1 The Director of Photography – an overview

Camera filters 133
They are only fully effective when rotated for best effect – if the
subject moves, say our car, then the effect will change as the relationship
of the planes of the car change relative to both the direction of
the lighting and the camera. This is also true if you pan across a blue
sky – its blueness will alter depending on its relative angle to the Sun.
Polar filters reduce the exposure by one and a half to two stops. It is
often best to take a reading through the polarizing filter with your
exposure meter, but remember to have the filter at the same angle in
front of the meter as you will place it on the camera, since the rotation
of the polar filter will alter its absorption.
Filter factors
Filter factors are referred to as a simple whole number where a filter
factor of 2 equals a correction of one stop of aperture. Likewise, a factor
of 3 equals one and a half stops’ correction and 4 equals two stops.
If in any doubt, measure the filter through your meter but remember
to point it at the same colour light under which you will be photographing
the scene.
The pan glass or viewing glass
This is not strictly a camera filter but the piece of glass, in a holder,
often worn around the DP’s neck.These days it is not a pan glass at all,
but its origins are so strong that the name is now synonymous with
that little viewing filter and the name seems impossible to kill off. It
must be said that this filter is often worn, yes by me included, as a kind
of chain of office so that everyone on the set will know who is the DP.
In the days when all films were made in black and white, it was quite
hard to visualize the scene before the camera, which was of course
in colour, as it might be seen on a cinema screen in black and white.
Early black and white film was orthochromatic (ortho � singular,
chromatic � colour), meaning it was incapable of recording black and
white densities as a true representation of the colour brightness. In fact,
the film was sensitive mainly to blue light, which then required very
peculiar make-up, ladies’ faces being painted yellow and their lips black.
Black and white film stocks developed into what became known as
panchromatic emulsions (pan � many). These emulsions were much
more true in their rendition of colour brightness, as they could record
some red and green.
Cinematographers who were used to orthochromatic film emulsions
had considerable difficulty in imagining the tones that would be
recorded on the new emulsions.The solution was to produce a viewing
filter that the DP could look through that would, to the eye, give a fair
representation of the scene as it would be recorded on the new
panchromatic film. Hence the new viewing filter became known as a
panchromatic viewing filter – or a pan glass.
As black and white technology progressed, various viewing filters
were developed and matching pairs were sometimes available for working
under daylight and tungsten light.
Nowadays, the viewing filters should strictly be called colour viewing
filters, for they all try and show you the scene, not as black and white,