HISTORY

Optics acquired for the 10″ Prototype

While I was working on the Primary Mirror which I had intended to put into this Prototype this past winter, my work area got too cold and the pitch lap became too hard and brittle. This environment made polishing and figuring the mirror impossible. I didn’t want to stop building this prototyre so when I saw a used Meade DS-10 on ebay, I went ahead and did some research.

In the “SKY & TELESCOPE” ads from the 1980s, Meade claimed was the following…

10 inch F/4.5 Reflecting Telescope. With null-figured, diffraction-limited Pyrex parabolic primary mirror and matching (2.60” M.A.) 1/10 wave flat secondary”

I bought the DS-10 pictured above and used the optics to design the crateAscope

I assumed when I bought this DS-10 that the optical components were original to the scope, but the mirrors were not marked with any manufacturer’s name. Both the primary and secondary mirrors had aluminized coatings that were in very good condition.

I didn’t have the equipment necessary to test the flat secondary mirror, but I did test the primary mirror.  The Ronchi test revealed a good edge with a smooth and even parabolic surface.  The foucault test also revealed a good edge and a smooth surface. Figure XP software was used to calculate a P-V waveFront Error of 1/5 wave, a Surface RMS Error of 11nm, and a Strehl Ratio is 0.937 

I’m still not sure if this was the original primary that Meade supplied with this DS-10, but these are respectable numbers for a large fast primary mirror and are within Meade’s advertised specs.

CONSTRUCTION DETAILS FOR THE PROTOTYPE
  • The Body, Rocker Box, Bearings, and Enclosure were made from new Baltic Birch
  • It has a new High Point 8×50 right angle Finder Scope
  • The round Tube section, Primary Mirror, Primary Mirror Cell, Secondary Mirror, and Secondary Mirror Holder came from the used early 1980s Meade DS-10 pictured above
  • It has a used AstroSystems Inc. low profile 2″ Crawford Focuser with a 1.25″ Adapter
  • Also pictured is a used Meade 1.25″x25mm fl. Plossel Eyepiece giving a magnification of 45x and a 1.15 degree AFOV/actual field of view