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Do you ever notice that sometimes, when you capture a series of photos, they all appear to have different exposures? One might be darker than the previous, and the next is brighter?
But they were all captured in the same light, so why would they be different? Don’t you want them to have the same exposure so they have a consistent look?
This is why cameras have an Auto Exposure Lock.
Refresher on exposure modes
It’s important to have a solid understanding of your camera’s exposure modes before knowing how to use Auto Exposure Lock.
Nearly all cameras have four basic exposure modes – Program Auto (P), Aperture Priority (A/Av), Shutter Priority (S/Tv), and Manual (M). Even though only one of those has “Auto” in the name, all but one have an automatic element chosen by the camera.
This means that the camera is choosing your exposure – how bright or dark the final picture will be. You can have a say in this using the Exposure Compensation dial, but that’s still just a reference based on what the camera is seeing through the lens.
If you need a refresher on exposure and how these exposure modes work, you can go through my free Exposure Triangle for Beginners course.
What is Auto Exposure Lock?
Auto Exposure Lock lets you use these auto exposure modes as a pseudo-manual mode.
One of the biggest benefits of this is consistency from photo to photo.
Without Auto Exposure Lock (AEL), your exposure may be slightly different in each photo of a series depending on the composition. The camera calculates a new exposure each time you move the camera or zoom your lens. If most of your frame consists of something dark in the first photo, then the next photo a second later mostly consists of something bright, those two photos will be exposed differently.
Why would you want the exposure to change each time you press the shutter button if your lighting and subject aren’t changing?
Auto Exposure Lock will lock in that exposure so that it’s consistent as you recompose your photos. No matter how you change your composition, you’ll have the same exposure from one photo to the next while it’s locked.
Before mirrorless cameras, AEL was also important for metering. Photographers would meter off of a known reflective surface, lock the exposure, and then recompose the photo. This is a bit of a lost art form in today’s digital cameras, but AEL still has value for getting those consistent exposures.
How to use the AEL button
Each camera manufacturer has different user-interface designs for AEL. I’d recommend going to your camera manual’s index and reading about Auto Exposure Lock.
AEL button “preflight”
Aside from knowing where your AEL button is, it’s also important to understand how the button behaves.
Do you need to keep smashing it down with your thumb to keep the exposure locked? Or does the button behave more like a switch, where you push and release it to lock the exposure, then push and release it again to unlock it? Can you program it in any way?
Again, this is something that your camera manual will be able to answer better than I can cover countless different cameras here.
But let’s take Fujifilm cameras, for example. Most Fujifilm cameras allow you to program this button. You can decide if the exposure is locked only while you’re pushing the button or if that button behaves like a lock on/off switch.
I prefer to use the “when pressing” option so that my forgetful mind doesn’t accidentally leave it locked when I don’t need it 🙂
When to push the AEL button
You’ll push the AEL button when your frame is exposed as you want it.
How do you know when that is? Well, that’s an entirely different and broad topic! You’ll use your Exposure Compensation dial to make the photo brighter or darker. You can use your histogram to determine the proper Exposure Compensation value if you know how to use the histogram.
Once that is set, push your AEL button.
What you see
There are different symbols in different cameras that indicate an exposure lock. Consult with your manual.
In many cameras, it’s an asterisk somewhere in the display, usually next to the exposure variables. Some cameras will display “EL”, for Exposure Lock. As long as your camera shows this symbol, the exposure variables are locked. You can recompose all you want now, and the exposure variables won’t change!
Then you just release the button or unlock it when you’re done with that sequence or if the lighting changes.
Auto Exposure Lock is one of the oldest exposure tools found in digital cameras. A tool to help you get consistent exposures from one photo to the next.
However, with all of the new tools in more modern cameras, many photographers don’t even know this feature exists. Or what it does.
The key, like everything else, is knowing what it does and when to use it.
You don’t need to use it all the time, but you should know the situations in which it will help your photography, and how to use it.
It just might save your bacon one day!