What is the difference between optical and digital keystone?
The optical keystone angle is the angle between the optical axis and the center of the projected image. This varies by some degrees and is dependent of the position of the zoom lens. This angle is actually a fixed angle and can only be “changed” by turning the zoom lens Digital keystoning gives you the possibility to have a correct square image, even when the image is thrown upwards in desktop mode or downwards in ceiling mode. This is achieved by an asymmetrical scaling, providing a square projected image when/if the projection lens is tilted in comparison with the projection screen.
