My amateur telescope making page

The "Deep Space Scope" Design

Results - abstract

Results - Details, working top to bottom

• Setup/ tear down - Setup takes under 5 minutes.  1) Pull scope out of the car, place where it goes.  2) Remove secondary cage.  3) Drop in trusses.  4) Attach secondary to trusses. 5) Columnate ( 6 Possibly attach baffling.)  7) Attach Quickfinder.  Tear down is also under 5 minutes.
  
• Quickfinder - has ended up working very well.  Objects are easy to find.  The quickfinder is out of the way as placed on this telescope.
• 2" KineOptics Helical focuser - This focuser is not bad to use.  It goes from totally in to totally out in about 1 3/4 turn.  It moves from totally in to totally out in about 1 1/2 inches.  If you are careful, it still has enough precision to make it easy to focus.  I do wish it had finer resolution.  Workmanship is fabulous.  It is quite light weight, although I am not sure exactly what it weighs.
• Upper "cage" design.  This has worked out fairly well.  I like the design of my DS-4 scope better.  The 1/2" plywood ring is plenty stiff, and very light.  The wire spider has generally worked out very well.  The only four things that have been issues with the spider are: 1) the nuts on the brass rods sometimes loosen.  Fixed with some locktite.  2) The wire, as it runs through the brass rods, sometimes moves if you pull on it, thus messing up columnation between observing sessions.  Not yet done, but solution - push a toothpick in the hole in the brass rod, and put a drop of CA glue on it.  The wire will never slip again.  3) As you adjust the columnation screws on the secondary, the whole secondary mount rotates in space, stretching the wires.  Until you let go again, letting the wires spring back to their original position, you have no idea if you went enough, or even if you are turning in the right direction.  Makes adjustments take longer.  Defraction spikes that do exist are in a pretty hexagonal pattern.  Conclusion - after getting the secondary columnated, this unconventional upper cage works quite well.  If I ever rebuild the secondary cage, I will probably use a DS-4 design.  See "Astronomy" above, then select "DS-4.
• Trusses - 3/4" trusses are working very well.  There is no backlash at all as you are moving the scope.  Columnation is rock solid, no matter what the orientation of the scope.  (See mirror cell below.)  Adding wide black electrician's tape has helped with looks, baffling, and to make it more comfortable to move the scope.  I find that I generally move the scope by grabbing a truss and dragging it around.  The truss attachments have worked out very well.  They never slip, are easy to make, and have held up well.  When putting the scope together, it does take a few minutes and a bit of experience to get the tops of the truss tubes lined up properly.  One issue that I am working on is where to place the three upper truss connection nuts when I am setting up/ tearing down.  They keep getting put in a pocket and forgotten.  One option is to install three very small screwed rods hanging off of the finder plate.
  
• Mirror box - This has worked out very well.  Relatively light weight, indestructible, and a bit of a dust barrier.
• Altitude bearings - These are right at the edge of not being sticky enough.  Taking a 1 lb eyepiece on/off the scope makes it go from almost too heavy to almost too light.  I have some weights I take with me to help balance the upper cage (which is too light).  Movement is smooth and precise.
• Mirror cell - The mirror cell has worked like a charm.  It stays in columnation no matter what the orientation. I have driven the scope up to 381 power (8mm Orion Superwide Lanthanum with a 2X Televue BIG barlow), and could see NO astigmatism at all, no matter what the orientation.  The mirror cell also probably cools the mirror down about as fast as is possible without a fan.
• Mirror cooling - The Aire rings around stars never did stop slowly waving, making me believe that I have surface layers on the mirror.  Next project - a fan that will be velcro'd onto the top of the mirror box.
• Rocker box and baseboard.  These have worked perfectly well, giving NO backlash (or bending) when adjusting the scope.  I am becoming suspicious that I actually over did the stiffing of the rocker box, and thus wasted weight.  Next time, I won't add the stiffening boards until proven that I need them.
• Vibration - The scope has no vibrational issues at all, unless there is a pretty strong wind.  Even then, this scope is generally the last truss telescope still standing at the end of the night.
• Baffling - See the section on baffling here.
  
• Build cost - was under $1000.  (I didn't keep receipts, so don't know how much under $1000 it was.)
  

Results - star tests

• I am a bit of a new observer with really good equipment, so am probably not the best person to give a final rating to this scope.  But, since I am all I have, here goes.
• The scope is sensitive to Columnation.  When columnation is right on, stars are pinpoints using any eyepiece that I have, including my 8mm.  With exceptional seeing, using a 2x barlow and my 8mm eyepieces (giving 4mm) works acceptably well with Saturn.
  
• With good seeing, the 6 stars of the trapezium are obvious, and are viewable with direct vision.
• The double double stars in Lira are splittable, and I can see a thin dark lane between them.
• I could not see the center star of the Ring nebula.
• In medium dark skies with GOOD seeing, I could almost, kind of, guessing, while moving the scope, see the darker area of the horsehead.
• Saturn was amazing!  The Cassini division was obvious and constant, just sitting there with direct vision.  Both inner and outer ring graded from bright to gone as you worked your way away from the division mark.
• An observer here commented "beautiful views" after looking at Saturn, then returned to his 20" binoviewer scope.  (As an aside, this 20" binoviewer scope knocked the socks off of anyone, including me, that looked at anything.  Those views definitely put me in my place!  Saturn was absolutely alive through that scope.)
• Star tests look very symmetrical around the center.  As I rack in/rack out, one side of focus is fuzzier than the other.  I notice this on ALL scopes that I look through, so wonder if it is my eyesight.  The other option is that I have a bit of a turned edge.  I will try it with a mask one of these days.