I'm contemplating knocking up a dew shield for my 10" dob. I have a dew heater for the secondary mirror and I'm thinking this will help retain the slightly warmer air around the front of the scope and discourage any dew formation inside the tube?
The materials I'm using are freebies from work - no real cost involved.
I made one for my 12" dob and it works ok, used a black camper mat and hold it on with a velcro strap. I run my mirror fan constantly in winter so dew isn't a problem usually anyway but the shield might help. I have stayed away from dew heaters so far.
Sounds like they help a little... my dob doesn't have the fan yet, so in leiu of that I'll try my experimental dew shield out - it's not pretty
If it proves to be a winner, I'll see what I can do about refining it!
One of the guys at the Pony Club had a shield on his Dob. But he had it there to improve the contrast. I am going to make one up for mine as well and see if the contrast improves. With the secondary heater working, I have never had a dew problem, even with moisture dripping off the tube. You might as well build one, I figure every little thing you do improves the performance.
