Telescopes

28 inch alt-az  Newtonian  

 
Cover photo of Amateur Astronomy, issue #50. This is an 18 point, low profile floatation cell for the 28 inch diameter, 2 inch thick Pyrex primary mirror. The edge supports are two wiffle trees. However, the main design feature is that the entire mirror cell is moved by the collimation bolts, not just the mirror, so edge stresses don't build up during collimation. Thanks to Dan Gray for this design.
 
 

8 inch f/4 "Springsonian", a regular Newotinan Dob with a fixed height eyepiece
 
 
 The detachable observing hood is the most important baffle - it keeps stray light from getting to your eye. This is especially helpful when observing from an urban backyard like mine, but is still quite useful from a dark sky site.
 
 
 
 

 13.1 inch String scope, f/4.4 Newtonian, with spring counterweight

String scope made of Alucobond and foldable tent poles, designed to break down and fit into its rocker box for airline travel. Alucobond is a material made for cladding the outside of building and is two very thin layers of aluminum bonded to a central layer of engineering plastic. Great stuff to work with but it's more expensive than plywood. It's big pluses for telescope making is that its impervious to the elements and is very flat and stiff material.

The scope also uses a spring counterweight to counteract the low center of gravity. 

 

 At the 2005 Shingletown Star Party - why is this man so happy?


 

There are two main ideas that led to this design -

Constant height eyepiece, and the entire scope is easily moved on wheels.  


Completed in May 2007, just in time to go to Hawaii.  The assembled scope weighs 36 pounds, but as light as that is for a 13 inch scope, it's still a lot of weight to lug through airports. Next time I'll find a piece of luggage with wheels that it will fit into.

 

 

 

 

 

 

 

 

Links to more information about the 28 inch scope:
 
 
  
 
 
 
 
 
 
 

Links for more information about the 8 inch scope:
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 If you want to know the secrets of making a successful string scope, please read Dan's page carefully! This is important because of the stresses the strings place on the mirror box - I know because I did a poor job and my mirror box flexes under the load and I need to rebuild it before the next trip...

Hey, it works - for the most part. Here it is a week after completion relaxing by the pool on the Big Island of Hawaii. The light baffle has been added opposite the focuser.
 
 
 
 
 

This page has a photo and description of the other telescopes I've built or bought since 1969.
 
I've built several equatorial platforms, two for myself and four others helping friends.