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Foggy scope

  1. Aug 14, 2003 #1
    I tried to check out mars and the moon the other night with my new orion dob.. but it was so humid that the scope got all fogged up... is this just something you have to live with? Are nights of high humidity just bad nights to go observing?
  2. jcsd
  3. Aug 14, 2003 #2
    if you take a scope out of a A/Ced house or car in to warmer night air it will fog in a hi H envro.
    if you let the scope warm up this will not be as big a problem, by leaving it out of the cooler places or turn off the car A/C unless dew actively is falling at the time.
  4. Aug 15, 2003 #3


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    My scope manual says to leave it outside with the lens caps on for half an hour to let the temp equalize. Even without condensation, temperature variations will lower the resolution of the scope.

    I used to just crack open my window and view from there though.
  5. Aug 15, 2003 #4
    last night i put the scope in the car about 45 min before we went out... it worked much better.. also the humidity wasnt AS bad last night... first thing i pointed at was the moon.. awesome to see it with so much detail... obviously the easiest thing to find in the sky.. mars we found with ease, but I was a little disappointed because I thought we would get a little more detail with it... it seemed less red through the scope and not all that much bigger than the naked eye... maybe we were doing something wrong.. because i tried using different eyepieces to increase the view.. but still couldn't see it any better
  6. Aug 15, 2003 #5


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    If that was the case, see if the scope came with detailed collimation (alignment) instructions. That could be THE problem, and changing eyepieces should have definitely made an obvious difference.

    What kind of scope, and focal length, and what focal length eyepieces are you using??
  7. Aug 18, 2003 #6


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    This is key. This same time can also be used to allow your eyes to dark-adapt (takes ~15 minutes).
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