NiSi Polariser
A circular polariser is, in our opinion, the absolute #1 must-have creative filter. It saturates colours, enhances contrast, removes glare and reflections and is absolutely indespensable for all photographers and filmmakers. For more information on what a circular polariser is and how to use it, read this article by Hougaard Malan.
What is the difference between a linear and circular polariser? Digital cameras' AF systems are not compatible with linear polarizers. When the world was transitioning from film to digital, linear vs. circular was a big debate, but it no longer is. For photographic purposes, you can assume that any polariser on the market nowadays is circular and not linear.