Page 7 - RD_2025-09

A number of home movie equipment manufacturers have produced
combination camera-projectors over the years – in most cases the compromises required
to combine the functions of the two units resulted in neither unit providing performance
approaching that of a purpose-designed individual unit. Cameras and projectors have
some basic functions which at first look could perhaps be combined into a single unit
and which may offer some cost saving and convenience.

Before looking at a number of examples that have been produced over the years, a look
at the basic requirements of a camera and a projector may be useful.

THE CAMERA A cine camera has certain basic requirements, which can be stated as:

● A film transport mechanism, which is capable of moving the film fame by frame,
holding it steady in the gate while the shutter is open, and advancing the film to the next
frame while the shutter is closed.
● A lens, capable of focusing the image of the subject onto the film, with a method of
adjusting the amount of light passing through it to the film
● A shutter, which will pass the maximum amount of light during its open phase and
pass no light during its closed phase; the open phase to be a long as possible to allow
maximum light transmission and therefore best low light performance.
● A viewfinder, to provide a means of framing the image.
● A means of holding unexposed film, usually within the body of the camera, in such a
way that it does not become exposed to light; this generally means that the camera film
is supplied in short lengths due to space limitations.
● A means of holding the camera steady whist filming.

THE PROJECTOR Whilst having some similar requirements to a camera, the
projector has some important differences and this is where the compromises come in -
Items one and two above are essentially the same in a projector – certain ‘niceties’ such
as a multiple pin claw and feed and take-up sprockets to assist with the handling of large
size reels of film are desirable.

● The shutter design needs to be quite different to that of a camera. The camera shutter
is designed for best light transmission and generally has a closed segment of about 40%
of the pull down cycle, with an open segment of about 60%. The shutter has one ‘open’
segment for each frame of film transported through the gate. If such a shutter were used
in a projector, a flicker rate equal to the frames per second (FPS) that the film is running
at would result; at a silent speed of 16 FPS, this would result a severe flicker. For
acceptable projection, the flicker rate should be around 50 per second. At silent speed,
this can only be achieved with a three-blade shutter, a two-blade shutter is suitable for
sound speed of 24 FPS..
● A light source to illuminate the film for projection.
● A means of holding the film to be projected, possibly in lengths much greater than
that originally exposed in the camera, to allow the original camera films to be joined for
a longer presentation.

REEL DEALS June 2025 7