Bolex Paillard C8 Manuel D'Instructions
Exposure meters
Photoelectric exposure meters help the movie-maker to determine the
diaphragm stop which should be used under various lighting conditions.
They are suitable for both black-and-white and colour films. Depending on
the model, they measure either incident or reflected light. Exposure
meters, which are highly delicate instruments, are usually carried as a
separate unit for utmost convenience in use.
diaphragm stop which should be used under various lighting conditions.
They are suitable for both black-and-white and colour films. Depending on
the model, they measure either incident or reflected light. Exposure
meters, which are highly delicate instruments, are usually carried as a
separate unit for utmost convenience in use.
Setting the diaphragm
The amount of light which, after passing through the lens, reaches the film,
is limited by the aperture of the diaphragm. The smallest number on the
scale corresponds to the widest setting of the diaphragm.
is limited by the aperture of the diaphragm. The smallest number on the
scale corresponds to the widest setting of the diaphragm.
The graduations on the diaphragm scale are known as ‘stops‘. When the
diaphragm is closed by one stop (e. g. by altering the setting from f : 5.6 to
f 8), the amount of light reaching the film is halved. Conversely, opening
the diaphragm by one stop (e. g. from f : 8 to f : 5,6) doubles the amount of
light admitted. Opening the by two stops quadruples it, and so on.
diaphragm is closed by one stop (e. g. by altering the setting from f : 5.6 to
f 8), the amount of light reaching the film is halved. Conversely, opening
the diaphragm by one stop (e. g. from f : 8 to f : 5,6) doubles the amount of
light admitted. Opening the by two stops quadruples it, and so on.
In determining the correct stop to use, three main factors must be taken
into account :
into account :
the intensity of the lighting
the speed of the film
the filming rate.
the speed of the film
the filming rate.
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