A lens (10) and its mounting arrangement (12) for providing the operator of a construction vehicle (32) with an enhanced view of an area (34) invaded by a swinging boom or other hazardous machinery mounted on the vehicle. The lens (10) is a combination of a prism and a concave lens. The prism diverts the operator's view downwards, and the concave lens covers a wider area than otherwise. The mounting arrangement (12) enables the lens (10) to be mounted on a standard preexisting part (30) of the vehicle (32) without modification other than providing screw holes. The operator can easily see to avoid colliding with persons or other hazards within the operating area.
