Underwater Photography Calculator

Camera housing depth rating and strobe positioning.

Depth (m)

Strobe GN (air)

Aperture (f/)

Water visibility (m)

Subject distance (m)

Water type (0=clear, 1=temp, 2=murky)

Tab to move between fields

Ambient light loss (stops)

1.4

Max flash range (m)

1.9

Red light loss (stops)6.7

Orange light loss (stops)3.3

Strobe GN (underwater)10.7

Flash power needed (%)62

Apparent distance (m)1.13

Backscatter risk (1-3)2

Yellow Loss Stops1.25

Flash AdequateYes

Recommended Max Distance M3

How to Use This Calculator

Enter your diving depth in feet and water clarity (visibility) in feet.
Select the water type (tropical saltwater, temperate, freshwater).
Set your strobe or video light guide number and target subject distance.
Review the Color Correction Filter recommended for the depth and water type.
Use the Strobe Power Setting output to get accurate exposure without backscatter.

How the result changes with Depth (m)

Depth (m): Diving depth in meters.
Strobe GN (air): Strobe guide number rated in air.
Aperture (f/): Camera aperture f-number.
Water visibility (m): Underwater visibility in meters.
Subject distance (m): Distance from camera to subject in meters.
Water type (0=clear, 1=temp, 2=murky): 0 = clear tropical, 1 = temperate, 2 = murky/green.

Ambient light loss (stops): Stops of ambient light lost at this depth.
Red light loss (stops): Stops of red wavelength absorption (gone by ~5m).
Orange light loss (stops): Stops of orange wavelength absorption.
Strobe GN (underwater): Effective strobe guide number underwater (~1/3 of air).
Max flash range (m): Maximum effective strobe distance at set aperture.
Flash power needed (%): Strobe power needed for correct exposure.
Apparent distance (m): How far the subject appears (refraction makes closer by 25%).
Backscatter risk (1-3): Backscatter risk score: 1=low, 2=medium, 3=high.

Identify Input Parameters
4 parameters
Depth (m) = 10, Strobe GN (air) = 32, Aperture (f/) = 5.6, Water visibility (m) = 15 = 6 input(s) provided
Calculate Ambient light loss
Ambient light loss = depthM / 10 + attenuationCoeff * depthM
1.4 = 1.4
Calculate Max flash range
Max flash range = flashGnWater / aperture
1.9 = 1.9
Calculate Red light loss
Red light loss = depthM / 1.5
6.7 = 6.7
Calculate Orange light loss
Orange light loss = depthM / 3
3.3 = 3.3