Practical Cinematography and Its Applications

by Frederick Arthur Ambrose Talbot

One of the most fascinating fields in the whole realm of animated photography is the filming of the infinitely small by the aid of the microscope. In this manner it is possible to catch glimpses of bacterial and microbic life in natural movement, and to throw them upon the screen, where the extreme magnification enables one to follow with ease the motions of a living world invisible to the naked eye. Furthermore, the representation upon the screen is clearer, brighter, more detailed, and easier to follow, than any image seen directly through the microscope. There is an absence of that distortion and unnatural motion which often occur when the microscope alone is used.

Micro-cinematography may be either costly or cheap. As the operator in a well-equipped laboratory is able to use a camera costing £100 ($500), it is only natural to suppose that he will also be able to command the services of the most expensive type of microscope. On the other hand, the independent worker, forced by circumstances to be content with an inexpensive camera, will have to do the best he can with an inexpensive microscope also. Yet the investigator of each class can accomplish excellent work in his own sphere. I have seen some very fine films of microscopic subjects which were taken with an instrument costing less than a sovereign. From the general point of view they compared very favourably with those obtained with an instrument twenty times as costly. So long as the amateur does not attempt to embark upon work which is beyond the capacity of his microscope, and is content to work with subjects of relatively large size, there is no reason why he should not be able to take most interesting pictures.

In the preparation of micro-cinematographic subjects it is essential that the instruments should be mounted upon a solid base, a heavy bench or table, so that vibrations may be as slight as possible. The camera may be turned by hand or driven by an electric motor through belts and pulleys.

The method of mounting the microscope in its relation to the camera may be varied according to circumstances. In the simplest form the microscope is mounted horizontally with the stage on which the subject is placed set vertically, the subject itself being in line with the middle of the cinematograph lens.

In working with the microscope it must be remembered that the objects are seen by transparence. That is to say, the ray of light passes directly through, or around, the object, causing it to stand out darkly upon a luminous background. From this arises one of the limitations of the microscope. If the subjects themselves are wholly or nearly transparent, they become wholly or nearly indistinguishable in the illuminated field in which they are placed. In still-life microscopical study this disadvantage is overcome by colouring the glass slide on which the subjects are deposited, but in cinematography this operation is ruinous to the work for the simple reason that the aniline dye used to colour the slide kills the microbe whose life and movements are to be observed.

It must not be forgotten that very small organisms, as a rule, move at a speed which is quite disproportionate to their size. Some will dart hither and thither across the field of the microscope with the speed of lightning, while others will move with great deliberation. In the first case a photographing speed of sixteen pictures per second will scarcely suffice to give a faithful record of movement. The result will be a series of disconnected jumps. On the other hand, if the object moves slowly, a photographing speed of sixteen pictures per second may be too rapid. In this event the phase of movement between two successive pictures will be so slight that the projection on the screen will appear tame unless the express object is to indicate the slowness with which the organism moves. And indeed this object can be achieved with almost equally good results by taking the pictures at a slower speed, say eight, four, or even two images per second, and thus saving a good deal of film.

In most cases the micro-cinematographer works in a state of ignorance. He does not know whether he is obtaining a good or a bad film. His subject may be moving, or it may be quiescent, or it may hover round the extreme edge of the luminous field, in which case the pictures will be useless. When Mr. James Williamson and Dr. Spitta were engaged on micro-cinematograph studies some years ago, they introduced a means of following the subject through a second tube, and in this way were able to make certain that the camera was working only during those periods when the subject was in full activity, near the centre of the picture. In this way a considerable saving in film was effected.

By courtesy of the Marey Institute.

Micro-cinematograph used at the Marey Institute for Investigating Minute Aquatic Life.