Unless you do your stargazing in a desert you will experience perfectly good visability being ruined by dew condensing on your telescope. It is important to have a dew heater strap to avoid moisture on the telescope lens or mirror. Heater straps need a controller to regulate the temperature by thermostat or variable resister. Additionally, you can also use a lens shade (or dew cap) which reduces the amount of moisture build up on the corrector plate of an SCT or objective lens of a refractor. Lens shades are also ideal for preventing stray light, improving contrast and images overall. See our range below or contact us if we do not have what you are looking for.