Updated Sept. 25, 2021
If you have bought an old 35mm kit at some point (or five...or fifteen...you'll get no judgment from me ;-)), you have likely encountered a polarizing filter in among the customary packet(s) of lens tissues, bottle(s) of cleaning fluid (either unopened or completely evaporated), a blower brush that develops negative thrust, crummy 2x converter (usually described as a lens ;-)), and a gaggle of other accessories to the crime. Of all that seeming detritus, the polarizer could prove to be the most useful to you in your photographic journey. But like any tool, it can be misused, overused, and in some cases even prove detrimental to your camera's metering or focusing performance, and image quality. So how do polarizers work? How can you maximize their performance? And which type of polarizing filter will be right for you?
Suffers from a quarter-century and counting film and manual focus SLR addiction. Has recently expanded into 1980's AF point and shoots, and (gack!) '90s SLRs. He even mixes in some digital. Definitely a sick man.