Exposure Compensation

Discussion in 'Photography Beginners' Forum' started by hawee99, Sep 12, 2007.

  1. hawee99

    hawee99 TPF Noob!

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    I'm hoping someone can explain this better than my book. I can't seem to fully understand it. Exposure Comp is that little +- button correct?
    What does it actually do? I understand this is supposed to make the picures brighter or darker, but on what level. When you go +1 or -1, does this actually effect the shutter or aperature. I don't think so, but I don't understand. When I have used this button in the past I have noticed it affect my light meter a lot, but I haven't noticed much different in the picture.
    Also, when shooting in "bracketing" , I understand it's supposed to take shots and different EV, example -2, 0, +2. When I shoot in bracket mode, I notice the shutter speed changing.
    Let me now if a can give anymore details to help understand my questions.
    Thanks.
    Nikon D80
     
  2. MarkCSmith

    MarkCSmith TPF Noob!

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    It changes the aperature and shutter settings I believe.
     
  3. Sideburns

    Sideburns TPF Noob!

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    when bracketing is changing the shutter speed that over and underexposes the shot by 2 stops either way...it doesn't change aperture because then DOF would change.
     
  4. TCimages

    TCimages TPF Noob!

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    It changes both depending what mode you are in.
     
  5. hawee99

    hawee99 TPF Noob!

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    so if that's the case, why even have the button, i can change the shutter speed the normal way in manual mode
     
  6. TCimages

    TCimages TPF Noob!

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    you can change the shutter speeds or aperture to change exposure, but EC allows you to easily change the exposure in incremental stops. I guess if you know what the shutter speed and/or aperture equivalent for each stop would be (for every scene) then you may be able to do it.

    Imagine shooting some flowers next to your house which is a bright white wall. The white wall will fool the cameras metering system into under exposing the flowers. So you will need to use the EC to stop the exposure up +1 or +1 1/2 . Hope that makes sense.

    With Practice, you will learn how many stop to add or subtract from a scene to get the correct exposure. The Camera will get it right probably 9 times out of 10.

    One thing I want to add, I think the EC actually alters the metering of the camera which impacts the shutter and/or aperture.
     
  7. Alex_B

    Alex_B No longer a newbie, moving up!

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    Simple answer: you do not need Exposure Compensation when shooting manual! It only makes sense when you shoot in those semi-automatic modes like aperture priority or shutter priority or fully automatic. in these modes the amount of light hitting your sensor is defined by your meter reading only, and without Exposure Compensation you would have not chance to influence this amount of light.
    The light meter however, does not read your mind and hence does not know if you consider a scene exposed too bright or too dark and how you would like to get it exposed.
     
  8. Alex_B

    Alex_B No longer a newbie, moving up!

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    I have used several cameras, and seen images from even more cameras. So I would say this is simply wrong ;)

    It is true for standard blue sky outdoor photography with the sun somewhere behind your back. It is also true for for well controlled studio light. But in all other cases cameras and their meters tend to fail totally.
     
  9. EOS_JD

    EOS_JD TPF Noob!

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    Reading "Understanding Exposure" by Bryan Petersen helped me grasp what this was and how to use it.

    Now I regularly use EC. Keep an eye on the histogram and if you have under/over exposed an image try to understand why the camera's meter was fooled and then add/subtract an appropriate amount of EC until you get the correct exposure.
     
  10. The_Traveler

    The_Traveler Completely Counter-dependent Supporting Member

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    these sentences are the key answer.

    If the sun is behind the subject and the sun's glare is affecting the meter too much so that, without EC the subject would be underexposed, you would use EC to increase the exposure so that the subject is correctly exposed.
     
  11. hawee99

    hawee99 TPF Noob!

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    yup that makes sense. thanks everybody for your replies. all very helpful, gotta go mess around with it now
     
  12. sabbath999

    sabbath999 No longer a newbie, moving up!

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    There is also another issue... remember, the "correct" exposure levels are determined by the engineers at the company that made your camera... and their views may or may not agree with your own.

    Also, like all things mechanical, there are trade offs... some cameras meter dark central subjects with brighter backgrounds completely differently... some cameras within the same line are even different.

    I find that there are differences between metering the exact same scene between a D200, a D80 and a D40.

    I often use a -0.7 on my D80 because I find that it overexposes a lot (IMHO) and work from there.

    Histograms and Chimping are your friends.
     

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