Zoom

Pulls the camera in and pushes it out.

Device	Control
Keyboard + mouse	Scroll wheel
Gamepad	Shoulder buttons — right pulls in, left pushes out
Touch	Pinch

The control is counted in wheel notches, because that is the unit a player's scroll arrives in. A held shoulder is worth six notches a second and a pinch is worth one notch per fifty pixels, so a camera applying one zoomSpeed moves the same amount per gesture on every device.