American cinematographer (Jan-Dec 1931)

Thirty-six AMERICAN CINEMATOGRAPHER June, 1931 Amateur Movie Making (Continued from page 30) the rest of the picture record itself on the film. To do this, we interpose light filters — bits of colored glass or gelatine — between the subject and the film. Photographic light filters are made in a variety of colors, but the ones which we want are those particular yellow ones which will absorb the ultraviolet rays entirely, and much of the violet and blue ones, as well. There are quite a few filters of different manufacture which will do this; but the standard ones are the Wratten "K" series, which come in several shades, and are known as the K-l; the K-IV2; the K-2; and K-3. As they remove the powerful blue and violet rays, without supplying anything to take their places, they naturally increase the exposure needed, •so that the less powerful rays which remain can do their work. They have been scientifically measured, however, and the exact exposure increase for each filter is known. For the sake of convenience, this is called the "filter (or multiplying! Factor". For the K-l, this factor is 1 Vz, which means that the normal exposure (as given by your meter) must be multiplied by 1 Vz. For the K-l Vz, the factor is 2; for the K-2, it is 3; and for the K-3, it is 4Vz. The exact filter to use depends, naturally, upon the degree of haze present, and -the nature and distance of the scene. For most distant landscapes, the K-2 and K-3 are the best, the latter especially. For closer scenes, and for more distant ones on exceptionally .clear days, the lighter filters are more suitable. On the other hand, for extreme telephoto work — that is, with lenses of six inch focal length or over — the best landscapes are secured with an even deeper and sharper filter. Telephoto ■shots are usually characterized by an exaggerated flatness at any time, and for distant landscapes a very sharp-cutting filter will help to correct this. Therefore for such use the Wratten "C" filter is by far the best. It is of deeper, more orange hue than the K-3, but its multiplying factor is much the same, varying from 4V2 to 5. In use with reversal film, where a slight •underexposure is far preferable to a slight over-exposure, the factor had best be taken as 5. Of course, too, with telephoto lenses (or with any fast cine lens, for that matter) it is important that a good, deep lens hood be used at all time, to shield the lens, not only from direct sunlight, but from all light that is not actually being used to make the picture. Most cine lenses come equipped with fairly adequate lens-hoods, but you can hardly go wrong by making an additional hood for your telephoto and speed lenses. In the Mountains Mountain work presents some peculiar problems of its own. As you ascend to higher altitudes, the air becomes steadily clearer, requiring less and less exposure. A good rule to follow is to give normal exposures below the 4,000 foot level; from there to around 5,000 feet, 3A normal; above 5,000 -feet, Vz normal, and so on. Besides this, the clearer atmosphere requires iighter filters, if the proper balance between sky, trees, rocks, and snow is to be maintained. For most mountain landscapes a K-l or K-IV2 will usually be satisfactory, though if there is much color in the foreground, a K-2 is often advisable. For telephoto work in the mountains, the K-2 is also all that is necessary, as the "C" filter otherwise used is too strong, unless there is a bit of haze or fog in the distances. That Bald-headed Sky Another thing that all too frequently detracts from amateur landscape cinematography is the nakedness of the skies. The professional has long since learned that, where landscapes are concerned, clouds make the picture; accordingly, he avoids, whenever possible, photographing a landscape if an unclouded sky is to figure in it. And if professional film companies are willing to delay production until they can get some beautiful clouds to float across the tops of their landscape shots, -the amateur, who is not shackled to an overhead expense of many hundreds or thousands of dollars per day, can certainly do likewise. A few pretty clouds can make a real picture out of an otherwise ordinary landscape, while a "bald-headed" sky can ruin the best view. Clouds, of course, being in the intense blue field of the sky, naturally require filtering if they are to be photographed to the best advantage. The exact filter to use is obviously dependent upon the atmospheric conditions and the type of clouds, as well, of course, as the relation of the clouds to the sun. In general, it is probably best to use a good, heavy filter, like a K-3, although this will sometimes make the sky seem darker than is strictly pleasing. There are also times when it is wise to use a graduated filter, which ranges from a deep yellow at the top, to clear glass at the bottom, thereby equalizing between the sky and foreground. But, whatever filters you use, don't neglect your skies, if you want to get the best landscapes possible! It may often mean waiting a few hours or even days, but it also means the difference between a scene that you will be proud of and one which will remain either a lasting disgrace, or an encumbrance on your cutting-room floor. • Screen of Metal Mesh Placed On the Market AFTER several demonstrations with good results, a new type ^ metal mesh projection screen, under the trade name of "Lustro-Pearl" and designed especially for high grade theatres, has been placed on the market by the Mandaiian Manufacturing Co., North Attleboro, Mass. The advanced features claimed for this new screen include: A surface treated with the purest of known chemicals, entirely free from gloss, eliminating all distortion common to ordinary types. Highest reflection factor known to reputable light testing laboratories, effecting a considerable saving of electric current. Constructed so as to distribute sound very clearly and uniformly throughout the entire theatre. Can be washed with hot water and soft brush without injury to its surface. Affords a clear view of any picture from any angle of observation, eliminating eye strain or discomfort to patrons. Surface may be sprayed periodically for many years, and for this purpose, the company plans to loan for a period of ten years a complete up-to-date spraying outfit with each screen purchased, and furnish chemical solutions from time to time for resurfacing this type screen. Its high reflective qualities bring out objects in a manner which might be termed the nearest approach to three dimensional pictures, the company claims. R-K-0 Proctor's 58th Street, New York, is among the first houses to install this new type screen. Foreign Sales Increase PRELIMINARY figures compiled by the motion picture division of the Bureau of Foreign and Domestic Commerce reveal the fact that approximately $5,000,000.00 worth of American made motion picture equipment was sold abroad during the year 1930. This is an increase of $4,000,000.00 over the foreign sales for 1929, and gives a fair idea of the tremendous sales possibilities for our equipment there are in foreign fields. Among the outstanding items were the following: 2,160 35 mm. projectors, 946 35 mm. cameras, 1,667 cameras of less than 35 mm., and 1,634 16 mm. projectors. Two R-K-0 Features in Color R-K-0 will make both "The Bird of Paradise" and ".Condoning Wives" entirely by the recently improved Technicolor process, it is announced. Paramount also is to make "Rose of the Rancho" under the process.