PRINTING THE POSITIVE
Theoretically there is no operation in the whole art of cinematography
which is more complex than the preparation of the positive. This is
used for projecting the image on the screen, and is the result upon
which popular criticism is passed. Also, in the process of printing the
positive, several short-comings in the negative can be corrected.
At the same time, from the practical point of view, the preparation
of the positive is simple. The beginner who has mastered the somewhat
intricate process of development, need not apprehend any greater
difficulties than those he has already overcome before he essays to
print his positive. In practice he will soon become proficient, though
he may retain rather hazy ideas of the theory of the matter.
The essentials for the preparation of the positive are a printing
machine and an illuminant. The appliances and methods of operation
differ completely from those used in any other branch of photography,
so that a new art virtually has to be mastered. Fortunately, the
beginner gets assistance from those masters of the craft, who, having
left the producing for the manufacturing side of the industry,
willingly give advice to the tyro. By following the few rules which
these early workers lay down, the beginner will not go far wrong, and
will not run the risk of incurring many dispiriting failures. While the
large professional firms use elaborate and costly printing machines,
the amateur is able to get just as good results with simpler and
cheaper apparatus. He could not wish for a better equipment than the
Williamson printer, which costs only £4 10_s._ ($22.50), or the Jury
Duplex, which is a combined camera and printer.
So far as the illuminant is concerned this depends upon circumstances.
In most towns it is possible to obtain electric light, which is the
simplest, and taken all round, the most reliable and satisfactory
illuminant. If this is not available, gas and an incandescent mantle
may be used. Failing either of these conveniences, acetylene or petrol
gas, the latter with the incandescent gas mantle, can take their place.
Even daylight may be used.
Success in printing depends upon a correct judgment of the intensity of
the light, and of the density of the film. This enables one to estimate
the exposure required. Obviously this knowledge can only be acquired
in the school of practice. The same experience is needed to estimate
the length of the exposure in making lantern slides, or in bromide
printing. But it must be borne in mind that in the cinematograph film
one is working with a much more sensitive emulsion.
A very good practice for the beginner is to make experimental exposures
with short lengths of film--say 12 inches--making the tests with
sections of the negative which vary in density, at various distances
from the light, and at different speeds. A careful note should be
made of each trial. In this way one can estimate the exposure and
learn how it should be varied at different points of the negative
where the density varies. Moreover, the knowledge will be acquired at
comparatively little expense.
If the negative has been over-exposed or over-developed, or both, a
common error in the first attempts, it will naturally be very dense,
and will demand a longer exposure, or a more powerful light, than a
negative which is exposed correctly. This situation may be met either
by slowing down the process of printing, or by bringing the light
nearer to the film. On the other hand, if a negative is under-exposed
it had better be destroyed at once, as it is worse than useless. An
over-exposed negative will yield a passable print, possibly somewhat
harsh, but nothing can be done with a negative which is deficient in
detail. The only exception that may be made to this drastic policy is
the topical film, which may have been taken under adverse conditions,
during a fog, or in heavy rain, or on a dull day, or at a late hour
when the light was bad. In the topical film it is more the interest of
the event than the quality of the film that is important.
For absolute simplicity it would be difficult to excel the system
adopted in the Jury Duplex camera. In this case one obtains both camera
and printing apparatus--without the lens--for the modest outlay of £8
($40). There is a small bracket mounted upon the outer top face, and
near the front edge, of the case. This bracket carries the spool on
which the negative film is coiled. This is slipped on the bobbin and
locked in position by means of a small lever. The film is carried from
this spool between two small guide pressure rollers and fed into the
camera through a slot faced with velvet, like that provided in the dark
boxes. The film is pulled down a sufficient distance to enter the gate
so as to secure engagement by the claws of the camera mechanism. In
threading the film care must be used to bring the emulsion side facing
the dark boxes and the glossy side facing the lens.
The positive film is inserted in the unexposed film-box of the camera
and is threaded up as if for taking photographs. As the emulsion
side is uppermost, when the unexposed film meets the negative in the
gate, the two films are brought together with their emulsion sides in
contact. As one film is laid squarely over the other, and with the
perforations in line, it will be seen that the claws engage with both,
so that the two films are jerked together intermittently through the
gate.
Emerging from the gate the two films part company. The exposed positive
ribbon passes into the exposed dark box, while the negative film passes
through another velvet-lined slot in the bottom of the camera, and then
is wound up on another spool.
It will be seen that in this case printing is carried out in a manner
similar to photographing. The film is run through the camera in the
ordinary way by turning the handle, and the number of exposures per
second can be varied within wide limits to suit the density of the
film. The camera is supplied with a second spindle and gearing upon
which the handle may be slipped. The ratio of this gearing is one
exposure per revolution, or as it is termed "one turn per picture."
Owing to the positive film being contained within the camera, and
therefore in a light-tight space, the electric light or other
illuminant may be mounted upon the bench within the dark room, so that
the operator can work in a lighted apartment. In this arrangement,
however, the camera should be clamped firmly to a rigid foundation, so
that it may not move during exposure. This also ensures that the light
should remain at a constant distance from the machine.
This camera can be adjusted easily and cheaply for the purpose of
daylight printing. All that is required is a square funnel, about two
feet in length, made of wood and so designed that the smaller open
end fits into the front recess of the camera after the shutter panel
is removed or opened. This funnel should be made after the manner of
a Kodak enlarger, and blackened on the inside, with a dull medium, so
that no reflections of light are set up. When this funnel is attached
it is only necessary to stand the camera on its rear face so that the
opening of the funnel points directly to the clear sky overhead, not
towards the sun, and to turn the handle upon the one turn one picture
gear. The printing speed will vary with the intensity of the light and
the density of the film. Obviously the camera can be run more rapidly
on a bright summer than on a dull winter day. In the first case it is
safe to turn the handle as fast as possible, but in the second the
speed would need to be about one picture, or handle turn, per second.
[Illustration: THE WILLIAMSON PRINTER.
(For explanation see p. 85.)]
[Illustration:
_From the "Cinema College," by permission of the Motograph Co._
WATER BEETLE ATTACKING A WORM.]
One advantage of this system of printing is that the picture is
printed with the camera with which the negative was obtained, and so
first-class results are inevitable. The registration is assured as
well as the alignment. In threading up the camera it is only necessary
to make sure that the image on the negative comes squarely and truly
before the window in the gate. Once this is so, every successive
picture must be in perfect registration and alignment. There could
be no method of printing more suitable for those who are travelling,
or engaged on topical work, often under trying conditions, for the
conversion from photographing to printing, and _vice versâ_, may be
accomplished in an instant. Some of the more expensive cameras costing
from £20 ($100) upwards are now fitted with a printing attachment, the
printing accessory being detached when the instrument is being used for
photographing purposes. These cameras follow where the Jury Duplex led
the way.
The Williamson printer works upon a different principle, being a
distinct and separate machine. Nevertheless it is an eminently
practical appliance, and is as well adapted to the factory as to the
amateur's dark room. It comprises a base board on which the whole of
the mechanism is mounted, together with the stand for the light. (See
illustration facing page 84.)
In this installation there must either be a dark box to contain the
light, against the face of which the base board of the printing
mechanism is screwed, or else an aperture must be provided in the wall
of the dark room and the light be placed on a shelf outside. The handy
man, however, will be able to devise a light-tight box, either for
the electric light or gas. In the latter case it must be fitted with
a chimney with baffle plates absolutely light-tight, to carry off the
products of combustion. The light-tight box should be lined either
with absolutely safe ruby fabric, or with orange and ruby fabrics
superimposed. If wood is used, the light-box is apt to split under the
influence of the heat within.
The Williamson printer is of the simplest design conceivable. There
is an upper spindle A (see illustration facing p. 84) on which the
spool containing the negative is carried. Immediately below is another
spindle carrying the spool B on which is slipped the coil of unexposed
film. The negative film, emulsion side outermost, as it winds off
the spool A is passed behind the guide roller C and then picks up
the unexposed film of spool B. The emulsion side of the unexposed
film comes into contact with the emulsion side of the negative film.
Passing over another guide roller D the films pass together between
the two rollers E to enter the gate F. The latter is mounted upon
the rear face of a small chamber, the aperture of which is of the
size of the cinematograph film image. This aperture is provided on
the inside with a small hinged shutter. By opening this one can see
that the negative image occupies the full space of the window, or make
any other observations. The film is moved intermittently through the
printing gate F by the sprocket wheel G, the teeth of which engage
with the perforations in the films. The engagement of the films with
this sprocket is ensured by the two pressure rollers H. The sprocket
G is mounted upon and revolved by the handwheel I--a motor drive can
be incorporated if desired--and after being moved beyond this sprocket
wheel, the two films divide, the positive film being wound upon a
spool or into its dark box, while the negative is wound upon another
spool. The movement of the light K, either towards or from the exposure
window F, is effected by means of the handle J, which has ten stops
corresponding to as many different distances. The lamp moves to and fro
along the support L.
It will be seen that the Williamson is a simple, straightforward
machine. It is soundly constructed and works admirably. Its
achievements are in every way equal to those of the complicated
and more expensive model manufactured by the same firm for
professional use.[2] So long as the machine works reliably, and has
perfect registration and alignment, nothing more is required. Extra
refinements, and little details, while of service to the expert, only
serve to harass the amateur.
[2] "Moving Pictures: How they are Made and Worked," Chapter
VIII., page 82.
As a matter of fact the most important duties of a printing machine are
to feed the two films evenly and easily through the gate, and to hold
them flatly and tightly together, so as to secure perfect contact while
they are before the exposure window. By this instrument both these
duties are perfectly performed. The sprocket G continuously revolves
under the steady turning movement of the handle, and the two films are
held rigidly, tightly and steadily together by the pressure gate F.
Of course, in printing with this machine, the operator works in total
darkness, owing to the coil of positive film being fully exposed.
This is no handicap however, because the dark-room ruby lamp supplies
sufficient light to enable the necessary operations to be performed.
But it is not wise to use too powerful a ruby light, or the unexposed
positive film will be fogged.
Turning the driving handle is no more difficult than turning that of
the camera mechanism. The gearing is so designed that six exposures
are made per revolution, representing twelve pictures per second, when
revolved at the normal speed. With a negative of average density this
speed is sufficient. But the period of exposure can be varied according
to the speed at which the handle is turned. The turns of the handle
should be steady and regular, or the pictures will be of uneven density
owing to the variations in exposure.
The electric light is easily moved by means of the handle while the
ten stops give it great flexibility. In order to maintain an exposure
of twelve pictures per second with an average negative, a lamp of 50
candle power should be used. To ensure the best results it should
be of the class known as "focus lamp." This type of lamp has a
special filament, with a smaller coil than is found in the ordinary
incandescent electric lamp. A gas burner with incandescent mantle may
be used if electricity is not available, though the operator will have
to ascertain the relative value of the luminous intensity of the light
as compared with the 50 candle power electric light, and will be wise
if he makes one or two trial exposures with short lengths of film
before essaying the printing of a complete film.
While it is possible during printing to vary the distance of the
light from the exposure window, the light being manipulated with the
left hand, while the handle is turned with the right, there is slight
necessity for such a procedure. The negative film should be examined
to ascertain how the density varies along its length, and then each
portion of film that shows tolerable regularity of density should be
printed off at the same speed. In this way variations of distance need
occur only with distinct lengths of film. This is a far safer method,
especially for the beginner, than the movement of the light to and fro
while the films are running through the gate, though of course with
practice it becomes possible to do the two things satisfactorily at
once. Many amateur cinematographers make the mistake of attempting
artifices which they have seen practised by some experienced
professional worker, and the result is failure. What is easy and simple
to the expert is often beyond the powers of the beginner. Success in
printing can only be achieved by honest and diligent work, but patience
is sure of its reward. At first there may be a tendency to make the
positives somewhat too dense, and then, when the evils of this defect
are appreciated, to fly to the opposite extreme. Of the two blemishes
probably the latter is the worse, as it produces a washed-out effect
upon the screen.
The positive is developed in exactly the same way as the negative,
and with the same solutions. When dry the positive, which may have
been printed in short distinct lengths, should be connected up with
the aid of cement as described in a previous chapter. If titles have
to be introduced they may be inserted wherever required, merely by
severing the film at that point, and introducing the length carrying
the explanation.
The preparation of the titles is a simple matter. If printed type is
used, the letters cut out of white paper or cardboard are laid flat
upon a level surface with a black background. The camera is then placed
overhead with the lens pointing downwards upon the centre of the title
space. The latter, brilliantly illuminated, is then photographed at the
rate of sixteen pictures per second for a period of ten seconds or more
according to requirements.
In many instances, especially in non-topical work, the operator need
not necessarily incur the expense and trouble of printing a positive
film. Many of the purchasers of educational and popularly scientific
films will give their decision after having seen the negative passed
through the projector in the manner of a positive film. So long
as great care is used, this can be done without ill effects, but
of course the slightest scratch or abrasion that the negative may
receive in the process will be reproduced with accentuated effect
upon the positive film. Even with some of the topical films a positive
is not necessary. To submit the negative to the local theatre or
prospective purchaser is often a good way of saving time and being
first in the field. Many theatres now are being equipped with dark
rooms and printing machines. A glance at the negative will enable
the manager to decide whether the film is serviceable or otherwise,
and if a purchase is made, the deletion of the uninteresting parts
can be made before printing. Incidentally, one great advantage of
this is that the film is submitted for consideration about three or
four hours earlier than would be the case if the independent worker
struck off his own positive, and in these days of high pressure such
a saving is important. It may often be the means of forestalling a
competitor. Even if it is intended to supply prints to two or three
different picture palaces the negative offers a means of transacting
business, because the respective establishments can give their orders,
make their arrangements concerning announcements, and be able to judge
fairly accurately the hour at which the film will be available for
projection. In one instance an independent topical worker who had a
first-class negative of a popular subject drove round from theatre to
theatre with his negative and secured an order for about half-a-dozen
copies. He then handed over the work of printing to a professional
firm. Four hours later he delivered the positives to the respective
theatres, and ultimately he sold the negative outright to the firm who
completed his printing contracts for the supply of other markets at
their disposal. In another instance an enterprising amateur who had an
excellent negative handed it over to a topical-film firm to print and
circulate, the firm to take fifty per cent. of the receipts and to bear
the expense of printing and other details.