Newtonian PV value and good honnest dust

[karlfunki]

I peer down my dob at the 1/8 PV primary and I wonder to my self - "what effect does that dust have, does it push be back to 1/6, 1/4, 1/2"? Its only a very light covering, but its there, the scope is 5 years old and while its been covered stuff has gotten in.

Specifically, I am considering an upgrade (from 10 - 14 or perhaps 16, or maybe...) and I am trying to work out what to get for my new optics.

Do I blow the extra cash on upgraded optics when I know there *will* be a fine layer of dust within a few months, and I am too scared to clean it.

Cheers,

Karl

[dweller25]

A little dust will not be a problem.

There are loads of guides on the net for how to clean a mirror for when you need to. It's not a big job and the coatings are VERY tough.

[barkis]

Dust may cause a little light loss, but only that. The mirrors figure of revolution will remain un diminished. The only thing that will affect it, is temperature. So cooldown time is desirable, unless your objective is made from an exotic glass such as Zerodur, or Cervit, with almost no thermal expansion.

Ron.