Dell 1800MP Owner's Manual page 76

Zoom Lens— Lens with a variable focal length that allows operator to move the
view in or out making the image smaller or larger.
Zoom Lens Ratio— Is the ratio between the smallest and largest image a lens can
projector from a fixed distance. For example, a 1.4:1 zoom lens ratio means that a
10 foot image without zoom would be a 14 foot image with full zoom.
76 Glossary