An interesting way to fix a dew cap

Typically, a layer of felt or velour is placed between the dew shield and the lens cell. In some models, the dew shield is secured with a screw to prevent it from slipping back near the zenith.

In the Kson ED-APOs, a spring pressure is exerted via a wire, which presses against the inside of the dew shield via four rollers (shown here in white).

www.teleskop-spezialisten.de/shop/Dienstleistung-Service:::10.html