Dew caps

[Ganymede12]

Why don't reflector telescopes have dew caps. Does dew not form on mirrors or do they ruin the performance of the scope somehow?

[brantuk]

Errrmmm... reflectors do have dew caps which come off during a session - but newtonians have their mirrors right down inside the tube so usually don't dew up. If they do you can rig a fan behind them to keep the air moving to prevent dew - but it's not allways necessary. Mak's and Sct's are enclosed so the mirrors are even more protected from dew on those.