BTW, if anyone is interested, here are my other two "Woodshop" articles in the series S&T published: Feb. 2000 page 125 Telescope Techniques "Woodshop Eyepieces" March 1999 page 120 Telescope Techniques "Woodshop Telescopes" Here are some essays by Roland Christen, on the subject of refractors. Some good information: http://geogdata.csun.edu/~voltaire/roland/color.html http://geogdata.csun.edu/~voltaire/roland/ed.html http://geogdata.csun.edu/~voltaire/roland/musing.html I would also like to note that people should not sell the achromatic doublet short. I have seen amazing lunar and planetary detail in Ziggy's refractor and Andy at SPOC. Andy is also an amazing deep-sky scope, outperforming 8" SCT's, in this user's opinion. The lack of a central obstruction can make up for incomplete color correction, apparently. Also the corrector plate on SCT's does introduce a mild amount of chromatic abberation.