Polarizer filter
Also known as: polariser, CPL filter
A filter that blocks light vibrating in one plane, which cuts reflections off water and glass and deepens an otherwise pale sky.
Updated
What it means
A polarizer removes polarised light, which is most of what a reflection consists of. Rotating it changes how much is blocked, so the effect is adjusted by turning the filter rather than through any Pro mode setting.
The visible results are specific rather than general. Reflections off water and glass weaken, a washed out sky deepens, and wet surfaces stop glaring, which is why it is the one filter surf and water footage genuinely needs.
It is not an exposure tool. A ND filter exists to reduce light so a slower shutter is possible, while a polarizer changes what the light is rather than how much of it arrives.
How it works in practice
Rotation is the whole control. The effect peaks at roughly ninety degrees to the sun and disappears when pointed at or away from it, so the angle has to be set for the shot rather than once.
It works best on water looking down into it. Shooting a wave or a pool from above with the filter rotated correctly reveals what is under the surface instead of the sky bouncing off it.
Accepting the light it takes away is part of using one. A polarizer absorbs a stop or two, so Exposure has to be reconsidered rather than assumed unchanged.
What to watch out for
A fixed mount makes it awkward, because the correct rotation depends on direction and a camera strapped to a bike changes direction constantly through a run.
On an ultra wide lens the effect is uneven across the frame. A sky can be deep on one side and pale on the other, which looks like a fault rather than a filter.
It also cannot be undone afterwards. Unlike a grade, a reflection that was blocked is simply absent, so the decision is as permanent as Fisheye correction applied in camera and should be made with that in mind.
How RawClip handles it
Footage is scored on what is visible in it rather than on how it was filmed, so a clip where a polarizer revealed the water under a wave simply has more to see and scores accordingly. Nothing is simulated afterwards.