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Thread: Let me get this right about exposure lock and focus locking

  1. #1

    Default Let me get this right about exposure lock and focus locking

    Am I right to say that

    1. if u press the shutter halfway it not only locks the focus but also the exposure?

    2. if my foreground is dark and my background is bright but I want my focus to be on the foreground and exposure set to that of the background as I want the shot to be slightly underexposed so I can use shadow/highlights to bring out the darker details in the foreground in PS. If I were to set my exposure on the dark foreground that the lights in the backgrond would be blown and details are lost and no way to recover them.

    So is the proper way to achieve this by first focusing on the background (depress shutter halfway), then use the exposure lock on my D50 to lock the exposure, then release finger from the shutter, recompose and focus on the foreground pressing the shutter halfway, and press the shutter with the exposure lock on?

  2. #2
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    Default Re: Let me get this right about exposure lock and focus locking

    Quote Originally Posted by boroangel View Post
    Am I right to say that

    1. if u press the shutter halfway it not only locks the focus but also the exposure?

    2. if my foreground is dark and my background is bright but I want my focus to be on the foreground and exposure set to that of the background as I want the shot to be slightly underexposed so I can use shadow/highlights to bring out the darker details in the foreground in PS. If I were to set my exposure on the dark foreground that the lights in the backgrond would be blown and details are lost and no way to recover them.

    So is the proper way to achieve this by first focusing on the background (depress shutter halfway), then use the exposure lock on my D50 to lock the exposure, then release finger from the shutter, recompose and focus on the foreground pressing the shutter halfway, and press the shutter with the exposure lock on?
    depends on your setting for 14. AE-L/AF-L. different setting must use different method to achieve the same result.

  3. #3
    Senior Member zac08's Avatar
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    Default Re: Let me get this right about exposure lock and focus locking

    Quote Originally Posted by boroangel View Post
    Am I right to say that

    1. if u press the shutter halfway it not only locks the focus but also the exposure?

    2. if my foreground is dark and my background is bright but I want my focus to be on the foreground and exposure set to that of the background as I want the shot to be slightly underexposed so I can use shadow/highlights to bring out the darker details in the foreground in PS. If I were to set my exposure on the dark foreground that the lights in the backgrond would be blown and details are lost and no way to recover them.

    So is the proper way to achieve this by first focusing on the background (depress shutter halfway), then use the exposure lock on my D50 to lock the exposure, then release finger from the shutter, recompose and focus on the foreground pressing the shutter halfway, and press the shutter with the exposure lock on?
    First things first...

    check your metering method. If you're on Matrix metering, where you point may not affect the metering much. Change to centre weight or spot.

    1. Not true... In S or A mode, the variables still can change when you meter at different zones.

    2. You will not be able to change focal point after you lock the AE-L/AF-L when you are in autofocus mode. (You can only change focus in manual focus mode)

    Try it out at home on differently coloured locations for a test and you'll get more ideas on the subject.
    Michael Lim
    My Flickr Site

  4. #4

    Default Re: Let me get this right about exposure lock and focus locking

    Quote Originally Posted by boroangel View Post
    Am I right to say that

    1. if u press the shutter halfway it not only locks the focus but also the exposure?

    2. if my foreground is dark and my background is bright but I want my focus to be on the foreground and exposure set to that of the background as I want the shot to be slightly underexposed so I can use shadow/highlights to bring out the darker details in the foreground in PS. If I were to set my exposure on the dark foreground that the lights in the backgrond would be blown and details are lost and no way to recover them.

    So is the proper way to achieve this by first focusing on the background (depress shutter halfway), then use the exposure lock on my D50 to lock the exposure, then release finger from the shutter, recompose and focus on the foreground pressing the shutter halfway, and press the shutter with the exposure lock on?
    1. Generally true but not always true. What is locked (focus or exposure) may depend on your setting of your AE/AF Lock button in your camera setup menu. So you better check your user manual. For e.g., for my Nikon 5700, at default, my AE-L/AF Lock button would lock both focus and exposure and half pressing my shutter release button locks both focus and exposure. When my AE-L/AF lock button is set to lock only exposure, then half-pressing my shutter release button will lock only focus. When my AE-L/AF-L lock button is set to lock only focus, then half-pressing my shutter release button will lock only exposure.

    2. How to get the exposure you want depends on what your AF/AE lock button is set to (lock focus or lock exposure).

    Your method of focusing on the background first and lock the exposure by holding the AF/AE lock button would work only if your AF/AE lock button is set to lock only exposure (so that focus is not locked as well by the AF/AE lock button).
    Last edited by Clockunder; 29th October 2006 at 11:52 PM.

  5. #5

    Default Re: Let me get this right about exposure lock and focus locking

    Quote Originally Posted by zac08 View Post
    First things first...

    check your metering method. If you're on Matrix metering, where you point may not affect the metering much. Change to centre weight or spot.

    1. Not true... In S or A mode, the variables still can change when you meter at different zones.

    2. You will not be able to change focal point after you lock the AE-L/AF-L when you are in autofocus mode. (You can only change focus in manual focus mode)

    Try it out at home on differently coloured locations for a test and you'll get more ideas on the subject.
    Ok I always matrix metering as center or spot is a bit tricky for a newbie like me...

    ZAc08...I know what u mean by "If you're on Matrix metering, where you point may not affect the metering much." but I am assuming a case where the dynamic range is big say between a foreground object and a setting sun...or afternoon sun...can use bracketing but thats another matter altogether...

    So basically what I m doing for 2 works as long as I change the AE-L/AF-L to lock exposure only right?

    Zac,

    2. You will not be able to change focal point after you lock the AE-L/AF-L when you are in autofocus mode. (You can only change focus in manual focus mode)
    If I change the AE-L/AF-L to lock exposure only then autofocus can work right?

  6. #6
    Senior Member zac08's Avatar
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    Default Re: Let me get this right about exposure lock and focus locking

    Quote Originally Posted by boroangel View Post
    Ok I always matrix metering as center or spot is a bit tricky for a newbie like me...

    ZAc08...I know what u mean by "If you're on Matrix metering, where you point may not affect the metering much." but I am assuming a case where the dynamic range is big say between a foreground object and a setting sun...or afternoon sun...can use bracketing but thats another matter altogether...

    So basically what I m doing for 2 works as long as I change the AE-L/AF-L to lock exposure only right?
    Let me try to answer correctly.. Matrix metering measures all the zones within the picture and tries to get the average setting where all the zones will be exposed correctly. When you change the focal point/metering point in the screen, there's no change in the metered values as the composition and picture lighting is still the same.

    But when you change to centre weight or spot metering, the different zones metered WILL definitely give you a change in the values. You can do a simple experiment by metering a lighted area of your room and use the different metering modes at the different zones. Check the values it give you.


    Quote Originally Posted by boroangel View Post
    If I change the AE-L/AF-L to lock exposure only then autofocus can work right?
    Yes, when you lock ONLY the AE-L, the autofocus can still work.
    Michael Lim
    My Flickr Site

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