Auto exposure lock is a function that is not talked about much. I think this is because most photography educators, myself included, recommend learning how to use manual mode. BUT that doesn’t mean that the other modes aren’t good, useful and have their place.
If you photograph in aperture priority, shutter priority or program mode, you will find these auto exposure lock tips helpful.
It’s not so great if you prefer to use back button focusing though. The reason being is that you don’t have enough thumbs.
With that said, let’s explore auto exposure lock, its benefits, as well as why, how and when to use it.
What is auto exposure lock?
On the back of your camera you’ll see a button labelled AE-L. That is your auto exposure lock button and it does what it says on the tin…button. When you depress and hold the auto exposure lock button it locks the exposure.
If you then move the camera to recompose, while still holding down the auto exposure lock button, the exposure settings won’t change, regardless of where you’re pointing your camera.
Why use auto exposure lock?
Let’s say you’re photographing a couple, but you want them off to the side of the scene, not smack bang in the middle of the photo.
You’ll want to ensure that the photograph is correctly exposed for the couple. So you need to be able to expose for them, but then recompose the shot without the exposure changing when you recompose.
How to use auto exposure lock
Using the example above:
- Meter off the couple to get your exposure reading.
- Push and hold down the exposure lock button,
- Recompose and push the shutter button to take the shot.
If you continue to hold down the auto exposure lock button you can continue taking photos at that exposure for as long as you hold down the button. So the couple could move, you could move, you could reframe the image, but the exposure settings would remain the same.
If you find spot metering and single point autofocus confusing, here’s a handy cheat sheet you can download.
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Also, here’s more information: Clearing up the confusion between spot metering and single point autofocus
Why not just reposition the focal point to meter?
Let’s use a headshot as an example.
When photographing people, we focus on the eye. However, exposure should be set for the skin. If you simply move the focal point over the eye and take an exposure reading based off that (using spot metering) it will be wrong.
For a well exposed, sharp headshot photo, follow these steps:
- Meter for correctly exposed skin by positioning the point on their cheek.
- Depress and hold the auto exposure lock button to lock in exposure.
- Recompose and position the focus point over their eye.
- Press the shutter button half way to focus and depress full to take the shot.
You see why this wouldn’t work if you use back button focus with the shutter button for shutter release only? You need to be able to use the shutter button to focus with this technique, because your thumb will be busy holding down the auto exposure lock button.
Is auto exposure lock only for spot metering?
No. You can also use it in the same way with partial or center weighted exposure metering. In this instance you would be exposing for a larger area than with spot metering. For example photographing a dog running on the beach.
There is no point with matrix metering / evaluative metering, because in this situation your camera is exposing for the whole scene anyway.
You’ll find more information on autofocus area modes here: How to focus on fast moving subjects
Why not just use manual mode?
Not every photographer wants to use manual mode. Also, some situations are too fast moving to use manual mode.
I don’t advise using program mode as you leave too much up to the camera to decide and it doesn’t know enough about what you’re photographing. Too much responsibility for your camera and it can make the wrong choices.
However, sometimes it is better to use aperture priority or shutter priority over manual mode. They are much faster than manual mode when there’s a lot going on and you don’t have time to change your settings.
- Confetti toss at a wedding
- Kids playing
- Concert with flashing or moving lights
Final words on auto exposure lock
There are so many ways to arrive at the end result of a sharp, well exposed photograph. Different situations call for different techniques. Knowing all the methods prepares you for all situations.
Auto exposure lock is just one method of achieving a well exposed photo and is well worth practicing for when you might need it.
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