American cinematographer (Jan-Dec 1932)

The Conning Eclipse And S ome Timely Advice on Photographing It by CHARLES C. CLARKE, A.S.C. THE eyes of the scientific world are now being riveted upon Eastern Canada, Vermont, New Hampshire and Maine because of the total eclipse of the sun which will be visible in that region on August 31, 1932. Many parties from observatories will be making records along the path of totality, and scores of professional and amateur photographers will be getting cameras ready for the eventful day. We often witness an isolated cloud casting a distinct shadow on the surface of the earth while the sun is directly illuminating the landscape around the spot. If the cloud is in motion, the shadow will move. This is, in reality, a miniature eclipse of the sun. In the real eclipse such as we will see the last of this month the moon takes the place of the cloud and totally obscures the sun. Of all celestial phenomena, none have in the past made so deep an impression upon the minds of men as has the total eclipse of the sun. Often it has been looked upon as something supernatural, a direct manifestation of Divine wrath. Mathematical science may have banished this superstition, but the spectacle is still one to impress the beholder. The earliest record of an eclipse is reported in an ancient Chinese classic, "Shu Ching," as taking place on October 22, 2137 B. C! Another was visible in southern Babylonia on July 31, 1063 B. C. The successful prediction of an eclipse is really a triumph for the mind of man, and one of the test questions put to nature, on the reply which depends largely in the certitude of truth and conviction of reality. I do not know of any department of science where man has made more glorious conquests. For example, it is known now that there will be a total eclipse of the sun visible over Paris on June 4, 2160, long after you and I have passed on. So accurate is mathematical astronomy in predicting eclipses that the eclipse which will be visible at Los Angeles on August 12, 2045 is so well understood that we could set our cameras and instruments now with absolute pre cision. Future eclipses now predicted include one on February 14th, 1934, visible in Borneo; June 19, 1937, visible in Peru. There are three types of eclipses: total, annular and partial. Due to the fact that the orbits of the earth and moon are both ellipses and not circles, the distance between the sun, earth and moon will vary considerably and the length of the moon shadows will change proportionately. Thus, when the sun is close and the moon far from the earth an annular eclipse is produced. When the reverse we have a total eclipse. In an annular eclipse a ring, or annulus, of light appears around the edge of the moon; such an eclipse is shown in Figure 2. The sun is seen gleaming through the valleys of the mountains of the moon, producing these spots of light which are called Bailey's Beads. At the time due for the eclipse there will be found upon looking at the sun through smoked glasses, or black photographic film, a small nick in the north-west side. This is produced by the moon as its east side starts between the earth and sun, the moon starting to hide the disk of the sun. After an hour has passed the sun will appear as a crescent with the horns of the crescent towards the north-west. An interesting effect may be noticed at this time. If the observer is standing near a tree where the sun-light filters through the foliage, it will be seen that every little spot of sun-light on the ground is in the form of a small crescent. The small openings between the leaves are as pin-hole cameras and produce optical images on the ground of the eclipsing moon and sun. About ten minutes before totality the darkness begins to be quite pronounced. The disappearing light becomes changed in quality; it has a pale, ashen hue and differs from sun-light of normal conditions. The landscape, mountains and ocean have a peculiar, unearthly pale appearance that cannot be discerned at any other time. Meanwhile, the surrounding country becomes darker and darker. Sometimes as early as five minutes before the time of totality 12 Fig. 1. Total eclipse, showing Corona. Fig. 2. Annular eclipse, showing Bailey's Beads.