White Balance Settings

A'WB

Auto: Also known as AWB is perhaps the most popular setting as it uses thousands of algorithms programmed into your camera to best work out the white balance for your particular photograph wherever you may be. Auto setting as been developed over the years.

Since the third edition of this book was published, and for underwater use, I use 'Auto WB' 70% of the time — for the other 30% I use Preset White Balance.

Daylight: Has a symbol of the sun and is close to the colour temperature of traditional film;many of you will remember the 'Daylight' stamp on a box of film. Daylight has a colour temperature between 5000°—5600°K and is ideal for natural light and clear skies (on land not underwater).

Cloudy: Has a symbol of a cloud and a colour temperature of between 6000°—6500°K. It has the effect of warming up the colours.

Shade: Has a symbol of a house in shade;it is an increase of Cloudy WB setting. It has a similar warm-up effect but more accentuated than Cloudy.

Tungsten: Has a symbol of a light bulb denoting use indoors under domestic lighting conditions.

Fluorescent: Has a symbol of a fluorescent light and can result in a yellow or green cast. Try it indoors under fluorescent lighting but do remember to change it back to Auto when you have finished shooting.

Flash: Has a symbol of a bolt of lightning and the results are very similar to the Daylight setting.

A White Balance setting which I have yet to discuss is the preset function. Underwater, we have the most intense and predictable colour cast of all. You guessed it, the colour blue! As sunbeams pass through the surface, underwater colours are absorbed at different depths. Warm colours of red and orange are first to vanish and by the time we get to 25 metres the light spectrum is strongly biased towards blue.

White Balance Preset: PRE has the symbol of 'Pre' or 'Kelvin'.

FIG. 1.20 Preset function in camera menu.

With greater accuracy, you can control colour and limit the negative effect of the blue cast by using this function.

Locating the custom preset white balance function varies from one digital camera to another so check your camera manual for specifics. The general idea is to point the camera lens at something white or grey such as a piece of white card or perspex. The camera takes a reading from this object and adjusts the white balance to the colour temperature at this depth. Take a few test shots after the custom white balance is set and check the colour cast of the thumbnail in your LCD to see how closely it resembles what your eyes see.

To record a 'preset' measurement, the exposure has to be correct to within one EV (one f stop) for the viewfinder to indicate the word 'Good', or 'Gd', which confirms that the 'preset' has recorded successfully.

I have found all the following techniques to be effective in recording a 'preset' measurement:

• A grey or white coloured scuba tank used by another diver.

• Grey or white coloured fins providing they fill about 70% of the lens.

• Neutral (grey or white) coloured sand, rocks or corals.

• White or grey card available from popular photographic outlets.

• When shooting a scene using 'preset' white balance you must turn your flashguns off or else a red/pink colour cast will occur from the colour temperature emitted by the flash. It's not sufficient to point the flashgun in an opposite direction as it may still colour the water with a red cast. I emphasise that you should turn the flashgun to OFF!

Tips

I tend not to bother with a white or grey card to set a preset white balance underwater. I have found that using the palm of my hand to fill the viewfinder works just as well.

With certain makes of camera the procedure of setting 'Pre' does not record a photograph on the sensor, just the measurement, which is stored within the 'preset' menu on your SLR.

FIG. 1.21 Natural light image taken with Tokina 10 mm—17 mm lens at the 17 mm end, f11 at 1/125th sec. My WB was set to Auto. I composed this Red Sea reef-scape from a downward angle with the sun behind my back.

FIG. 1.22 Using the WB colour picker (see Fig 1.23) in Lightroom 2 or Photoshop Elements/CS, I moused down to the white reflective stone in bottom left-hand corner of the photo and clicked to restore the colour as in this figure. See how the effect of the blue filtration has been reduced and restored the scene similar to how it looked to the eye.

FIG. 1.21 Natural light image taken with Tokina 10 mm—17 mm lens at the 17 mm end, f11 at 1/125th sec. My WB was set to Auto. I composed this Red Sea reef-scape from a downward angle with the sun behind my back.

When I shoot natural light, I always shoot RAW and take a 'preset' reading off the palm of my hand or the subject itself, if it happens to be close enough. I have learnt from my mistakes that it is best to take a 'preset' at a similar depth to the subject. If I ascend or descend more than 1.5 m I will remeter the WB 'preset'.

FIG. 1.22 Using the WB colour picker (see Fig 1.23) in Lightroom 2 or Photoshop Elements/CS, I moused down to the white reflective stone in bottom left-hand corner of the photo and clicked to restore the colour as in this figure. See how the effect of the blue filtration has been reduced and restored the scene similar to how it looked to the eye.

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