Nikon D300 User Manual page 736

the Shutter-release button when the camera is on a tripod and
in MUP mode. Touching the camera seems a bit silly after
going to all that trouble to stabilize the camera and raise the
mirror. A finger press could shake the entire tripod! If you do
not have an electronic cable release, simply wait 30 seconds
after raising the mirror and the camera will fire on its own.
There is a built-in 30-second delay after you've raised the
mirror and then the shutter will fire. This could be used as a
slow but high-quality self-timer.
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