Rainband for 12 inch telescopes (305 mm) | Astrozap

The larger the front glass, the more surface area there is where dew can fall. This Astrozap dewband for a 12-inch telescope, such as a 305 mm Schmidt-Cassegrain, keeps that glass just above the dew point.

You place the band around the tube, close to the corrector plate or the front glass, and connect it to a dew point regulator. Large Schmidt-Cassegrain telescopes have a corrector plate that looks straight at the cold sky, and moisture quickly accumulates there.

A dew cap slows down the cooling, the band does the rest. Be sure to have enough power for the entire session, especially if you also connect your mounting and camera to the same battery. A battery like the Celestron PowerTank Lithium LT has 73.3 Wh; just calculate whether that is enough for your setup.

For a telescope of 280 mm, there is the band for 11 inch telescopes.