My amateur telescope making page

The "Deep Space Scope" Design

Home | Astronomy | DS-3 | Baffling and Contrast


Baffling is done to telescopes to keep as much stray light as possible from reaching the user's eyepiece and eye.  It generally includes blocking stray light paths and making the inside of a telescope be flat black.  A poorly baffled or not baffled telescope will have a brighter background at the eyepiece.  A well baffled telescope will have a darker background at the eyepiece.

Baffling 101

After wondering where to begin, I reread the article on baffling a reflector in Sky and Telescope, April 2001.  This article, titled "Newtonian Baffling Made Easy" by Gary Seronik, is so good and complete that I will recommend that any ATM get a copy.  In a nutshell, Gary states that baffling is a simple matter of looking into the focuser of a telescope, and making sure that the only light you can see is coming from the primary mirror.  My way of saying this is that anything that isn't coal mine black (with the exception of the mirrors aiming at the stars) should be, well ... coal mine black.  This includes, in order:
DS-3, with baffling, looks like this:
Deep Space 3, Dark secondary Deep Space 3, Back baffleDeep Space 3, Short shroud
Various techniques that were used on DS-3.

Engineering and testing (background reading)

Originally, DS-3 used very poor baffling.  I originally just used a piece of black plastic as a back shield for the secondary.  Shiny black plastic.  With white trusses.  And a white rim of raw glass around the secondary mirror.  Ugh.  After a great deal of testing and being very dissatisfied with my results, I decided that any telescope should be evaluated under three conditions:

Baffling DS-3 - what works and what didn't

Generally, a light weight dob like DS-3 ends up being a compromise of conflicting goals.  Here was MY solution, which is currently working quite well.