View Single Post
  #12  
Old 06-05-2009, 05:49 PM
ausastronomer (John Bambury)
Registered User

ausastronomer is offline
 
Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
Posts: 2,620
Quote:
Originally Posted by rmcpb View Post
(baffles need to be different diameters along the tube).

Cheers
Rob,

That's not totally correct.

If you want to be totally anal about it you can certainly size the aperture of each baffle to be just larger than the diameter of the light cone at each baffle point. However, the main objective of anular baffles is to reduce internally reflected light by breaking down the "angles of incidence" along the tube periphery. A few annular baffles appropriately placed and sized to the maximum aperture of the light cone with a little clearance effectively achieves this. I have a fully flocked tube as well as 3 annular baffles in my 10" tubed newtonian, one either side of the focuser drawtube and one just above the primary mirror and they work beautifully. The scope gives "refractor like" views. The spotlight self adhesive black felt works beautifully as a flocking material. Warning: Cut the strips before you peel the backing off.

Cheers,
John B
Reply With Quote