Movie Makers (Jan-Dec 1930)

CIB 55312 MAXmiEIES JANUARY, 1930 WITHIN FOUR WALLS A Discussion Of The Fu7idamejitals Of Interior Lighting No owner of a cine camera can enjoy the fullest possibilities of his equipment until he has taken up interior work. It is a bit difficult to produce a successful amateur photodrama without using at least a certain number of interiors but it is very easy to produce such a complete film without ever taking the camera outdoors. Amateurs who have never tried this fascinating work seem to think there is something unusually difficult about interior work but, as a matter of fact, these difficulties are largely imaginary. Provided with a few additional items of equipment, any amateur will find it just as easy to make interior shots as it is to work outdoors. The first desirable item of equipment is a lens of high aperture, such as the /:1.5. Not only does the high aperture of this lens make possible a full exposure when using less light than would otherwise be required but it also possesses the very distinct advantage of a shallow depth of focus which adds materially to the artistic results obtained. It is true that such lenses require somewhat more care in focusing than lenses of smaller aperture but the focus is not so critical that any real difficulties are encountered. In using this lens with comparatively close subjects, one should understand the correct use of differential focus. As a rough guide, we may assume that, when a lens is sharply focused upon a given point, the depth of focus is divided into three parts, two parts of which lie behind the point of principal focus and one part in front of it. On closeups, for example, the cheekbones should be focused. This will give sufficient depth of focus to render all features of the face sharp, while the back of the head will start to become slightly diffused and, naturally, the background will be highly diffused, which is always desirable in closeup By Herbert C. McKay work. When working at distances of twelve to fifteen feet or more from the subject, a background four or five feet away, such as would ordinarily be encountered in most interior sets, will be just sufficiently diffused to give a distinct separation of picture planes which is, of course, necessary to the best pictorial effects. Naturally, some source of light must be provided, either arc or incandescent. With the latter type, there seems to be a great deal of confusion regarding the bulb best suited for this work. There is only one really efficient type of incandescent bulb for use in motion p ic t u re photography and this is the p r o j e c tion type of bulb ordinarily designated as the type T-20. These bulbs are most widely used in the 400-watt, 500watt and 1,000watt sizes. Ovnng to the fact that they are made for the express purpose of supplying the most intense incandescent illumination possible, they burn at a very high filament temperature. This means that the emitted light has a far stronger blue component than other types of incandescents. Practically all house-supply current has a normal pressure of 115 volts. If the T-20 lamps are to be used on a direct current supply, the bulbs selected should be 110 or 105 volts. If. however, the current supply is normally 115 volts alternating current, bulbs rated at 100 volts should be used. The bulbs which are rated for use with a lower current than that actually available are called high pressure lamps. The reason for using them is the fact that the higher voltage than the lamp rating calls for increases the actinic emission to a very marked degree. Photographically, a 500-watt high pressure bulb will give practically the same results as a 1,000watt normal pressure one. If the arc lamp is used, the actinic emission will be found to be very high. The source of light is, of course, concentrated in a small area and the user of the arc therefore should pay special attention to the placing of reflectors of the proper size as. thereby, the intense illumination of the arc may be turned back on the subject and utilized to its fullest extent. Use of the so-called "panc h r o m a tic carbons" is recommended in conjunction with panchromatic film, giving an excellent rendition of the color values in the scene in black an J white. Filters should never be used for amateur interior work but the light from an arc lamp of this type is really self-filtering and will give results. The surface of the reflectors provided for either type of illuminant should be of such nature that it is really permanent. Satin finish aluminum is perhaps one of the best permanent reflecting 15