I also think it may be inversely proportional to the age of the instrument.
Example 1: Bought my Celestron C5 new- clouds for two weeks (very expensive 17 years ago)
Example 2: Got my 'new' 30 year old 17.5" Odyssey II, no clouds for a month!
Obviously the 'moistions' had worn out after 30years.
Mind you, do "they" also add moistions to paint? I'm painting the rebuild of the old dob, OOOOOOO.....
