The firmware upgrade will give your H4D-40 or H4D-50 a digital spirit level function. The feature will be visible both in the viewfinder and on the rear display. This function is easily activated with a simple press of a button or via any of the programmable user buttons and allows accurate alignment and level readings even when using the camera handheld. The spirit level reads both the vertical and horizontal positions (pitch and roll) of the camera and can be calibrated by the user to suit any situation (predetermined angle or tilt, etc.)