ATM Baffling a newt - street light tests

[Krajci Tom Det5 57 Wg <Tom.Krajci@barksdale.af.mil>]

I've been taking Suiter, et al's advice to baffle various parts of my 10
inch f/7 to reduce veiling glare.  (See http://interoz.com/usr/suiter/  "Top
Ten ways of improving Newtonian telescope optics")   For the most part it's
been very helpful, but one baffle doesn't look like it's going to help me
much:  the "moon shadow" baffle on the main tube, opposite the focuser, and
above the secondary.  It's purpose is to shadow the tube wall so that the
nearby moon doesn't light up the part of the tube that is visible from the
point of view of the focuser.  (Yes, baffling the focuser tube also helps to
partially block the view to this part of the main tube, but my low profile 1
1/4" focuser's baffling can not be as effective as a higher profile, 2"
focuser.)

Since I didn't have a full moon handy last night I used a nearby streelight
in it's place.  I visually examined the amount of veiling glare visible at
the eyepiece at various pointing angles near to the streetlight.  (This
analysis is qualitative only. . .I took out the eyepiece and looked into the
focuser. . .I looked to see how bright the opposite tube wall and spider
parts were compared to the brightness of the mirror/sky background.)

To test Suiter's recommended "moon shadow" baffle I had to shift the scope
about 2/3 degree away from the streetlight. . .just enough to get the
streetlight's image beyond the edge of my focuser baffle.  (But the
streelight was still shining on the main mirror. . .I'd need a VERY long
tube extension to solve this problem!)  With my eyes dark adapted, yes, I
could faintly see the streetlight illuminating the far side of the tube. .
.but. . .that amount of light reaching my eye was far, far less than the
light scattering off the mirror coating due to dust buildup (but this mirror
coating is only two months old and I keep the scope indoors/capped, so
there's not much dust), scattering from the coating itself (maybe, but how
can I measure this effect by itself?), or incomplete polish (doubt it, the
glass looked very good to me before coating using the laser pointer scatter
test).  The amount of streetlight light scattered off the main mirror was so
great that it was very hard for me to even see/distinguish the far side of
the tube wall.  That tube wall was awful dark and probably contributed a
very small fraction to veiling glare compared to scattering off the main
mirror.  (My tube is covered in flocking paper and the light
shield/extension extends 24 inches beyond my focuser.  This scope is pretty
well baffled and gives contrasty views and very good comments at star
parties.)

This analysis was not quantitative, but I'm wondering who else has done
streetlight tests like this.  What results have you gotten?  Do I just have
a dusty/high scatter mirror, or are my results typical?  (I don't think my
mirror is higher than normal scatter.  It's clean and was well polished.)

Maybe this just means I'm doing a good job troubleshooting my scope's
baffling needs and getting close to an optimum setup?

Capt (Major select) Tom Krajci
B-52 Intelligence Officer
http://spur.barksdale.af.mil