Practical Cinematography and Its Applications

by Frederick Arthur Ambrose Talbot

Marey also evolved a means of adapting the camera so as to enable him to take the pictures at a speed exceeding sixteen per second. He did not change the mechanism of the camera very radically, but was able to secure as many as one hundred and ten pictures per second. His arrangement of the camera was very simple, as shown on the plate opposite. The film travelled intermittently, its arrest for each exposure being very abrupt. In the camera were two cylinders C and C¹ between which the film passed, and these cylinders revolved in opposite directions and towards one another. As the two peripheries of the cylinders were brought together the film was gripped and was moved forward by friction, somewhat in the manner of the clutch-action which was adopted in the very first moving-picture cameras. But each cylinder was provided with eight flattened sections, of equal length, disposed equidistantly. Consequently, when two opposing flat surfaces came together the grip on the film was momentarily released, and the film stopped, though the cylinders continued their rotary motion. By the incorporation of gear trains the number of revolutions could be varied up to about seventeen or eighteen per second. In the camera, above the lens was a small device whereby the sudden and complete stoppage of the film was assured during the periods when it was not gripped by the cylinders below. Another similar device was introduced at F above the window, through which the mechanism at the gate was visible, and this also pressed lightly upon the film to counteract all the vibrations set up from its quick intermittent movement. The unexposed film was mounted upon a spool in the removable box R in the usual manner, but before being fed into the camera it passed between two other friction disks D and K, and was then fed through the camera mechanism and out at the bottom into a second removable spool box L, where it was wound in after exposure. This lower box also contained two friction disks similar to those in the unexposed film box, and the larger of these cylinders in the lower box, like D in the upper or unexposed box, was driven by the revolving handle, through belts and pulleys.

It was a very simple apparatus. Although it was open to the objection that the film might slip while photographs were being taken at high speed, Marey proved strikingly successful in his use of it, his pictures being wonderfully steady, even when taken at a speed of one hundred and forty per second. In photographing the beat of a pigeon's wings he secured a complete cycle of motion in eighteen pictures, which, by reference to the chronoscope visible in the same field, shows that they were recorded in three-twentieths of a second.

Such an adaptation of the camera could be used successfully to-day for what might be described, somewhat paradoxically, as slow rapid movements. But it would be better to secure a more positive and simple means of moving the film forward. Of course the main advantage of the friction disk system is that the film suffers no damage as it moves. In an ordinary camera, working on the conventional claw principle, there would be a tendency to tear the perforations when the pictures exceeded sixty or so per second, and it would prove difficult in some instances to ensure the absolute quiescence and steadiness of the film during exposure. With the Geneva stop system of moving the film, a steady smooth movement is more easily obtained than with the claw mounted upon a sharp eccentric.

For such work where there is no desire to exceed two hundred pictures or so per second, the ideal camera is that which has been perfected by Monsieur M. P. Noguès, of the Marey Institute. In general appearance this camera resembles the ordinary machine. It was designed specially for the purpose of field work, for which Monsieur Bull's camera is not suitable. In Monsieur Bull's camera the illumination is effected by means of the electric spark, and it is impossible by this means to light a large field.

Fig. 8.—Mechanism of the Noguès camera, wherewith up to two hundred and forty pictures per second can be taken.

In Monsieur Noguès' camera there are two claws, each mounted upon its own eccentric, and the film passes between them. The claws do not work together. That is to say, they do not engage the film simultaneously on both sides, but work alternately. When one is engaged with the film the other is in the out position. Without entering into a technical description of the mechanism it may be stated that there is an articulated lever system, so designed as to give the claws an irregular D-shaped trajectory, which is very rapid and abrupt, the ascent of the claw to re-engage with the film being sharper and quicker than is possible in the orthodox design. The general design of the claw mechanism and its method of operation may be gathered from a reference to [Fig. 8], wherein the paths described by the moving parts are indicated clearly. The handle whereby the camera is operated is turned at the normal speed of two revolutions per second, but this, owing to the gearing, causes ninety or more downward jerks to be imparted to the film F during each second. This makes one hundred and eighty film movements by the two claws per second, and consequently one hundred and eighty exposures.

Notwithstanding the high speed at which the celluloid ribbon is moved through the camera, there are no signs whatever of tearing. Furthermore, the film, during the brief period of exposure—from 1/360th to 1/480th part of a second—remains perfectly steady and quiet in the gate.

The first camera built on this principle had a maximum speed of one hundred and eighty pictures per second, but by modifying certain details it was found possible to increase the velocity in a subsequent machine to two hundred and two hundred and forty pictures per second. This represents a far higher speed than has ever yet been attained with the ordinary moving-picture apparatus. The machine is no larger than the ordinary type, although, owing to the rapidity with which the pictures are taken, the externally fitting film-box system is adopted, so as to provide a supply of about 700 feet of film for exposure.

In projection on the screen the speed is reduced to about one-twentieth or more of the rate of the exposure. The results are far superior to any which have yet been seen upon the screen. The movements are steadier and more continuous, inasmuch as the proportion of lost movement is about one-twentieth of what it is with the orthodox instrument. The result is that one sees upon the screen many phases of movement which otherwise escape detection or are only partially shown under present cinematographing conditions. Owing to the gearing and the balance of the moving parts the operation of this camera is not more fatiguing than that of the ordinary instrument; indeed, it runs far more easily and lightly. The camera has been evolved for the express purpose of reinvestigating many of the studies conducted by Marey, which, owing to the imperfect appliances at his disposal, are possibly incomplete.