How to Use Auto Exposure Lock on a DSLR Camera

The auto exposure lock (AE-L) function on a DSLR camera lets you physically lock the exposure reading from anywhere in the scene. You can use it on its own or at the point where you focus the image.

Just about all DSLR cameras have an auto exposure lock button. When you press the AE-L button, the current exposure settings are fixed (locked) so that they can’t change as you recompose the shot—even if the level of light alters as you aim the camera elsewhere.

using dslr auto exposure lock

Photo by Priya Saihgal; ISO 250, f/16.0, .5-second exposure.

When the shutter is pressed halfway down, the autofocus mechanism is engaged. As it does so, the camera takes a meter reading and sets the exposure. But what if you want to focus and meter from different parts of the scene?

This is where the auto exposure lock function comes in handy. It lets you take an exposure reading independently of where you want to focus.

The AE-L function is best used with spot or partial metering in order to fix the meter reading from a small area in the scene. This is very useful in lighting conditions that may fool the metering system.

For example, if you shoot a scene that has a bright source in part of the image, an evaluative, matrix, or multizone meter can easily force underexposure. To get the right exposure, you need to take a reading away from the bright region.

This can be easily be done by taking a spot or partial meter reading from a mid-tone area of the scene and then locking that reading by pressing the AE-L button and keeping it pressed until you’ve recomposed and taken the shot. On some cameras you don’t need to keep the AE-L button depressed, on others you do.

The AE-L button can be used if the subject or subjects are positioned off-center in the scene. It is also useful when you’re shooting a sequence of images that you want to be stitched together in order to produce a panoramic photograph. The AE-L function makes sure that every shot taken in the sequence has exactly the same exposure settings.

About the Author:
Chris Smith is a writer for an online photography magazine Photography-Expert.

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8 responses to “How to Use Auto Exposure Lock on a DSLR Camera”

  1. Pega says:

    Interesting post.
    I think so many people just don’t even know this function on their camera.

  2. Des says:

    That was so helpful! I am an old school slr user and used to do this a lot but since having my dslr i have not known how to do this. Thank You!

  3. Melissa says:

    Im guilty of not knowing what that button was or how to use it an my DSLR. Thank you for the simple explination, my manuel was kinda confusing.

  4. Dez says:

    I’m not following this one. I use manual, therefore i set the Aperture and shutter speed myself. Isn’t it just as, if not easier simply setting the exposure as advised above but then simply recomposing the scene without resetting the exposure?

  5. ernaldo says:

    I actually have the AE-L button assigned for back button focus on my D7100. I shoot manual often and its more beneficial in my shooting…

  6. Earl says:

    This is a non-issue in Manual mode.

  7. Neil says:

    Thanks for the tip re: spot metering over matrix for more accuracy.

    I too have a D7100 with the AE-L assigned for back button focusing so I re-assigned the Fn button, under the lens, for AE-L.

  8. Me says:

    Not 100% factual since not all DSLRs, as claimed, have an AEL button or back button focus: Sony A330 has neither.

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