The amateur telescope making pursuit began with the simple aim of making telescopes, hut in next to no time the nimble-minded people to whom it appealed were running all over the field of precision optics in starch of other instruments they could build, while some delved into physical optics to understand its theory, and all to some extent did both. The old demarcation between amateur and professional optics receded, became blurred, or vanished. Neither can that demarcation be found in the present volume, which is for all who are interested in optics, though essentially for amateurs. Some of its authors are amateurs, some are professionals who began as amateurs and have remained so in their spirit of enthusiasm, and a few are professionals who never were amateurs but nevertheless have fun with optics.