Canon F1-N Brochure & Specs page 60

25 SELF-TIMER
If you have started the self-timer and wish to cancel its operation, press the
battery check button.
Eyepiece Shutter
If your eye will not be to the eyepiece during shutter release, close the eyepiece
shutter to prevent stray light from entering and causing underexposure. This is
particularly important in self-timer AE photography, and also applies to remote
control and night photography.
To close the eyepiece shutter, push the lever clockwise. The red dot is a reminder
that the eyepiece shutter is in place.
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