130521

130521 Telescope Workshop notes, May 21, 2013
JerryW,EdK,DmitriiZ,TomT
TimC had emailed earlier about his creation of a few documents this week for future handouts at Tinker Festival, July 21, coming up. https://www.sbnature.org/content/186/file/FLYER_tinker_WEB.jpg
DZ did not have his mirror this week, so we just did table talk.
EdK told us about his 100 mile weekly bicycle trips, using an 18 pound carbon fiber bike. He mentioned how Schmidt Cassegrain scopes have the corrector lens made by pulling a vacuum.
https://en.wikipedia.org/wiki/Schmidt_corrector_plate
JerryW was asked about his current grinding status: he is working on his 18" moving to 120 grit from 80 grit. The grinding process for his simultaneous three mirrors will take all summer to finish, before moving to polishing stage. Cleaning larger grit from his tiles before moving to finer grit requires hours of scrubbing his tiles with a toothbrush.
JerryW talked about putting mirror on top of tool to prevent flattening of mirror, which happens when tool is used on top of mirror glass. Time to grind 18" vs smaller mirror is the same if tool is same size as mirror.
JerryW was asked about types of eyepieces: Plossel vs Nagler vs. Televue Ethos.
-Naglers are heavy due to multiple lenses
-Televue Ethos made by Nagler for wider field of vision?
-Plossels are OK, but be suspicious of unknown brands.
https://en.wikipedia.org/wiki/Eyepiece