Telrad dew cap against fogging of the viewing window

On a cold, humid evening, the slanted window of your Telrad is often the first to get covered, because it is open towards the sky. A Telrad dew cap screens the window, so it cools down less quickly and the dew stays on longer. Also, streetlamp or neighbor light is less visible.

The cap is made for the Telrad viewfinder and covers over the viewfinder window. You can find more ways to prevent fog from forming at Dew prevention for your telescope.

A dew cap prevents fogging, but does not always completely prevent it. Therefore, set it on at the beginning of the evening, because a window that has already fogged up will not clear up immediately. Let the cap dry after use before storing it.

On very wet nights you can use it the dew heating for the Telrad in applications controlled by a regulator for fog lights.