I have a rain sensor on my observatory that uses a commercial water leak detector. Two wet-leaf sensors on the roof cause the detector module to send a signal to the dome controller to close up. It works well.
Too well, in fact. The wet-leaf sensors do not distinguish between rain and dew. So even though I use a solid-tube Newtonian in a dome, about the most dew-proof configuration possible, my sessions get cut short by a little bit of dew. (The good news is that I know I am well-protected against rain, but it is annoying.)
So, I am looking for ideas for a sensor that would detect rain but not dew. Anyone have a creative solution?