suitable for medium-sized screens
Between 2500 and 4000 lm is suitable for medium-sized screens with some ambient light or dimmed light. Over 4000 lm is appropriate for very large screens in a large room with no lighting control. Projected image size is important; because the total amount of light does not change, as size increases, brightness decreases. Image sizes are typically measured in linear terms, diagonally, obscuring the fact that larger images require much more light.