Freediving
Also known as: breath-hold diving, apnea
Diving on a single breath, filmed in a medium that removes colour, light and sound, and where the camera operator is also holding their breath.
Updated
What it means
Freediving has no equipment to hide behind. A diver descends on one breath, which means every second of a session is limited by physiology rather than by an air supply or a battery.
Water changes the image at every depth. Red disappears within a few metres, contrast falls away, and by twenty metres down everything reads as blue regardless of what colour it actually was.
Sound disappears entirely. There is no audio worth recording at all, so the whole soundtrack has to be built afterwards, which makes the result closer to a Travel montage than to an action edit.
How it works in practice
A filter restores what the water removed. A Red filter at depth brings back some of the colour that absorption took away, and it is the single most effective thing available for this.
Lighting is the alternative below a certain depth. An Underwater video light puts real colour back rather than correcting what is left, and beyond about fifteen metres it is the only option.
Safety governs the camera position. A safety diver is watching the diver rather than the shot, and anybody filming is a third person rather than one of those two.
What to watch out for
Grading cannot invent red. A clip shot without a filter at depth is missing the information entirely, and pushing colour afterwards produces noise rather than any recovery.
Housings fog from the temperature change. Warm air sealed in at the surface condenses as the housing descends, which is Housing fog and ruins every clip taken after it starts.
The depth rating is a limit rather than a target. A Depth rating is tested in still conditions, and a housing taken near its limit in moving water is being gambled with rather than used.
How RawClip handles it
Underwater clips are graded for the colour shift during assembly, which handles the ordinary blue cast. Footage shot at depth with no filter or light is missing information no grading step recovers, so the filter fitted at capture does more for the result than anything afterwards can.