What Is AF-Lock? (Also FE, AF, AE Lock)

AE Lock, AF, AE buttons on camera

You might have seen FE, AF, AE Lock buttons on your DSLR camera, and you may have wondered what they actually do. These three "lock" buttons are rarely used by many people, especially beginner DSLR photographers, because they simply don't know what they do. However, all three can be incredibly useful!

AE-Lock is a way to lock in the exposure with which you're shooting. AF-Lock works with the focus system of the camera, locking in the focus system. FE-Lock locks in the flash exposure setting.

What Is AE-Lock? 

AE simply stands for automatic exposure. The button allows users to lock their exposure settings (i.e. aperture and shutter speed). AE-lock can be extremely useful in many situations.

AE-lock can allow you to be certain each photo has the same exposure. It can also be very useful in difficult lighting situations. Once you set up the proper exposure in the image, using AE-lock allows you to force the camera to continue using the same exposure, rather than trying to dial in the proper exposure each time you press the shutter button in the tricky lighting situation.

One area where you may want to use AE-lock is in a panoramic photo, where you can force the same exposure throughout every shot in the panoramic photo, which will give you more success when stitching the photos together later.

What Is FE-Lock? 

FE stands for flash exposure. This button allows users to lock their flash exposure settings. With some cameras, the lock only lasts for 15 seconds or for as long as you keep the shutter button half-pressed. Other DSLRs may use a different time frame for the length of time the button remains active, so you'll want to explore this feature a bit more in your camera's user guide before using it, to ensure you understand all of its features and limitations.

On many DSLR cameras, you won't see an FE-lock button. That's because it's tied together with the AE-lock on these types of DSLRs. Often with more expensive DSLRs, the FE-lock will be a separate button. Other cameras allow you to assign FE-lock to a "Custom Function" button. 

It can be useful to use FE-lock with reflective surfaces, which can fool flash metering, or with photos where the subject is not covered by a focus point.

What Is AF-Lock? 

AF stands for autofocus, and AF-lock is the easiest of these lock functions to use. It's also the only one of the three that happens automatically when you take any photo. Hold down the AF-lock button to cause the camera to maintain the same focus point, even if you adjust the composition of the scene after locking in the focus.

AF-lock also can be activated by pressing the shutter button halfway. Photographers often use this technique with all types of cameras, even DSLRs. By keeping your finger on the shutter button as it's pressed halfway, the focus is locked. Because so few cameras have AF-lock buttons, holding the shutter button halfway is a good option.

This can be very useful if you want to focus on a subject that is on one side of an image. You can lock the focus on the subject and then re-compose the image without taking your finger off the shutter button.

As shown in the photo here, sometimes the AE-Lock and AF-Lock are contained on the same button, allowing you to activate both at the same time.