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Thread: AE lock

  1. #1

    Talking AE lock

    I Would like to ask you all a question and would appreciate if you can help me out here.

    Using Canon 10D:

    When and Where should AE (auto exposure ) lock be used:
    Person -- > Face ?
    Group Shots--> Skin ?
    Landscape --> Shaded Parts ?
    Animals --> Fur/Feather ?
    Insects --> Body ?
    Flower --> Petals or Pollen area ?

  2. #2

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    Quote Originally Posted by myloplex
    I Would like to ask you all a question and would appreciate if you can help me out here.

    Using Canon 10D:

    When and Where should AE (auto exposure ) lock be used:
    Person -- > Face ?
    Group Shots--> Skin ?
    Landscape --> Shaded Parts ?
    Animals --> Fur/Feather ?
    Insects --> Body ?
    Flower --> Petals or Pollen area ?
    The basic use of AE Lock is if you want to lock the meter reading on a certain part of the subj (normally a mid-tone) and then recomposing your shot. You should not work based on "what is the subject" alone, but rather "what is the tone of the subject".
    One basic example is if you want to get the proper exposure of person wearing a mid-tone dress (e.g. gray), you should not lock the exposure on the person's face (in general, it's 1 stop lighter), but rather you should lock the exposure on the gray dress then recompose your shot.

  3. #3

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    Where should I AE lock for these pictures I took ?

    Hair ? Dark Blue Shirt ?


    women's hair ?


    Tortise ?


    Duck face ?
    Last edited by myloplex; 1st September 2003 at 04:21 PM.

  4. #4

    Default

    Quote Originally Posted by Sgt. Pepper
    The basic use of AE Lock is if you want to lock the meter reading on a certain part of the subj (normally a mid-tone) and then recomposing your shot. You should not work based on "what is the subject" alone, but rather "what is the tone of the subject".
    One basic example is if you want to get the proper exposure of person wearing a mid-tone dress (e.g. gray), you should not lock the exposure on the person's face (in general, it's 1 stop lighter), but rather you should lock the exposure on the gray dress then recompose your shot.

    Sgt pepper, how to know which area is midtone?

  5. #5
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    Default The COncept of SBR - Subject Brightness Range

    Hieee....

    As we all know - A photo is captured as a FRAME, you may sometimes run into a situation like for example the DUCK photo .

    Fortunately this photo is okay as the sun shine on the water is not that glaring. So if you do a spot meter AE lock on the Duck's face, the behind-ground may become brighter BUT in this case the water ripple still keeps its detail.

    But in cases where the the sun is shining brighter, there is a risk of the details on the ripples to be loss - due to higher/brighter lighting.
    Hence the need to AE lock on the water ripple.
    However....this will make the face of the duck DARK/Black .

    Therefore you need to use a fill flash (diffused preffered) to light up the face of the duck.

    The above in the general...approach for back lit subjects like person infront of an open window with bright sunlight...etc.

    Have anyone tried B&W preview in digital to determine the mid-gray ??...

    Regards,
    me
    Last edited by sulhan; 2nd September 2003 at 10:13 AM.

  6. #6

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    Quote Originally Posted by Falcon
    Sgt pepper, how to know which area is midtone?
    Well, tonality refers to the warmth or coolness of a color. I don’t know how to explain it in my own words, but middle tone color should be neutral side of every color. E.g. medium gray, green leaf, etc.. (not-so-light and not-so-dark colors)

    It's all up to you, how you want your image to appear. Work on 'stops' and know how to identify the tonality.

    If you want the mid-tone to appear as is, then meter on the midtone, locked, recompose, and shoot (this is, of course, provided that the same amount of light is falling on the area you metered and your subj).

    If you want the mid-tone to appear darker, then compenste the exposure by stepping down by 1 stop (depends on how dark you want).. If you want it to appear as lighter than the midtone, then open up by a certain stops.

    Sulhan is right about using a flash to expose the backlighted subject against a bright background. If you will meter the dark portion of the duck’s face, you may end up blowing out the highlights. In this instance, you may meter the green leaf from the background to properly expose it, then let the flash expose the duck itself.

    Personally, I always try to find a midtone with in the frame and get the meter reading from there. What if there’s NO midtone? Then, select any color tone, say, dark green (which is 1 stop darker from the medium green) and get the meter reading from there. Assuming you want this dark green to appear as dark green, then you have to compensate the exposure by –1 stop, otherwise, this will appear as medium green. Remember the your camera will always make the area that you have metered a midtone.

    Hope it helps.

  7. #7

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    The short answer is that you should AE Lock on the part of the picture which you wish to be correctly exposed.

    The long answer is to ask yourself whether you need to use AE Lock at all, 95% of the time. With evaluative metering, you can arrive at a properly exposed scene regardless of whether you AE Lock or not. After that, it's a simple matter of adjusting curves to fine tune the exposure. Yes, you DO lose some dynamic range, but in my opinion it's not noticeable.

    The only time I would use AE Lock (using partial metering) is when there is a high contrast scene (eg bright sunlight, subject in shadow), because adjusting curves after that results in unacceptable loss of details.

    I would rather concentrate on focus and composition.

  8. #8

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    Tks Sgt Pepper for detailed explanation regarding midtone.

  9. #9

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    Quote Originally Posted by StreetShooter
    The short answer is that you should AE Lock on the part of the picture which you wish to be correctly exposed.
    I'm afraid that AE lock (by pressing the shutter halfway or pressing '*' for 10D) does not give an assurance that the part of a subj will be correctly exposed. It will only lock the exposure based on the type of metering you use. If you will use Av or Tv (using partial/spot metering) and meter on a black shirt wore by a typical mid-brown skinned person, then may end up getting a pale skinned person wearing a dark gray shirt.

    Correct me if im wrong.

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