This image comparison shows a view through a Hazard-Avoidance camera on NASA's Curiosity rover before and after the clear dust cover was removed. Both images were taken by a camera at the front of the rover. Mount Sharp, the mission's ultimate destination, looms ahead.
The view on the left, with the dust cover on, is one quarter of full resolution, while the view on the right is full resolution. Full-resolution images taken with the dust cover still on are not available at this time.
The only other instrument on Curiosity with a dust cover is the Mars Hand Lens Imager (or MAHLI), located on the rover's arm. In this case, the dust cover is not removed but will be opened when needed. This way, the instrument is protected from dust that may be generated from other tools on the rover's arm, in addition to wind-blown dust.