Polarized opinions

Mike Harris adds punch to the sky and removes glare using NiSi's True Color NC circular polarizing filter

- Mike Harris

The polarizer isn't just a landscape photography essential: it's the multitool of filters. Its ability to block polarized light from a specific direction reduces glare from sunlight, and boosts both contrast and colour saturation. This results in the punchier skies most people associate with polarizers, but also the ability to cut through reflections in water. If that wasn't enough, a polarizing filter's light-blocking properties allow it to double as a handy one-or two-stop neutral-density filter. Polarizers are available to suit a variety of systems and budgets. We used NiSi's new V7 Holder with True Color NC CPL (£199/$199), which can also house three 100mm filters, in addition to the polarizer.

CPL stands for circular polarizer; although our NiSi filter is quite literally a circular object, the name actually derives from the way CPLs filter light, not their shape. As such, they're available as either screw-in filters or to fit square slot-in systems, which usually have a special recess built into the holder. Not all polarizers are circular polarizers, though. Linear polarizers also exist, but the way they filter light has been known to affect metering and autofocus systems, which is why CPLS are more commonly used.

Polarizing filters can be rotated to achieve varying levels of polarization. Rather cleverly, the NiSi True Color NC CPL clips onto the V7 Holder and is rotated via a pair of thumbwheels. This means the polarizer can be paired with slot-in filters, without having to rotate the entire attachment.