Dark haired cows mess up exposure

Discussion in 'Digital Photography' started by valdore, Sep 24, 2008.

  1. valdore macrumors 65816

    valdore

    Joined:
    Jan 9, 2007
    Location:
    Kansas City, Missouri. USA
    #1
    This may seem like an incredibly rudimentary question, but as you can see with this photo, the camera metered to get proper exposure of the cows in the foreground, leaving the background all blown out.

    Is the only solution post-production tricks like HDR or is there a way to compensate for this in the field?
     

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  2. thr33face macrumors 6502

    Joined:
    May 28, 2006
    #2
    You could dial in some negative exposure compensation in the field.

    For this particular scene maybe -0.7 or -1.0 will do the trick.
    Of course the blacks will get blacker, but you could brighten the shadows a bit in post without affecting the highlights.
     
  3. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #3
    This is a classic example used in many beginning photography texts of how and automatic meter can fail to give the correct exposure.

    Some ways to correct it are

    • Meter off some mid tone object that is in the same light. Green grass works well for this. Lock the expoure then re-aim the camera at the real subject.
    • Simply remember to under expose dark subjects and dial in -ev compensation
    • read up on the zone system, use the camera's spot meter and "place" the dark fir in the desired zone.
    • Or, If this is a digital camera always expose as much as possible such that there are no blown highlights except for self-luminous objects. Place the highlight just below your camera's clipping threshold. Use the histogram display to get this right. This requires a test exposure or two but after that the exposure remains the same until the light changes

    Either of these will get you about the correct result.
     
  4. Phrasikleia macrumors 601

    Phrasikleia

    Joined:
    Feb 24, 2008
    Location:
    Over there------->
    #4
    How does one determine a camera's clipping threshold?
     
  5. jpsalvesen macrumors newbie

    Joined:
    Apr 16, 2007
    #5
    I'd put my camera into high-light spot-metering and take a metering off either the sky or the white on the head of that brown cow.

    As the other people said, you can also just check your histogram and try different negative exposure compensations until your histogram looks about right.
     
  6. John T macrumors 68020

    John T

    Joined:
    Mar 18, 2006
    Location:
    UK.
    #6
    Learning how to balance exposure was one of the first basic techniques those of us who were brought up on film cameras with separate meters had to learn!

    Even nowadays, particularly in relatively high contrast situations, I find (as ChrisA says) I automatically spot meter a "mid tone", lock the exposure and recompose.

    Modern cameras which give the impression to being able to do everything are not infallible and this is where a good knowledge of basic photographic technique is essential for consistently good results.
     
  7. theblueone macrumors member

    Joined:
    Aug 5, 2007
    #7
    Essentially, what Chris A said. You're camera's automatic-exposure meter is going to treat whatever your camera's exposure meter is pointing at as if it were a middle grey(i.e. 18% grey). As it appears, you metered off the black cows. That's great, but your camera, by default, thinks those black cows (at levels of[probably] 70-80% grey) are 18% grey. It will compensate for what it thinks is a deadly dark shot (the black cows) by overexposing in order to bring out highlights. So, you'll see a lot of highlights in the dark cows, but the rest of the frame, as you notice, is dangerously overexposed.

    You could have fixed this for sure by having that front cow hold a grey card in its mouth, off of which you would have exposed that shot perfectly. If you prefer not getting so close to the cows as to put an 18%-grey card in its mouth, you can expose off of something near 18% grey. I would have probably chosen the grass in front of the cows. Greenish shades are often the nearest to 18% as you can get, and I think that deadish grass might have sufficed.

    I'm sure this is a difficult shot to meter as there's so much light/dark polarity with the light/dark cows, but if you stick to something in the middle, I think you would have come closer to exposing this shot more to your liking. I'm guessing you either spot-metered or used a center-weighted metering. Maybe if you'd used a full-frame averaging metering, it might have exposed correctly, but I'm not sure, judging by the amount of dark black in the frame.

    Edit. As I look at the frame again, I think maybe you would have done really well to meter off
    "How-now-brown-cow's" leg/shoulder/breast region. That would have likely exposed him(her) well and gotten a good amount of detail from the grass, the blackish cows and the background.

    The way I would have thought of it is like this: "If I meter off the blackest of cows, the rest of the frame will be really bright since the camera thinks this is a really dark shot. Or...If I meter off their white faces, the rest of the frame will be underexposed since the camera thinks this is a really bright shot. I might as well stick with metering off of something in the middle."

    Further edit: If your question is a simple technical question about how to meter with your camera, you simply half-click the shutter as you are pointing towards whatever you want to meter, in this case probably brown cow. Then you'll probably click the AE-L button to lock that metering as how you want your camera to expose the frame, then compose your shot and fire the shutter.

    Sorry if this is stuff you already know. I really admire your work, Valdore. I just teach "America's future" so I'm kind of stuck in the mode of giving simplistic advice in the hope that it'll stick with someone.
     

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