My amateur telescope making page

The Up-sized "Deep Space Scope" Design

Home | Astronomy | DS-4

DS-3 has ended up being such a successful telescope that I decided to create a larger homemade telescope using the same ultralight design.  This web page holds the results of these efforts. 

The original design and requirements page is located at DS-4 Design and brainstorming notes

My latest project is a 12" travel telescope. DS-Trill  

I also decided that this web page would generally just describe WHAT I did to make this lightweight telescope, not HOW I did it.  Weights and dimensions are near the bottom of this page.

I added a conclusions and results section at the bottom of this web page.

To see how to create a "Deep Space Scope", see my DS-3 Deep Space Scope Design page.   Although the design is the same, I would HIGHLY recommend going for a 16".  It is worth the extra cost, and isn't much more work.

I did decide to mainly use one version of wood - 1/2 inch apple plywood.  (Apple plywood has many thin layers.  It is NOT necessarily made out of Apple plywood.)  I rejected composites because I felt that it wouldn't help much.  The sides, top,  and bottom of the mirror box needed strength, and the front and back (good candidates for composite) didn't add up to much weight.  The secondary ring is already so light that it wasn't worth dealing with composites.  The ground board is a good candidate, but is already so light that it doesn't matter.

Clicking on any picture will give a larger version.


Deep Space 4, the Telescope
Here is DS-4 at Datil Well, a dark site in New Mexico. The file that you download if you click on the picture is very large, but shows off how the scope looks.
Deep Space 4, the Telescope

Here is the finished product. The strange looking guy behind the scope is me.  Notice how small the mirror box, ground board and secondary cage is.  The bearings come off to fit in the trunk of a car.  The trusses lay beside the front seat passenger.  I have cut off the sides of the rocker box by 1", and tightened the mirror screws (thus lowering the mirror a bit) and cut the trusses shorter by 1".  I also rotated the focuser a bit towards the side of the telescope.  Thus, I have shortened the scope enough that I can do all of my observing from the ground.  Yay!!! I am 6' 0" (minus a fraction of an inch) tall.

Deep Space 4, the Telescope
Another view of DS-4.  A mirror cover is in place.

Deep Space 4, the Telescope
Side view of DS-4. The center of the bearings is the center of gravity of the optical tube. Notice the 2" feather touch focuser, which adds weight to the top of the scope, thus increasing the size of the bearings. The bearings come off with 2 screws per side for easy transport.

Deep Space 4, the Telescope
Jim Lawrence - master telescope craftsman at work.  Jim originally built the "Deep Space" design scope that I used as a template.  Jim has since built a beautiful 12" binary telescope that never stops amazing fellow "cyclops mode" observers.  This is the mirror box for my 16", with Jim doing a bit of cleanup sanding.

Deep Space 4, the Telescope
Picture of DS-4.  Obviously an open truss telescope.  They eyepiece height ended up being about 5'10" high at zenith.  Motion is very smooth.  The heaviest piece is 40 lbs, and the total scope weighs about 60 lbs (not counting the baffle).  Setup time is about 10 to 15 minutes. 

Deep Space 4, the Telescope
Another picture of the scope.  Balance ended up being right on, and no weights have to be added to the mirror box.  I made the attachment points for the main bearings fit into one of three sets of holes in the mirror box - thus allowing me to "field change" the balance.  Here the bearings are attached to the middle attachment holes.  I have since cut off the sides of the rocker box 1", thus lowering the scope by that 1".

Deep Space 4, the Telescope
DS-4 was designed to fit in a hatchback.  Thus, the size of the rocker box, secondary cage and total packed height are important.  This whole assembly - without the bearings attached - fits in the trunk of my Honda Del Sol.  A few notes:

Deep Space 4, the Telescope
Here is the scope stored in the hatchback position.  Although the bearings are taller than the scope, they aren't that tall.  Notice that the stored position for the scope is rotated 90 degrees from it's "in use" position.  This allows it to sit a few inches lower.

Deep Space 4, the Telescope
Mirror cell.  At the heart of any telescope is a good mirror cell.  My mirror is 1 5/8" thick and 16" in diameter.  It was purchased from a local ATM builder that had lost interest.  It is a Meade mirror, and appears to be excellent.
The mirror cell is 6 disks held on two arms.  The mirror is attached to the mirror using double sided sticky tape.

Deep Space 4, the Telescope
The mirror box and mirror.  I put the truss holes in the corners to create a "cage" for the shroud.  The mirror box top is 1/2" thick, with two 1/2" thick triangles glued into the corners.  The truss holes are 1" deep, and the trusses are held in place by friction and torque only.  Each hole was then strengthened using CA (Superglue).  The mirror is about 3/8" below the level of the top of the mirror box.

Deep Space 4, the Telescope
Underside of the mirror box.  Notice that the mirror is still in the box, and is hanging from the mirror cell and double sided sticky tape.  I also decided to put one big hole in the box for cooling, with the idea that I could add a fan here later.  So far, this has not ended up being necessary.

Deep Space 4, the Telescope
Inside of the mirror box.  Notice the embedding nuts in the sides of the mirror box.  Also notice the additional wood wedges in the corners to add strength to the trusses.

Deep Space 4, the Telescope
Secondary cage.  A few things to notice:

Deep Space 4, the Telescope
Another view of the secondary "cage". This one is down the main axis of the scope. Notice that the wires do not radiate directly from the center of the axis, but are actually offset. Surprisingly, this does not change defraction spikes at all.  So much for theoretical ideas.  

Deep Space 4, the Telescope
Spider.  Here you can see how the spider stack is created.  So far, I am thrilled with home grown wire spiders.  The secondary mirror is 3.1" wide, and comes from AstroSystems.

Deep Space 4, the Telescope
Truss ends.  The trusses have been covered with wide electrical tape.
Total telescope:

Weight - Actuals

Mirror, mirror box, no bearings
35.2 lbs
Mirror, mirror box and bearings 40 lbs
7 lbs
Secondary cage
4.1 lbs
Rocker box with base
11 lbs
Total Telescope weight
62.1 lbs
Total weight of the OTA (Optical Tube Assembly)
51.1 lbs
Total weight of heaviest item (mirror and mirror box)
35.2 lbs


Height of eyepiece at zenith
70", 5'10"
Size of mirror box and base, no secondary cage, no bearings
Size of mirror box and base, secondary, no bearings 20x18x17"
Size of mirror box and base, secondary, and bearings 20x18x25"
Length of trusses

Primary Mirror
Second hand Meade 16", f4.5 (new condition)
Secondary Mirror
Astromart 3.1"
Starlight Feathertouch, 2" barrel, brake, tube compression ring
 Ebony star / misc
1/2" Plywood
Cabinet shop, includes cuts
Metal Supermarket (cost approximate)
Misc parts
Home Depot/ Lowes / True Value Hardware (cost approximate)
Home Depot / Lowes


Results - Did it work?
DS-4 has ended up being wildly successful.  It is a telescope that rivals any other scope that I have tried in it's size, always draws a crowd, and easily fits in my car. It is also easy to carry and doesn't take up much space for storage. Images are fabulous, and it is easy to use. It was also reasonably easy to make, and fairly cheap.

Results - star tests

Things that still need to be done