Using The Eyepiece Cover - Canon REBEL T3I EOS 600D User Manual

Remote Control Shooting
F Remote Switch RS-60E3 (Sold separately)
Remote Switch RS-60E3 (sold separately) comes with an approx.
60 cm/2.0 ft cord. When connected to the camera's remote control
terminal, Remote Switch RS-60E3 can be used to press the shutter
button halfway and completely.

Using the Eyepiece Cover

When you use the self-timer, bulb, or Remote Switch and do not look
through the viewfinder, stray light entering the viewfinder can cause the
image to look dark. To prevent this, use the eyepiece cover (p.25)
attached to the camera strap.
During Live View shooting and movie shooting, attaching the
eyepiece cover is unnecessary.
262
Remove the eyecup.
1
Push the bottom of the eyecup to
remove.
Attach the eyepiece cover.
2
Slide the eyepiece cover down into
the eyepiece groove to attach it.
After taking the picture, detach the
eyepiece cover and attach the
eyecup by sliding it down the
eyepiece groove.