Is Magnification Consistent?

Abstract

Is the phenomenon of magnification by a converging lens inconsistent and therefore unreliable? Can a lens magnify one part of an object but not another? Physics teachers and even students familiar with basic optics1 would answer “no,” yet many answer “yes.” Numerous telescope users believe that magnification is not a reliable phenomenon in that it does not work for stars. This belief was central to the arguments of one of science's most prominent modern critics—a great story of how misunderstanding basic optics helped to yield bad ideas about science. So magnification is a great topic! It is accessible to students. It gives students insight into the workings of a familiar device such as a telescope that even frequent telescope users often lack. And it has a fascinating side story about how misunderstanding basic science led to interesting consequences.