131105

131105 Telescope Workshop notes 730-9p Tuesday evening
Attendees:  EdK, TomT, TomW, JerryW, JoeD, ChrisU, Megan & Mike R., TimC









 JerryW started talking optics and telescope history with Megan & Mike.  Getting rid of coma in telescopes has been a big deal over the centuries. http://telescopesinhistory.com/

EdK brought in his 12.5” and newly pitched tool, he worked 3hrs of polishing at home in the past week, so TomW will setup the Ronchi test.  Inside R was showing a much smoother surface than two weeks ago but with a turned down edge and flat center which JerryW says can be corrected with a chordal stroke around the edges without the center of the tool going over the edge!  Another take here about oblate surface and turned down edges: http://www.loptics.com/ATM/mirror_making/oblate/oblate.html

ChrisU brought in the telescope mirror tube and bearing box of his Flaming Tomato Dobsonian to which he has added a V pattern with white tape.  He was looking to slip his mount onto his tube, but will do this at his studio instead due to the need for tools and time to work with the nyloc nuts of the mirror cell.  [Don't forget to check out his art exhibit at the Museum of Contemporary Art, Paseo Nuevo, upper level:  http://www.mcasantabarbara.org/sites/default/files/exhibitions/press/cfe_snell_reduced.pdf]

TimC brought in the 8” donated mirror for more grinding with 220grit.  He showed Megan & Mike how the colors are focused with a parabola, and he showed his grinding method and the mirror surface with the magnifying loupe.

Jerry suggests getting the SBAU telescope workshop onto astronomy club links area of Stellafane site.  Done!  see: http://stellafane.org/tm/mc/other.html
More photos/vids of tonight: http://www.flickr.com/photos/27241501@N03/sets/72157637401584815/