Zoom Tool
Move camera (your view) in or out.
Tool Operation
Click and hold anywhere in drawing area.
Drag cursor up to zoom in (closer to model) and down to zoom out (farther from model).
Modifier Keys
Shift = Change field of view degrees
Esc = Enable previously selected tool
Advanced Operations
Zooming with a Scroll Wheel Mouse
Centering the Point of View
Perspective Adjustment (Field of View)