Zoom Lens Ratio

The ratio between the smallest and largest image a lens can project from a fixed distance. For example, a 1.4:1 zoom lens ratio means that a 10 foot diagonal image at 15 feet with no zoom would still be a 10 foot image at 21 feet at maximum zoom (15 x 1.4 = 21 feet). Conversely, a 10 foot image without zoom would be a 14 foot image with full zoom.

The higher the zoom ratio, the less light output.