Red filter
Also known as: dive filter, underwater color filter, magenta filter
A red or magenta lens filter for underwater filming that restores the warm tones water absorbs, so blue-green footage looks closer to natural color.
Updated
What it means
Water absorbs light unevenly. Red fades first, noticeably within the top few meters, followed by orange and yellow, so footage from depth turns blue or green and skin, coral and fish lose their warmth. A red filter over the lens holds back some of the blue and green, which pushes the balance back toward natural tones.
Red filters are designed for clear, blue tropical water. In greener lakes and temperate seas, a magenta filter does the same job better. Both are passive tools: they add no light, they only rebalance what reaches the sensor, so they work together with sensible white balance settings rather than replacing them.
How it works in practice
On action cameras, the filter clips onto the front of the dive housing or snaps over the lens cover. It works best in good daylight from a few meters down to roughly 15 meters, depending on water clarity. Deeper than that, there is too little red left to recover and a video light becomes the better tool.
Many divers keep a flip-up filter raised near the surface and drop it on descent. Film a few seconds of a white slate or your palm at depth as a color reference. A filter also swallows light, so the camera raises ISO and darker scenes get noisier; keep the sun behind you where you can.
What to watch out for
Using a red filter in shallow water or close to the surface turns everything pink, and that cast is hard to remove later. Take it off for snorkeling, shallow reef sections and shots aimed up toward the sun.
A filter also does not finish the job. It reduces how much color correction you need but rarely removes the need entirely, and if you switch on a video light while it is in place, everything the light hits turns oddly red. Pick one approach per dive: filter for ambient light, or lights without the filter. Cheap filters can be soft or scratch easily, which softens every frame of the dive.
How RawClip handles it
RawClip does not correct underwater colors, so the color you capture at depth is the color in your highlight. Getting it right in the water with a red or magenta filter really matters. Upload the dive clips as they come off the camera, and the AI handles choosing and cutting the action.