[Shiraz (Ray)]

Originally Posted by Paul Haese

Hi Ray,

I have had this problem at Clayton every winter since I have had an observatory there.

Have you considered having some fans on your scope running all night? My RC has fans which run all night and that keeps the dew off the primary. The secondary has a dew heater.

I typically run the fans about a couple of hours prior to imaging and opening the scope to the night air.

This seems to work well in keeping the problem at bay.

thanks Paul. I don't have dew problems when imaging - I also run fans and it seems to work well enough in keeping the optics dry while imaging. But it all dews up when the fans stop, the roof is closed and the sun comes up - getting dripping wet cannot be good for anything.

Originally Posted by gregbradley

Leave the roof open for longer until it warms up from the morning sun. Of course if the weather looks stable.

I haven't seen that in my observatory but you are a long way south of where I am so I assume cooler temps there.

Greg.

thanks Greg. Leaving the roof open is an option, but I am often away during the day, so there are times when it must be locked up early. I was surprised how wet it was at 10am, since I do not have a problem with dew while imaging. It didn't occur to me that dew might be problem during the day, when everything was shut down and the sun was up. Nightime temps have been 5-6C, so it isn't really cold - less than a km to the sea though, so lots of dew in the obs after a night of imaging.