underwater videographer course | underwater video technique | exposure

Exposure

How to control the exposure of video cameras underwater

Think of exposure as the amount of light reaching the sensor

Iris

Equivalent of "aperture" in stills photography

Depth of Field - http://www.dofmaster.com/dofjs.html

Avoid very small iris - quote from Z1 manual

Shutter Speed

Camera normally defaults

This gives smooth video and lets the maximum light in

Slower shutter speed than this gives a strange "strobe" effect. Try it.

Faster is OK but very fast speed can give "steppy" effect

Fast shutter is good for shooting specifically for slow motion because NLE fills in frames based on interpolation, and this is easier with less motion blur (Drew). If you want ¼ speed motion in delivery, then go for 4x shutter speed.

Also for extracting stills of moving subjects

Gain

Too much gain = noise

Equivalent of grain in fast film

Some say 0dB always but deep you need some gain

Auto exposure versus manual exposure

Pumping

Don't be afraid of blacks (example clip panning across wreck windows)

Subject can be too light or too dark on auto

Task loading too much in some circumstances

Manual for night dives

Manual for macro when have time

Show exposure info during playback/capture

Then switch iris to manual and adjust. Often down a couple of notches but sometimes brighter. If iris gets very small then increase shutter speed or flip in an ND filter. I use 100, 150 and 300 a lot

Zebras

70 for skin tone

100+ for underwater

100+ shows areas totally white, no detail

It's OK to have some zebras for some shots, otherwise dark areas too dark. But avoid large areas of 100+

Lock down gain to 0dB, shutter to 1/50 and put iris on auto to see what you've got

Neutral Density Filters

Neutral density filters versus faster shutter speed

CC filter acts as a filter, cutting out X stops of light

Amphibico cannot access ND filters

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