What does the half gain angle of a projector screen mean?
The half gain angle is the area of the room for which the projected image produces the fullest spectrum view. This area is roughly in the shape of a cone with its point toward the center of the screen. Viewing cones are described by defining the degree radius formed by the outer limits of the cone. Higher gain reflective screens produce narrower viewing cones, while matte surfaces produce a broader viewing cone. Half gain angle is only ½ of the viewing cone. Multiply the half gain angle by two to get the total viewing cone. One of the most often quoted properties in a home theater screen is the gain. This is a measure of reflectivity of light compared to a screen coated with magnesium carbonate or titanium dioxide, when the measurement is taken for light targeted and reflected perpendicular to the screen. Titanium dioxide is a bright white colour, but greater gains can be accomplished with materials that reflect more of the light parallel to projection axis and less off-axis. Frequentl
