cameras' started by Elie A Shammas, Jan 18, 2004.

  1. If you were given a meter-less camera loaded with an iso100 film, how
    accurately can you predict the right exposure of a random scene? I mean
    guessing shutter speed and aperture.

    Do you know of any rules of thumb that help in determining the right
    exposure? or at least narrowing down your gues. Any magic numbers for
    sunny midday or gloomy afternoon ...?

    Elie A Shammas, Jan 18, 2004
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  2. Elie A Shammas

    Nick Zentena Guest

    Outdoors? Look up sunny 16. Or just check that little sheet of paper that
    comes with film. Still does doesn't it? There are other rules.

    Nick Zentena, Jan 18, 2004
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  3. The classic is the Sunny 16 rule. On a bright sunny day in direct
    sunlight, set the aperture to f-16. Your correct shutter speed should be
    the reciprocal of the film speed - in other words, 1/100 for 100 speed
    film, 1/400 for 400 speed, and so on.

    Increase exposure one stop for hazy days, two for mostly cloudy or
    bright sunset conditions, three for overcast or late sunset. Shadow sides
    are typically 1.5 to 2 stops darker, but this varies depending on
    surroundings. Snow, bright sand, or nearby water will improve light by
    about a stop, so exposure should be decreased, regardless of side you're
    shooting from.

    Indoors? The light is too widely variable to make a decent rule.

    - Al.
    Al Denelsbeck, Jan 18, 2004
  4. Elie A Shammas

    Peter Irwin Guest

    You can look under "sunny 16" on go ogle. The basic rules are these:

    From 2 hours after sunrise to 2 hours before sunset.
    Speed = 1/EI

    f/22 - Sun on light sand or snow
    f/16 - Bright Sun (with sharp shadows)
    f/11 - Hazy Bright (with soft shadows)
    f/8 - Cloudy Bright (no shadows - bright but with sun behind a cloud)
    f/5.6- Open shade under bright conditions.

    If there are a lot of grey clouds, it could be anywhere
    from f/2.8 to f/5.6, you can guess based on experience.

    Under f/16, bright sun conditions:
    Side lighting -> f/11 (open one stop)
    Back lighting -> f/8 (open two stops)

    If you are using print film, you might do better to select
    an EI of half the rated ISO speed, because negatives have
    more latitude on the overexposure side.

    Lots of people got decent Kodachrome slides from these rules,
    so they can actually get you pretty near spot on fairly often.

    To trade between speed and aperture in your head quickly,
    you can remember that if you use half the aperture, you
    use four times the speed. So if the rule says f/11 at
    1/125 of a second, you can easily convert this to f/5.6
    at 1/500 second or f/22 at 1/30 second.

    Peter Irwin, Jan 18, 2004
  5. Elie A Shammas

    T P Guest

    Sunny f/16 rule: Sunny mid-day, set the shutter to the speed nearest
    the ISO number, and the aperture to f/16 ...

    .... 1/125 at f/16 should do it.
    T P, Jan 18, 2004
  6. Elie A Shammas

    Bob Hickey Guest

    look at your own shadow in the sun. Razor sharp shadow = f16, hardly any
    shadow is f5.6. Guess from there. Set your shutter according to experience;
    most 400 film will work best @ 1/250. The slower the film the closer to the
    rating. ie: You can often set ISO 125 close to 1/125, but then if you go to
    ISO 3200 you may get best results rating it at 800/1,000. It takes
    practice and stick to one film once you get what you want. Bob Hickey
    Bob Hickey, Jan 19, 2004
  7. Elie A Shammas

    Kevin Backs Guest

    I've written a little photo-applet that deals with just that problem.

    It and a couple of other free photo-applets I've written are available


    Please feel free to download and share these applets.
    Let me know if you find any of them to be useful. let me know if you
    have any suggestions to improve them, or if there are any other
    photo-calculators that you would like to see.

    -Kevin Backs

    my email:
    kbacks @[email protected] rogers .dot. com

    spam bait:
    [email protected]
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    Kevin Backs, Jan 19, 2004
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