Do the right thing about dew!Astro Zap's 5SE lens shade/dew cap is a tube, of approximately the same diameter as your telescope's tube. It's designed to fit on the front end of the telescope to reduce the amount of dew that builds up on the corrector plate, ruining your view and possibly your scope. At the same time, it serves as a lens shade, preventing stray light from falling on the corrector plate. This also greatly improves the view. Astro Zap's lens shade/dew cap: it's what to do about dew (and bright sunlight)!