1 The Director of Photography – an overview

138 Practical Cinematography
inch and divide it by two and a half, we come to approximately one twothousandth
of an inch. Therefore, if the one two-thousandth of an inch
circle of confusion on the 16 mm negative is blown up to 35 mm it will
now be approximately one seven-hundredth of an inch across. In these
circumstances, if the Super 16 original was shot using depth of field calculators
computed at a circle of confusion of one two-thousandth of an
inch, the 35 mm print should look just as sharp as if it had been originally
shot on 35 mm negative.There are, of course, several other factors
at play in this kind of blow-up, but at least the circle of confusion on the
print will remain correct for 35 mm theatrical presentation.
Super 16 mm and 16 � 9 television
A depth of field calculator based on a circle of confusion of one
thousandth of an inch has been universally used in television for shooting
standard 16 mm. This works very well and produces images appreciably
sharper than any television system can handle. The coming of
widescreen television has added width to the television picture, with the
screen height remaining the same. Nearly all film for television, at least
in the UK, is now shot using Super 16, and as Super 16 has very nearly
the same aspect ratio as the new 16 � 9 televisions, this negative produces
almost exactly the same definition as the old standard 16 mm negative
did when shown on a television with the old aspect ratio of 4 � 3.
Widescreen or 16 � 9 televisions are sold, particularly if they are
capable of receiving digital transmissions, as having better definition.
This is not wholly true. There are still only 625 lines being transmitted
vertically, so there is no possible increase in definition there.The width
is greater and to maintain the horizontal definition more horizontal
bits of information are transmitted, but still only roughly the same
number of bits per inch of screen width. As far as recording the image
on film is concerned, the definition requirements for a standard 16 mm
original shown on a 4 � 3 television and those for a Super 16 original
shown on a 16 � 9 television are therefore virtually identical.
The greater apparent definition on the screen comes from less interference
between the transmitting station and the receiver, and is
therefore not affected by the camera origination.
Depth of field of 35 mm film when only shown on
television
It is not uncommon to be asked to shoot 35 mm commercials that are
only ever going to be shown on television. In these circumstances, the
definition of the 35 mm film is so superior to any television system that
the allowable circle of confusion may safely be reduced to one fivehundredth
of an inch.
Choosing the circle of confusion to use on set
Where does this leave the focus puller and their calculations? If they are
certain that the Super 16 original is never going to be blown up to 35 mm,
then they would be well advised to use a depth of field calculator based