Reel and Slide (Mar-Dec 1918)

36 REEL and SLIDE J How to Use Motion Picture Camera By J. Frank Martin (Many large manufacturing concerns and educational institutions have installed laboratories and are producing moving pictures on the spot. There have been many requests for information on the subject of motion picture photography. Reel and Slide has arranged with Mr. J. Frank Martin of Pittsburgh, an authority on the subject, to print this series of articles. — Editor.) (Continued from last month.) Correct Exposure THAT the camera reproduces a perfect image of a subject is not true when speaking of colors. This fact coupled with the great adaptability of the eye to a wide range of illumination makes a correct judgment of exposure very difficult and obtainable by careful practice only. The blue component of light rays being the actinic agent it is self-evident that if a light hazy day, on a cloudy day and a dark cloudy day. Each series should be repeated in Winter and Summer and all the readings carefully noted. The results plotted in the form of curves will show some remarkable results. It will be found that a partly cloudy day with light clouds will give the maximum illumination and good light in the early and late hours of the day. Such a series of readings are plotted in Figure 2. Exposure Tables Based on 50 Per Cent. Shutter Opening, System for Summer Months. Use next lower stop in Winter Months. The above exposure tables are based upon the widest shutter openings available and variations in shutter openings are frequently necessary and the stop must be varied to correspond with the shutter opening. The standard stop scale is so 3 S >" s -^ c 36 02 -S mo m ~ >> •r J< c a J5^ "Close Ups" 8A.M 5.6 8 3.5 5.6 5.6 9 " 8 11 4.5 3.5 8 8 10 " 11 11 5.6 5.6 3.5 8 11 11 " 16 16 8 8 4.5 11 12.5 12 N 16 22 11 8 5.6 11 12.5 IP.M 16 16 8 8 4.5 11 12.5 2 " 11 11 5.6 5.6 3.5 8 11 3 " 8 11 4,5 3.5 8 8 4 " 5.6 8 3.5 5.G 5,6 Standard 8A.M 8 11 5.6 3.5 5.6 8 Scenes with 9 " 11 16 8 4.5 3.5 8 8 full size 10 " 16 22 8 5.6 3,5 11 11 figures and 11 « 22 22 11 8 4.5 12.5 16 Dark Land 12 N 22 32 16 11 5,6 16 18 scapes. • IP.M 22 22 11 8 4,5 12,5 16 2 " 16 16 H 5.6 3,5 11 11 3 " 11 11 5.6 4.5 3.5 8 8 4 " 8 11 4.5 3.5 5.6 8 Light 8A.M 11 16 9.5 5.6 3.5 Landscapes, 9 " 16 16 11 8 4 Snow Water 10 " 22 22 16 8 5,6 and Sky. 11 " 32 32 16 11 8 12 N 32 32 22 16 11 IP.M 32 32 16 11 8 2 " 22 22 16 8 |5.6 3 " 16 16 11 8 4 4 " 11 16 9.5 5,6 3.5 Figure III we could always view the subject by blue light only we could at all times judge the illumination and exposure more closely. The writer has put this in practice by using a set of blue spectacles which can be readily secured of any optician. Later this method has been improved upon by substituting a blue focusing screen for the ordinary clear one. By using a focusing card at a uniform distance, then stopping the lense down until a certain degree of visibility of the focusing card is secured on the blue screen, an exact measurement of the illumination of the subject is secured. This method is an adaptation of the Ives Actinometer, a very efficient instrument for the cameraman. What Meter to Use Photographers judge exposure either by instinct or exposure meter. After long experience they rely altogether on instinct. The cultivation of this instinct to a high degree of precision can be obtained by making a series of simple measurements of light under varying conditions. The Watkins "Bee" meter or Wynne meter are suitable for the purpose. The procedure is to take a series of readings every half hour from early morning until late evening. Take one series on a bright clear day with sunshine, another on marked that each number below gives twice the exposure. Moonlight and Sunlight Effects are CHA^RT OP asHT rssrs tv/r// e'ee ^ere^ Figure II NOTE: — Intermediate numbers not indicated in stop scale are used above and estimation of correct position will be necessary and will have sufficient accuracy. secured by pointing the lens directly toward the sun and focusing with the image of the sun directly in the center of the field. Exposure should be made with onehalf to full shutter opening on a "F" 22 stop. To prevent possible flare and halation an "X" 3 ray filter should be used and exposure made at 1-3 normal speed unless rapid action is had in the subject, when stop ''F" 9.5 is correct. Tinted Scenes for Night Effects should be made in the bright sunlight with the sun to one side of the camera. Slight under exposure should be the rule, the idea being to secure pronounced shadows, which is a natural moonlight effect. Silhouettes Under Exposed Photography at Night is at best a poor undertaking except with strong artificial light. Creditable effects are to be secured by taking two exposures of the same scene about three hours apart. The first exposure is made by daylight greatly under exposed leaving the camera absolutely stationary and making a stop exposure after night. Silhouettes have certain artistic adaptations and are made by great under exposure. The writer has used this type considerably and in doing so has developed the "Silhouette Hood" shown in Figure 4, which allows of exposing for silhouettes with any desirable background. The arrangement is very simple and is portable. Buy Liberty Bonds