Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 150)

B: Long (Bulb) Exposures
Bulb Timer
In this mode, the shutter stays open as long as you hold down the shutter button completely,
and closes when you let go of the shutter button. Use bulb exposures for night scenes,
fireworks, astrophotography, and other subjects requiring long exposures.
1.
Set the Mode dial to < >.
2.
Set the desired aperture value.
Turn the < > dial to set it.
3.
Take the picture.
The exposure will continue for as long as you keep the shutter button
pressed completely.
Elapsed exposure time is displayed on the screen.
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