Mike Chan
Mike Chan

Mike is part of the Canon Digital Learning Center team as a Technical Specialist providing Online Educational resources to professional and advanced amateur photographers.

Utilizing the Multi function Lock Switch in the EOS 5D Mark III

November 12, 2013

Most mid-range and high-end Canon EOS cameras with a Quick Control Dial on the back have incorporated a Lock Switch for some time now. The original purpose of the switch (which was built into the on/off switch) was to lock the Quick Control Dial so that there aren’t any unintentional adjustments while the back of the camera was resting on your body. When the EOS 7D came out, the lock switch became its own dedicated switch, located below the Quick Control Dial. With the introduction of the EOS 5D Mark III, the lock switch now has the ability to lock more than just the Quick Control Dial.


Lock switch setup and options

In addition to locking the Quick Control Dial, you now have the ability to lock a combination of the Main Dial, Quick Control Dial and/or Multi-controller.

It’s worth noting that you can override these locked dials by pressing the Q button and modifying the values in the Quick Menu.



To set up the lock switch functionality,

  1. In the Custom Functions menu, locate and highlight "Multi function lock," and press SET.
  2. Choose your desired combination of dials and controllers that you want to lock by checking them off.
  3. Scroll to OK and press the SET button to confirm.

The EOS 60D has a unique "UNLOCK" button, below its multi-function dial on the back of the camera. By default, the large rear Quick Control Dial is always active whenever the camera is awake. In the EOS 60D's 2nd Set-up Menu, there's an entry for "Lock [Quick Control Dial icon]." If you want to prevent accidental movement of the dial from changing your settings, enter this menu item and change it to "ENABLE." Now, to make actual changes with the Quick Control Dial, press the EOS 60D's UNLOCK button first, then promptly turn the dial as needed. When the camera's meter timer goes off, the dial becomes inactive until you press the Unlock button again.

Practical uses

The seemingly obvious and original use of the lock switch is to lock the camera values that you are worried about changing while traveling, transport or when the camera is not in use. Adding the lock switch into your shooting workflow can act as a safeguard while in the heat of the moment.

For example, such situations where the lock switch would be applicable are:

Photo booth/multi-photographer studio setups: If your strobes or Speedlites are setup in a studio setting with multiple stations and multiple photographers, locking your Main Dial and Quick Control Dial ensures that your shutter speed and aperture stays at a constant for the lighting setup, but still allows the photographer to freely move the focus points around to accommodate the subject if the AF point select button is pressed before turning a dial.

Video recording: When shooting video, the ideal shutter speed should be 180° the frame rate (1/50th for 24fps and 1/60th for 30fps). Locking just your Main Dial allows you to ensure that your shutter speed is at a constant while still having the freedom to change your aperture and focus points.

Arena sports: When shooting in an arena where you have access to the house strobes, locking the Main Dial ensures that your shutter speed doesn't change from where you've pre-set it. Depending on the arena and changing lighting situations, it might also be a good idea to lock your Quick Control Dial, thus locking your aperture as well. This will leave the Multi-controller active, to change AF point location if needed.

Shooting portraits with a set shutter speed and aperture: When you have those times when you need to shoot at a specific shutter speed and aperture but still have changing light, lock your Main Dial and Quick Control Dial to ensure your settings will be the same shot after shot. This leaves you with the multi-controller to adjust focus points. To adjust for changing light, set the camera’s ISO to auto and control the exposure with the AE Lock button.

What’s that L?

When the lock switch is active and you accidentally turn a locked dial, the shutter speed and aperture are replaced with an “L” on the top panel, representing an active lock. In live view mode, the shutter speed and aperture are replaced with the word “LOCK.”


While the concept of the lock switch is simple, the options that the camera gives are just one more piece of customization that you can do to personalize your camera to the style of shooting you prefer. When it is crucial that your camera settings do not change, no matter how much you or the camera moves around, the lock switch is the way to go.

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