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What is White?
We know what yellow is. Yellow light is
given off by car indicators and sodium
streetlights. It’s clustered around the
part of the spectrum that stimulates
the R(ed) and G(reen) sensors in the
backs of our eyes, while leaving our
B(lue) sensors unbothered. And a
yellow object, like a banana, refl ects
back any yellow light falling on it, while
absorbing the red, blue and purple.
Some say there’s no such colour
as ‘white’. Which is silly, as you can
also off ers the old-fashioned light
bulb (Incandescent, or sometimes
Tungsten), and one for Flash. And
for those of us who really can’t be
bothered, there’s the Auto White
Balance (AWB) setting.
Sunset
The sun’s going down, and there’s
a pinky glow across the snowfi elds.
‘What’s that nasty pinky glow?’
says Camera, and cunningly
go into Homebase and buy white paint
just like yellow or magnolia. A white
object, such as a snowfi eld, is simply
one which refl ects back all of the light
falling on it and doesn’t absorb any.
But then, what is ‘white’ light?
Using the same defi nition as for
yellow, we’d say that white light is ‘all
of the light that may be falling on an
object’. Which just says that white
light is light – not too helpful.
We could defi ne ‘white’ light as:
an equal amount of all the diff erent
coloured wavelengths. Trouble
adjusts AWB to get rid of it. But
that pinky glow was what we were
taking the pictures of! You can
use AWB in the evening – or you
can save the bother of deleting the
disappointing photos afterwards,
and just clear off down to the
nearest pub. Using AWB does the
job of recording colours worse
than our old, ignorant fi lm camera
would have done.
During the golden hour leading
is, there’s an infi nite number of
wavelengths, and no way to say what
makes up an ‘equal’ amount of each
of them. Weirdly, this meant that
there’s no such thing as white light.
What the human eyeball does
is pick out some objects it knows
are white ones: snowfi elds, clouds,
other people’s eyeballs. Then it takes
whatever light is falling on them as
being, for the time being, ‘white light’.
Unless it happens to be sunset or
something.
up to sunset, I fi nd Daylight gives
a fair rendering what I actually
saw. As the sky reddens, I switch to
Cloudy. For purplish post-sunset
dusk, even the Shade setting can
work. You could try switching
around among them.
And while you’re switching,
give old AWB a go. Just to confi rm
that all that work you put in
fi nding the WB button really was
worth it...
Daylight The colour of sun light changes over the course of a day, from red-orange when the sun
is close to the horizon to a spectrum with more blue in it when the sun’s high in the sky. (In winter,
perversely, the sunlight stays near-horizon ‘warm’ all day.) Daylight assumes that the sun is directly
overhead, when sunlight is closest to what it started off as: the natural radiation of a white-hot object
at 5500° Kelvin. (Ah, so that’s why my colour-balance slider is measured in degrees K!)
AWB Here a camera tries to do what our eyes and brains do so cleverly: assess a scene, work out
what the incoming lighting actually is, and adjust accordingly. It works most the time. In particular,
iPhones and the like have artifi cial intelligence that’s tremendously clever at working out what the
colours really would have been. iPhones sometimes go even further, adding pizazz and luridness to
suit Instagram tastes. So no more sitting about in a cave waiting for the magic pre-sunset light. iOS
applies that magic lighting anyway, saving you time, a damp bum and a nasty cold in the head.
Cloudy On a grey dreary overcast day, really interesting rock architecture can make a decent picture
anyway. Except, when you get the picture back home on the screen, it didn’t. There’s a kind of
dreariness fi lter spoiling your careful composition. This is actually a blue cast in the light, neutralised
out by your brain at the time and, to some extent, by the AWB in the camera. But Cloudy does a better
job. So, no more relaxing on the grey days and stuffi ng the camera in the sack. Switch WB to Cloudy
and get back to work!
Shade Inside Lord’s Rake gully, on a sunny day – this is lit not by sun but by the blue sky, and is even
more blue-spectrum than overcast light. To add some colour to the gloomy blueness, you either need
to dress your companions in orange or, use Shade, which will return much-needed warmth to the shot.
Incandescent Old fashioned light bulbs and candles give a yellow light. (Yes, it’s the natural
radiation of an incandescent object at 3500°K - viz, the little bit of wire in the light bulb.) Before
White Balance, indoor photos without fl ash had a homely golden glow. To retain that warm glow,
keep the camera on Daylight. To get rid of it, and capture what the adapted eye would actually have
perceived, switch to Incandescent. Shoot outdoors with Incandescent and you get revolting bluey
pictures that make you wish you’d never found out about white balance in the fi rst place.
Flash Light from fl ash is slightly bluer (‘cooler’) than natural, but with a somewhat diff erent mix of
wavelengths. (The colour can vary depending on the power setting selected, and also the age of the
fl ash.) OF’s editor sometimes uses Flash in the daytime, for a subtly ‘lukewarm’ colour palette.
spring 2019 | Outdoor focus 9