perfect exposure without a meter!

Discussion in 'Beyond the Basics' started by plowed, Apr 6, 2006.

  1. plowed

    plowed TPF Noob!

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    This article was in the outdoorphotographer magazines Dec 2003 issue. the article was written by David Stoecklein. I'm having trouble understanding exposures without a meter. He says on a bright sunny day he shoots 100 film at 1/500 f7.1, now he says he subtacts 1/3 of a stop but he still ends up with 7.1. you really have to see the article to understand what i'm trying to say here.If anybody can explain this to me it would help me understand the article. I beleive what he means is that his base f stop is 7.1 /500 and he opens it up 1/3 of a stop to give more exposure. there are more pictures he took in the article and they make sence to me but not the snow pictures. Any help would be appreciated. I also took this article down to the local Henry's camera store and the two girls there couldn't make any sence of it at all. They beleived the magazine made a mistake.
     
  2. 2framesbelowzero

    2framesbelowzero TPF Noob!

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  3. 'Daniel'

    'Daniel' TPF Noob!

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    If you actually type out what it says we might be able to help.
     
  4. ThomThomsk

    ThomThomsk TPF Noob!

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    It's the sunny 16 rule. This is based on the idea that an average subject (an 18% grey card for example) in bright sun will have an EV (exposure value) of 15. For 100 EI film you would set your camera to f8 at 1/500th to expose this correctly.

    I'd guess that f7.1 is a third of a stop wider than f8 (I could look this up, but you can use Google as well as I can), which is where the subtraction thing comes from. Anyway, the rule is only supposed to give you a rough guide, something to get you close enough that negative film's very wide exposure latitude will deal with any errors and you'll still get something you can print, so a third of a stop either way is unlikely to be a big deal.

    Thomsk
     
  5. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    I agree with Thom

    If he's using sunny 16, then:
    f/16 at 125...
    f/11 at 250
    f/8 at 500 and open 1/3 of a stop you get f/7.1

    The girls at henrys don't know their stuff.
     
  6. plowed

    plowed TPF Noob!

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    Yes it is the sunny f16 rule with a twist. I'm going to copy what he wrote, maybe this will make it easier to understand what I don't understand. Sun and snowboards: With the basic daylight exposure for bright snow as the benchmark (1/500sec. at f/7.1) my decision is based on stopping the action. subjects coming right at you can be stopped with 1/125 or 1/250 sec. If you're panning with a moving subject, almost anything can be stopped with 1/500 sec. Here, I didn't want to pan, so I needed 1/1000sec. therefore, my exposure was 1/1000sec. at f/5.0 ....Basic-1/3[1/1000 f/5.0] So the way I understand it is he shoots at 500 f7.1 he wants to shoot the action so he opens up to f5 at 1000 why is he saying he's using 1/3 less exposure, he has not changed anything. He is shooting at 1000 and f/5 but he has'nt open up or closed by 1/3 anywhere that I find. I which you could see the article as this really bothers me. Well guys and gals thanks for trying.
     
  7. selmerdave

    selmerdave TPF Noob!

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    Plowed, as the others said he is using the sunny 16 rule and but opening up by 1/3 of a stop, that's how you get 1/500 at f/7.1. He's opening up a third of a stop from f8. 1/1000th at f5 is the same exposure, basic sunny 16 rule opened up by a third of a stop.

    Dave
     
  8. plowed

    plowed TPF Noob!

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    Selmerdave you are right but the way he has it written is that he opened up 1/3 of a stopped from his benchmark 7.1 setting he has it written as -1/3 not +1/3 if you can find that article from Dec 2003 in outdoor photographer magazine it would help to explain. Thanks for replying.
     
  9. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    he's supposed to be shooting at 1/500 at f/8

    To get f/7.1 he had to decrease by 1/3 of a stop... or change the aperture by -1/3

    Low aperture = lower number
    Negative change in aperture is opening the lens up
     
  10. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    f/8 +1 stop = f/5.6
    f/8 -1 stop = f/11
    1/125th +1 stop = 1/60th
    1/125th -1 stop = 1/250th

    +stops always refers to an increase in exposure
    -stops always refers to a decrease in exposure

    If people are going to refer to changes in aperture and shutter in +/- stops, they should ignore the numbers on the dials, and worry about actual exposure. Otherwise we all get confused.

    I don't know what a low aperture is. One that's only 3 inches from the ground? Aperture is a hole, so better descriptive terms would be small, large, wide, narrow, etc... The f/# can be low or high, but a low f/# = wide/large aperture.
     
  11. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    Aperture isn't a hole. The iris opening is a hole.

    Aperture is a numerical value. So low aperture is a low numerical value...

    But I agree... few people think of it like that.
     
  12. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Aperture, according to the dictionary: 1) An opening, such as a hole, gap, or slit. 2) A usually adjustable opening in an optical instrument, such as a camera or telescope, that limits the amount of light passing through a lens or onto a mirror. An aperture is a hole.

    An "iris diaphragm" is "a circular device with a variable diameter, commonly used on cameras to regulate the amount of light admitted to a lens" (also from the dictionary). The iris diaphragm is used to vary the size of the opening, but is not the opening itself. I have numerous cameras and lenses that have an apeture(s), but no iris diaphragm.

    The f/# is not the opening itself, but a numerical value describing the opening, as in lens focal length divided by the diameter of the apeture = f/#. The aperture is, plain and simple, the opening. People do use the term interchangably with f/stop.

    Anyone can refer to anything with whatever terms they want. In most circumstances it's not hard to figure out what they mean. But I have noticed an excessive amount of confusion reguarding the opening in the lens, coinsidering it's really a pretty simple concept. I think it's because people use many different ways to describe the same thing, and if we were a little more precise, then the level of confusion might lessen.
     

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