I shoot a lot of pictures in the open ocean, the eye cup helps keep the wind from getting between me and the camera's eye piece and keeps me from getting teers or dust in my eye. The hard part was that I wanted this for my D200 and D70 cameras, and finding the right adapter to make it work was difficult. I finally used the Nikon Eyepiece adapter and super glued the rubber eye cap to it, and that works great.