Polarizing filter (CPL)
Also known as: CPL, circular polarizer, polarizer
A rotating filter that cuts reflections from water and glass and deepens blue skies. Popular on drones and for water sports, it also darkens the image.
Updated
What it means
Light reflected from water, wet rocks, leaves and glass becomes partly polarized, meaning it vibrates mostly in one direction. A polarizing filter blocks light polarized in a chosen direction, which removes much of that glare. Rotating the filter changes the effect, so it is usually called a circular polarizer, or CPL.
The results are distinctive: water turns transparent so you can see the riverbed or reef below, skies become deeper blue, and foliage looks richer because the shine on leaves disappears. These are effects no editing software can fully recreate afterwards.
A CPL also reduces the overall light by roughly one to two stops, so it acts as a mild ND filter too.
How it works in practice
Drones are the most common home for CPL filters, especially for coastal, lake and river shots where glare would otherwise hide the water. Kits often combine ND and polarizing effects in one filter for bright conditions.
The effect is strongest when the sun is at about 90 degrees to the camera direction and weakest when shooting toward or away from the sun. Set the rotation before takeoff, pointing the camera where you plan to fly, and check the preview.
For action cameras, CPL filters exist as screw-on or clip-on covers, useful for surf, kayak and boat footage where reflections on the water dominate the frame.
What to watch out for
On ultra-wide lenses, a polarizer can darken the sky unevenly, creating a dark band across one part of the frame. This is very visible on action cameras and wide drone shots. Reduce the effect by rotating the filter or skip it for very wide scenes.
Panning or orbiting changes the angle to the sun, so the strength of the effect shifts during the shot. On drones, an orbit can show the sky changing color as you circle.
The extra light loss matters in dim conditions, raising ISO and noise. Remove it at dusk and indoors.
How RawClip handles it
RawClip uses your footage as recorded and cannot add or remove polarization. Clear water and rich skies captured in the camera carry straight into your highlight, which the AI builds from your best moments.