1 The Director of Photography – an overview

Lighting ratios 109
Figure 11.3 The range of
lighting ratios that can be
shown on different systems
Tape Transfer Image Brightness
Brightness Ratio 32:1
Cinema Release Print
Television Low Key Scene
Television “Normal” Scene
Television High Key Scene
Print Density – Image brightness Ratio 128:1
Lighting ratios when shooting for both cinema
and television
The way films are funded these days, with often a significant amount of
the production’s capitalization coming up front from television rights
and video sell-throughs, it is important that the cinematographer
knows when shooting a scene exactly how it will look when delivered
on the two, quite different, media. The key to this is the lighting ratio.
The first thing to realize is that the tonal range of the television version
is going to have to come from within the tonal range of the cinema
version.This is mainly because the television version will be, most
often, telecined from the cinema print. This, in these circumstances, is
not necessarily a disadvantage. You have probably put considerable
effort into grading the cinema copy and, therefore, much of your grading
for television, say the overall brightness and colour, will have
already been achieved.
At the telecine grading of your cinema print you must remember
that you don’t have to take your 32:1 television version from the middle
of the 128:1 cinema version. For an absolutely normal daylight
scene this may well be appropriate, but for a high-key or low-key scene
or a night exterior scene or snowscape it would be inappropriate.
Figure 11.3 shows the sensitometric curve for a typical cinema release
print.The straight-line section has a box overlaid on it, representing the
seven-stop exposure range that would result in a first-class image on the
cinema screen. Inside this box is another, showing the centre section
that would be used to make a normal transfer from this print to a videotape.
As is clear, the equivalent of one stop of information in the highlights
together with another stop of information in the shadows will not
be transferred and will be totally lost to the television audience.
By comparing the 128:1 tonal range of the release print shown at the
bottom of the print with the 32:1 tonal range of the video transfer
shown at the side of Figure 11.3, you can see a very graphic demonstration
of how the range is dramatically reduced.
Just below the curve is a box showing how one might transfer a lowkey,
or night, scene to tape. In this kind of scene it is the shadows that
contain most of the information the cinematographer wishes to show