A timer mechanism including a base piece, a top piece, a rod, and a spiral spring.
The base piece includes an inner hub forming a threaded surface and a central passage.
The top piece includes an inner post that a central passage and a threaded surface
for engaging the inner hub. The rod is slidably disposed within the central passages
and is selectively coupled to the top piece. The spiral spring is coaxially wrapped
about the inner hub and terminates in a leading end connected to the top piece.
The top piece is rotatable relative to the bottom piece to a raised position in
which energy is stored by the spiral spring. The spiral spring rotates the top
piece in an opposite direction, causing the top piece to wind relative to the bottom
piece, forcing the rod downwardly for depressing a camera shutter release button.