-2/3 exposure a la Bryan Peterson

Discussion in 'Beyond the Basics' started by rubbertree, Mar 19, 2008.

  1. rubbertree

    rubbertree TPF Noob!

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    Good afternoon everyone. This is my first post, even though I've been a member and reading here for several months now. I love this forum!
    I am reading "Understanding Exposure" by Bryan Peterson. On page 117 he talks about how he recommends taking an additional exposure at -2/3 (digital) to allow for a comparison.
    If I had taken the first shot at f/8, does he mean the second shot should be at f/10 or f/6.3? I can figure out if -2/3 means up the scale in number (and thus a smaller aperture opening) or down the scale (and thus a larger aperture opening).
    Thanks in advance,
    Rubbertree
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Welcome to the forum (to posting anyway).

    (-) negative exposure compensation means less light.

    On the F-Stop scale, low numbers are bigger apertures and higher numbers are smaller apertures.

    So to let in less light (negative exposure) you would need to make the aperture smaller...which is a higher F number.

    So F10 is 2/3 of a stop less (negative) exposure than F8.
     
  3. Sideburns

    Sideburns TPF Noob!

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    move your dial two clicks towards the bigger numbers basically...

    If you want to try this technique to see how your camera behaves...try AEB (auto exposure bracketing)..it's in your menu and can take 3 shots at 3 different exposures without you changing anything.
     
  4. rubbertree

    rubbertree TPF Noob!

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    Thank you both for your replies and the info.
    So -2/3 = smaller aperture... check!
    I will also try the auto bracketing, i've honestly never tried it before!
    Thanks again,
    Rubbertree
     
  5. ksm

    ksm TPF Noob!

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    You can always change the apertures to change exposures of course but if you are reading Peterson's book you have to understand what he is trying to tell you. Peterson wants you to select the aperture first independant of what the exposure is going to be. He wants you to decide what kind of picture you are trying to take. He calls them "storytelling" (small aperture),"portrait"(bigger aperture) , "singular - theme" (biggest aperture). Then you find the correct exposure using the shutterspeed according to your light meter. Then decrease the shutter speed to get a -2/3 exposure comensation.

    That is what Peterson is trying to say in his book. If you change the aperture you can definately change the exposure also but then you are also changing the effect of the picture (depth of field) that you originally had decided on.

    At least that is my interpretation

    P.S Of course if you were trying to get "movement" in your picture and depth of field wasn't the concern the Shutter speed would be constant and Aperture would change. Had to add this cause I know someone would say something but Peterson mostly choses what kind of "theme" he wants first.
     
  6. tjphotography

    tjphotography TPF Noob!

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    Great books by Peterson. I own both Understanding Exposure and Learning to See Creatively.

    Even as professional, I go back to these books for ideas and questions of my own at times.

    Learning to understand Fstop and aperature numbers is kind of tricky, but Peterson does a good job explaining Aperture in one of his chapters.

    Travis
    www.tjphotography.com
     
  7. petey

    petey TPF Noob!

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    Where does the "2/3" come from though?

    I thought Peterson was saying 2/3 of the +/-. It makes sense that this is wrong however now that I think about it.
     

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