1 The Director of Photography – an overview

126 Practical Cinematography
Figure 14.6 The colour
temperature of sunlight at
different times of day
Direct sunlight Shadow Deep shadow
i.e. meter turned away
from the sun
8.30 a.m.
4500°K 5300°K 6400°K
Noon
5350°K 4550°K 5450°K
direct sunlight and the shadowed readings are almost transposed in
the three and a half hours from morning to noon.
Correcting lamps
Correcting may not be an entirely accurate word in this context. We
use it when we want to convert a tungsten lamp to daylight or a daylight
lamp to tungsten. You can, of course, make partial conversions,
as we shall see.
To convert a tungsten lamp to daylight you must put a full colour
temperature blue (CTB) filter in front of the lamp.You will lose a considerable
amount of brightness as, in effect, the lamp has become much
less efficient.To convert a daylight lamp (say an HMI) to tungsten you
must put a full colour temperature orange (CTO) filter in front of the
lamp.Again, you will lose a considerable amount of brightness, though
not quite as much as in the previous example.
To convert a daylight scene for tungsten-balanced film you put a
Wratten 85 filter on the camera.
Of course, you can make partial conversions for the sake of art. For
instance, if you were to film an interior that had a practical window
in the shot with a daylight scene outside it and you wished the window
to be just a little colder than the interior, thus heightening the feeling
of separation between the interior and the exterior, then you might
decide to achieve this as follows:
1 The exterior you can do little about without going to considerable
trouble, so leave it as daylight, say 5600°K.
2 Light the interior with light corrected to half daylight, say 4200°K.
You achieve this by using tungsten lamps with half blue filter (half
CTB) or daylight lamps with half orange filter (half CTO). Which
you choose matters little, it just depends which is more convenient.
3 You now have an exterior that appears colder than the interior. If
you correct the camera to the interior you have achieved the
objective. You do this by using tungsten-balanced film and putting
on the lens a filter equivalent to a half CTO. This filter is the
Wratten 85C (Mired shift value ��81).
Now camera and interior are in harmony and the exterior appears a
little cool. This can be a very pleasing effect.
It has become part of the mythology of filming that, in the above
example, you should use a Wratten 81EF camera filter. Please do not
do this.The 81EF was designed specifically for professional Ectachrome
film. It is nowhere near a half 85 and produces some very unpleasant