Dew shield

A Dew Shield is a device used to prevent moisture or condensation buildup on the lens of a camera or telescope collector during cool night observations. The Dew Shield either shades the lens or provides a small about of warm air directly in front of the lens or collector to prevent dew from collecting on the element.

Some Dew Shields work by using a heating element that keeps the objective lens warm enough to keep the dew from collecting.