Random thoughts. I remember back when I started in this hobby (late sixties), American manufacturers listed eyepiece focal lengths in fractions of an inch. I had several, still have two that have the focal lengths engraved on the top as a fraction. When calculating magnification with these eyepieces, we always converted the eyepiece and objective focal lengths to millimeters first. So much cleaner than dividing fractions into whole numbers. In this country we still list objective diameter in inches, much of the time. Seems like any refractor under 4 inches aperture is sold as metric, most over that are in inches. Besides my astronomy interest, I credit my high-school chemistry classes for becoming fluent in both systems. Seems like chemistry was always metric. Even physics class back then was using terms like "foot-lbs." The Brits have been metric for a while, but I used to date a few who always gave their weight in terms of "stone". How archaic is *that*? All I can imagine is that it results in a much lower number than the same weight in kilograms. LOL! On Wed, Mar 27, 2013 at 6:32 PM, D P Pierce <starsbirdsglyphs@gmail.com>wrote: