Condensation on eyepieces

The heating pads sound like a good idea.

Anyone any tips on avoiding condensation DURING the night?

A dew shield will help on your main OTAand if necessary, viewfinder. Dewshields also help reduce stray light from neighbours or adjacent street lights. However, a dewshield will only delay the onset of condensation formation.

You can use a hairdrier WITH CARE. Preferably just use the cold setting (ie no heat). If you heat any optical surface too much you can put it permanently out of shape or even crack it. Additionally, when marginally heated, your view through the optics will deteriorate and you can induce tube currents. For visual observing, these effects will hardly be noticeable.

The best solution is a dew heater controller and heating bands or pads. The controller delivers an appropriate amount of power to the dewband to keep the temperature of the surface just above the dewpoint. Dewbands can be obtained in all shapes and sizes to fit eyepieces, corrector lenses, mirrors etc.

You can make your own controller or purchase one of the number of brands out there. They would usually be powered by a 12V battery so factor that into the total cost too.

HTH

Dave

Last week I was in the OAM ( Observatori Astronomic de Mallorca) for university project work and the humidity there is quite high so dew is a major problem in the early hours of the morning. The solution there was a hairdryer. Each dome was supplied with a hairdryer.

I must admit though that this sounded quite funny one night was around 2am you heard hairdryers from several domes ...sounded like a beauty salon

Simple but effective way to keep eyepieces clear of dew is to put them in bank coin bags and keep them in your nice warm pocket (capped of course), when not in use. Then when you take them out they are nice and toasty. If an eyepiece dews during use, hold it tight in your hand for a few minutes to warm it up.