AE, FE & AF Lock

Alpha Tutorial :23 - AE, FE & AF Lock

AE Lock (AEL) stands for Auto Exposure Lock. Most advanced compact, DSLR and mirrorless camera models have a dedicated button to activate AE lock.

AE Lock button position on the Sony α99.

AE Lock button position on the Sony α99.

AE Lock button position on the Sony α7/α7R.

AE Lock button position on the Sony α7/α7R.

When to Use AE Lock?

When shooting in Program, Shutter priority or Aperture priority modes, the camera will detect the amount of light in the scene and calculate the appropriate exposure (depending on the metering mode you set it on).

  • In Program mode, the camera will set both the shutter speed and aperture automatically.
  • In Shutter priority mode, the camera will automatically set the aperture based on the shutter speed you have selected.
  • In Aperture priority mode, the camera will automatically set the shutter speed based on the aperture you have selected.

However, the camera’s light meter can sometimes be confused when shooting in scenes with high contrast lighting, or when you intend to achieve certain photographic effects like silhouettes.

In such cases, you can use AE Lock to meter the scene by pressing and holding the AE Lock button after the camera has achieved focus lock on the subject you wish to have properly exposed, before you re-composing the photo and shoot.

How to Use AE Lock?

Using AE Lock is a simple three step process:

1) Point the camera at the desired subject or element within the frame that you wish to have properly exposed. Then half-press the shutter release to achieve an autofocus lock. This step ensures that your camera knows this is definitely your main subject.

2) With the camera pointed at your subject, press and hold the AE Lock button to prevent the current exposure settings from changing.

  • In Program mode, both shutter speed and aperture will be locked and cannot change.
  • In Shutter priority mode, the aperture will be locked.
  • In Aperture priority mode, the shutter speed will be locked.

3) While holding the AE Lock button down, you can now re-compose the photo and shoot. Holding the AE Lock button will prevent the camera from changing the variable setting that you have set to expose the subject or element you want properly exposed.

Here are two scenarios, with examples, where AEL was required to achieve the desired exposure.

Example 1: High Contrast Scenes

AEL is particularly useful for photos of off-center subjects; especially those in high contrast lighting. Here, the orchids were under a shade while the rest of the background was well lit.

Without AEL, the camera would try to even the exposure by increasing the shutter speed or making the aperture smaller so as to expose the bright sky at the expense of darkening the main subjects – the orchids.

Without AEL, the camera would try to even the exposure by increasing the shutter speed or making the aperture smaller so as to expose the bright sky at the expense of darkening the main subjects – the orchids.

If you were to simply point your camera at the opera house and shot, it would have most likely resulted in this photo where the camera tried to expose the opera house properly, but overexposed the rest of the scene.

While holding down the AEL button down, you can then recomposed the photo to your desired original framing and shoot. The final shot should have the orchids properly exposed.

Example 2: Creative Silhouette Effects

In this scene, we wanted to accentuate the distinctive shape of the roof of the Sydney Opera House as a silhouette over the backdrop of the orange sky.

To achieve this effect, you should first frame the sunset sky instead – which is the element you want to expose properly. You should then half-press the shutter to measure the exposure. You might not get an AF lock here, but you should still be able to set the desired exposure – then press the AEL button. This will prevent the camera from changing the settings any further.

If you were to simply point your camera at the opera house and shot, it would have most likely resulted in this photo where the camera tried to expose the opera house properly, but overexposed the rest of the scene.

While holding the AEL button down, recompose the shot back down towards the Opera House and shoot. You should be able to get this silhouette photo.

To achieve this effect, you should first frame the sunset sky instead – which is the element you want to expose properly. You should then half-press the shutter to measure the exposure. You might not get an AF lock here, but you should still be able to set the desired exposure – then press the AEL button. This will prevent the camera from changing the settings any further.

While holding the AEL button down, recompose the shot back down towards the Opera House and shoot. You should be able to get this silhouette photo.

What about FE and AF Lock?

FE Lock (FEL) stands for Flash Exposure Lock and has the same concept and use as AE Lock, except instead of locking ambient exposure settings, it is used to lock down your flash exposure settings, when shooting with flash. Not every camera has an FEL button or option however. The Sony α99 has a custom mappable FEL function that is default to the “C” button in the front.

AF Lock stands for Autofocus Lock and is actually the default locking function that happens every time you shoot a photo so there’s no extra procedure to perform. Basically, every time you half-press the shutter to achieve autofocus, AF Lock kicks in. As long as the shutter remains half-pressed, the lock will be in place.