How to Enable Mirror Lockup on a Canon EOS Rebel T3i - dummies

How to Enable Mirror Lockup on a Canon EOS Rebel T3i

By Julie Adair King

One component involved in the optical system of an SLR camera like the Canon Rebel T3i is a tiny mirror that moves when you press the shutter button. The small vibration caused by the movement of the mirror can result in slight blurring of the image when you use a very slow shutter speed, shoot with a long telephoto lens, or take extreme close-up shots. To eliminate the possibility, your camera offers mirror lockup. When you enable this feature, the mirror movement is completed well before the shot is recorded, thus preventing camera shake.

Mirror lockup shooting requires a slightly different approach to taking a picture. To try out this feature, take these steps:

  1. Set the Mode dial to an advanced exposure mode.

    Mirror lockup isn’t available in the fully automatic exposure modes, so set the dial to P, Tv, Av, M, or A-DEP mode.

  2. Set Custom Function 8, Mirror Lockup, to Enable.


  3. Frame your shot.

  4. If you’re using autofocus, press and hold the shutter button halfway to focus.

    Or if you prefer manual focusing, twist the focusing ring as needed to focus the image.

  5. Press the shutter button all the way down to lock up the mirror. Then release the button.

    At this point, you can no longer see anything through the viewfinder. Don’t panic; that’s normal. The mirror’s function is to enable you to see in the viewfinder the scene that the lens will capture, and mirror lockup prevents it from serving that purpose.

  6. Press the shutter button all the way again.

    The camera then takes the picture.

Using a tripod or another type of support is critical to getting shake-free shots in situations that call for mirror lockup. For even more protection, set your camera to the Self-Timer: 2 second mode and take your hands completely off the camera after you press the shutter button in Step 5. The picture is taken two seconds after the mirror lockup occurs. If you purchased the remote control unit for your camera, you instead can trigger the shutter button using it.