BRIGHTNESS FACTOR

The correction factor to be applied to the projector brightness based on the zoom.

The brightness factor is a way of describing how the brightness changes as a zoom lens moves from the shortest to the longest zoom. In a zoom lens, the brightness is highest at the shortest zoom and lowest at longest zoom.

Projector brightness specifications are normally measured with the lens at medium zoom. This means that at medium zoom, the brightness factor is 1. As you move towards the shorter end on the zoom, the brightness increases so you have a brightness factor greater than 1. As you move towards the longer end of the zoom the brightness decreases so you have a brightness factor less than 1.

The brightness factor is directly driven by the F-Stop range of the lens. The closer the F-Stop values at each end of the lens, the lower the rate of change of the brightness factor.