6 inch binocular telescope

 

 

 

 

     

 

 

·         Lumicon helical focusers

·         Left hand focuser is fixed on circular base

·         Right hand focuser pivots on lower brass bolt for interocular adjustment

·         Uppermost brass nut tightens to hold right hand focuser at desired separation from left hand focuser

·         Small aluminum bracket holds Rigel Quickfinder

 

 

 

                  

 

 

·         View looking into tube from upper end

·         Focusers are seen in upper right of image

·         2 six inch primary mirrors are seen in lower end of tube

·         lower primary mirror is forward of upper primary mirror

·         upper, smaller secondary sends light from upper primary to upper focuser

·         lower, larger secondary sends light from lower primary to lower focuser

·         two control wheels are connected to dowels which permit adjustment of lower primary mirror—this to “follow” lower focuser as it is adjusted for interocular spacing

·         Curved vanes spread defraction aberration around bright objects, approaching an unobstructed view.

·         Tube is 12 inch thin wall PVC irrigation pipe

 

 

 

 

 

·         Rear view of tube

·         Holes are for cooling and could be larger – glass equilibrates in about 20 to 30 minutes and thereafter tracks temperature changes well

·         Upper primary is collimated with three brass knurled knobs

·         Lower, forward primary is mounted on a second bulkhead and is adjusted by rods and wheels in pix above

·         Bulkheads are ¾ inch fir plywood

 

 

 

This telescope employs 2 f/8 optical paths very similar to the 60 mm refractor detailed on this site.  One optical path is accurately collimated while the other is continually adjustable to accommodate varying interocular spacing.  This doubtful approach at f/8, interestingly, works very well, permitting use of magnification up to 250x which is a practical limit for this scope due to hand tracking and available light issues.  The scope easily accesses 11th magnitude galaxies, splits Epsilon Lyrae at 75x and will show 5 stars in the Trapezium in the Orion Nebula.  Lunar and planetary detail is stunning.  I made sketches of Mars the night of close opposition 8.27.2003 at 250x and could really see Solis Lacus.  Primary mirrors are from University Optics and secondaries are from Protostar.  Both have enhanced coatings. Several folks have shown interest in this design.  I saw a Herschel binocular at TSP about 15 years ago, built by Peter Wraight.  The eyepieces were in line with the long axis of the scope which had two tubes, one on top of the other, with the light path of the lower tube passing through the upper tube.  The tubes were slid back and forth longitudinally to adjust interocular separation.  This all worked well except after tilting the scope upwards about 45 degrees, rotation of the neck and upper body came to a tense halt.  The scope’s usefulness was limited and was very hard to view through near the zenith.  I thought about all this for a while and built the scope you see here.  It was suggested I patent the design-- something I’ve never considered regarding any of my limited “inventions” as an ATM, but bursting with pride for having stood on Herschel’s and Wraight’s shoulders and having thought up a viable solution to provide comfortable viewing through this type of scope, I checked existing patents and found James Carlisle designed a similar scope, built it, took it to Riverside, and then secured a patent on the light path, precluding my doing anything further with the design. 

 

     

            

             Comfortable viewing from zenith

                                        

                                                                                                                                                         

 

                             to horizon   

 

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