Mirror Lockup To Reduce Camera Vibration Blur - Canon EOS REBEL T7i Instruction Manual

Mirror Lockup to Reduce Camera Vibration BlurN
You can use the mirror lockup function to prevent the disturbing
mechanical vibrations (mirror shock) when shooting with super
telephoto lenses or shooting close-ups (macro photography).
Mirror lockup is enabled by setting [10: Mirror lockup] to
[1:Enable] in [54: Custom Functions (C.Fn)] (p.395).
1
Focus on the subject, then press the shutter button
completely.

The mirror will swing up.
2
Press the shutter button completely again.

The picture is taken and the mirror goes back down.
After taking the picture, set [10: Mirror lockup] to [0:Disable].

Shooting Tips
Using the self-timer <Q>, <l> with mirror lockup

When you press the shutter button completely, the mirror locks up.
The picture will be then taken 10 sec. or 2 sec. later.
Remote control shooting

Since you do not touch the camera when the picture is taken, remote
control shooting together with mirror lockup can further reduce the
camera vibration blur (p.409). With Wireless Remote Control BR-E1
(sold separately) or Remote Controller RC-6 (sold separately) set to
a 2-sec. delay, press the release button (transmit button) to lock up
the mirror, and the picture will be taken 2 sec. after the mirror lockup.
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