Astronomy educator/Sidewalk astronomer
Owner of Astronomy Delight franchise
18 inch f4.42 Dob on eq platform w ST120 f/5 finder
12 inch Zhumell Dob
8 inch f/6.9 home made Dob with Seevers optics
William Optics red 10th Anniversary 80mm FD
C8 XLT on Vixen GPDX
26lb eyepiece box
Cernan Space Center astronomer
Member of Northwest Suburban Astronomers
Joined June 2012: Location, Ottawa, Ontario
Mes télescopes et jumelles:
150mm F5 Newt on EQ5, 127mm Mak Cass on AZ4
Oberwerk BT70-45 and 15X70 SkyMasters
Whenever I have come into large sums of money in my life, I always put half of it aside to spend on fast cars and the pursuit of loose women.
I put aside the other half to spend frivolously.
Quote:Even the "spherical" spot maks, such as those made and promoted by Gregory, involved a final phase of figuring with an autocollimator. Maksotov's original papers from the 40's also promoted autocollimation. When a surface is being mushed around and "retouched" to create a collimator null - it is effectively adding an arbitrary asphere, although small, to correct for any residual aberration in the system. So even a "spherical" mak has an asphere if the final figuring happens in an autocollimator.