1 The Director of Photography – an overview

The laboratory 85
Figure 8.3 The optical printer
5%
10%
Shadows
5%
50%
Mid-tones
5%
90%
Highlights
Figure 8.4 The effect of flare in
an optical printer
Master Negative
Raw Positive stock
Shutter
Linked Intermittent
Mechanisms
Light Source
Condenser Lens
Objective Lens
Negative Film Gate
Positive Film Gate
through these gates one frame at a time by linked intermittent mechanisms.
In order to transfer the image from the negative to the positive
film, an objective lens is positioned between the two gates.
The purpose of this layout is to enable optical effects, such as fades
and dissolves, to be achieved. A dissolve is made by first printing
the outgoing shot and fading out the printer light. The positive film is
then rewound and the incoming shot replaces the outgoing shot. The
printer is then restarted and the light source faded in over the same
section of print stock. This produces a situation where the outgoing
image is reduced in exposure at exactly the place on the positive where
the incoming exposure is increasing. Therefore, the overall exposure
from the two negatives always adds up to the full, correct, exposure.
Although an optical printer can achieve many elegant effects, it
does have two distinct disadvantages. Firstly, because it has, by its very
needs and design, an intermittent mechanism, it cannot be run at anything
like the speed of the contact printer.Therefore, optical prints will
always cost considerably more than contact prints because of the extra
machine time. Secondly, although the objective lenses used in optical
printers are always of the very highest quality, often being specially
computed for the task, nevertheless no optical path, even if it only
contained air, will ever produce a print as perfect as one made with the
two emulsions in absolute contact.
The cinematographer must be aware that there will be two slight differences
in the appearance of a contact print and an optical print. Due
to the optical path travelled by the image between the two emulsions in
an optical printer, there must be a slight loss of definition compared
with a contact print. This is hardly worth worrying about, as the loss is
very, very slight. The second important effect of the optical printer is to
introduce a little flare, again as a result of there being an objective lens
between the two emulsions. Flare is simply a very small amount of the
total amount of light forming the image being lost to the image and
redistributed, evenly, over the whole of the image.The effect of this is to
add a small percentage of the overall image to all the tones in the image.
In Figure 8.4, the effect of flare has been greatly exaggerated in order to