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Celestron tube vents
Yes, indeed I did want to get something off my chest. I fully appreciate what you are saying.
In my observatory, my sessions are normally quite short and I don't know that I ever had dew on the outside of the corrector plate. True, I sometimes use a dew shield. If I have several events to time in an evening, I might either cover the top of the tube between them or roll back the roof to cover it. I live on the top of a ridge and there is generally some movement of air. Dew is not a problem.
I remember many years ago (say 1980), once having dew on the mirror of the 16" pointing vertically, imaging the lagoon nebula... but that was all.
So I was b.......annoyed when the inside of my 14" corrector plate started fogging when the other SCT's simply did not. Hence my statements.
I made a conscious decision not to purchase the EDGE for the reasons I stated. Certainly for objects in the centre of the field or close to it, there should be no difference. Where the EDGE shines is the flat field with near perfect images right to the edges. As I said, these images can get pretty ugly with a standard SCT near the field edge unless you use a corrector...
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