Re: [ATM] New 16" telescope design

["John Sherman" <atm@mail.johnspics.com>]

Hi Tom!

>Also, why use a shroud?

1) To protect my mirrors from dust, pollen, fingerprints, and bugs.

2) To keep the wind from getting to my spider and vibrating it.

3) To keep my body heat out of the light path.

4) To keep light from shining on the inside of the UTA where
   the eyepiece can see it. 

5) I'll think of it later, no doubt..  :^)


Sure, I've heard of Heron's law. But very few surfaces are perfectly smooth, so the angle of reflection is not always what you'd expect, light can reflect off into lots of directions. And not all surfaces are perfectly reflective or absorptive, most surfaces scatter light in all directions (esp. flat black paint!). Best to keep ALL unwanted light away from the inside of the scope, that way you can be sure your field is as dark as possible. Since the planets and even the Milky Way leave visible shadows, they are termed "light pollution", so it doesn't matter how dark your observing area is. 

Bring your scope on out this way, and we'll compare!

Good enuf?

John







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