How do I deal with dew when using my telescope?
shish2kabob asked:
I have an Orion Skyquest XT8 Dobsonian telescope :
http://eridanusoptics.com/store/images//telescopes/dobsonians/OR9707.jpg
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I have an Orion Skyquest XT8 Dobsonian telescope :
http://eridanusoptics.com/store/images//telescopes/dobsonians/OR9707.jpg
i have heard using a hair dryer works but i do not think it will reach down the optical tube down to the mirror. i also don’t have a portable one. will putting plastic wrap over the front of the tube work to reduce the dew? will it affect the image that i see?
February 17th, 2010 at 6:28 am
You can buy something called a Dew Heater which wraps around the outside of your tube at the level of the mirror and it helps to keep the mirror warm and dry.
In a pinch you can also take those chemical hand warmers and using a big rubber band or bunji cords you can place them all along the outside of the tube again at the mirror level to keep the mirror warm too.
Do not try the plastic wrap. Yes it will distort the images plus the dew will form on the plastic.
Orion sells Dew Heaters B.
February 17th, 2010 at 6:51 am
Dew on the finder and the eyepieces can be an issue, but is your primary really dewing up? This isn’t usually an issue with Newtonian scopes. Viola At Neon
February 19th, 2010 at 11:56 pm
Dew is almost never a problem on the primary of a solid-tube Newtonian. The chance of dew forming at the bottom of a 4-foot tube is virtually nil. Dew sometimes forms on the secondary, but even this is rare, because the mirror is facing away from the sky. Dew is more of a problem with truss-tube Dobs, though I’ve only once been shut down by dew in eight years.
Refractors and cats are where dew becomes a serious problem. Geoff G