From: "Bob May" 
To: "atmlist" 
Reply-To: "Bob May" 


Dennis, I'd use that tube to make a larger tube of wood, fiberglass or
other good material and gain some additional diameter to the tube. A nice
project would be to get several different woods and make strips of the wood
the length of the tube about 3/4" wide (calculate out how many strips
of a particular width will go around the tube and then figure the angle
needed to make them mate without gaps - a hexagonal tube wants edges cut at
30 deg.) and use the sonotube as a form for the real tube you will use.
After making a larger tube the installation of baffles will make the
scope's performance supurb for light control. That 5.5" tube is really
too small as the edge of the tube will limit the amount of light that will
be coming in from off-axis objects.  Go find Newt2.5 and run the stuff that
you have through the program to see what is going on.  Many of us use a
tube that is at least 2" larger in diameter than the mirror just to
make sure that the tube doesn't obstruct the light coming in.
Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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