US1963342A - System and method for printing motion picture films - Google Patents

Description

June 1934- D. A. WHITSON ET AL 1,963,342

SYSTEM-AND METHOD FOR PRINTING MOTION PICTURE FILMS Filed Oct. 10, 1927 2 Sheets-Sheet l I M Q):

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SYSTEM AND METHOD FOR PRINTING MOTION PICTURE FILMS Filed Oct. 10, 1927 2 Sheets-Sheet 2 ATTOAZA/E) D. A. WHITSON r AL 1,963,342

- Patented June 19, 1934 UNITED STATES PATENT OFFICE SYSTEM AND METHOD FOR ram'rmo MOTION morons: FILMS Application October 10, 1927, Serial No. 225,365

1 Claim.

This invention relates to motion picture films, and especially to the manufacture of film positives that are used for projection purposes.

In order to obtain a clear idea of the purposes and objectsof our invention, it is desirable to point out briefly the methods in use today in the various steps of producing a satisfactory film for projection purposes. In the first place, the cameraman, operating a camera, secures exposures of a series of scenes, on negative films. These are developed, and from them can be printed the desired number of positive films which are used for projection purposes.

Now let us consider the problems the cameraman must solve. The scenes change rapidly; from indoors to' outdoors, from close-ups to long shots; and each scene thus has a light value that is diflferent from the others. The cameraman in order to secure a good negative, attempts to compensate for these varying light values by ad justing the opening of the lens in the camera;

but it has been found in practice that the negative thus produced still has undesired departures from the desired degree of translueency. Contributing factors may be the inherent and unavoidable variations in cranking speed; or errors in developing.

At any rate, it is well-known that usually if such a negative having a plurality of scenes is printed uniformly (that is, all scenes on the negative subjected to the same intensity and duration of illumination during the process of printing), then at least some of the scenes will be--,

found to be of an inartistic nature; and this is apt to occur even if the negative film exposures are substantially correct. The practice accordingly has been to print the negative non-uniformly; that is, some scenes on the negative may be subjected to a greater duration of printing, or illumination during printing, than other scenes. The extent of this variation in printing intensity is usually merely a matter of guesswork and of personal judgment. Since such judgment is grounded on trail human nature, it is not at all surprising that some scenes must be printed over several times before the desired pictorial effect is produced. This item alone, involves the loss of huge sums, for not only are the films wasted, but the time and operating expense involved in producing these discarded films.

In the judgment required to determine the time of printing or the intensity of the illumination during printing, the attempt is made to obtain a desired artistic illumination on the screen when the film is projected. This involves a decision about the desired light transmitting properties of the printed positive film; and this must be translated into terms of printing time and printing illumination when the negative is printed. In the iollowing description and in the claim, the term translueency will be used to designate these light transmitting properties, both for the negative and for the print; and in this way, a concise expression can be used instead of the unwieldy one that is perhaps more accurate.

With the aid of our invention, it is possible to determine the intensity of printing precisely and rapidly without the introduction of the human element. The term .intensity of printing is intended to mean the duration of printing, or the intensity of illumination used for printing, or the combination thereof. Since great quantities of film footage are printed every year in the motion picture industry, the consequent saving in expensev due to the use of our method is very large.

In most scenes, the interest is usually localized at a definite place of the "frame (this term referring to a single unit picture); ordinarily, it is about at the center of the picture, but .occasionally it may deviate from this position, such as when the main character or characters move about. The artistic sense or feel is best satisfled when this focus of interest is desirably or artistically illuminated on the screen; that is, when the translueency of that portion of the frame is correct; and it is more or less a matter of indifference whether the rest of the frame is as correctly illuminated. It is another object oi our invention to make it possible to secure this artistic or desirable effect as regards the center of interest (irrespective of its position in the frame), in a precise and simple manner, and without the necessity of the exercise of trail human jud ment.

Our invention possesses many other advantages, and has other objects which may be made more easily apparent from a consideration of one embodiment of our invention. For this purpose we have shown a form in the drawings accompanying and forming part of the present specification. We shall now proceed to describe this form in detail, which illustrates the general principles of our invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of our invention is best defined by the appended claim.

Referring to the drawings:

Figure 1 is a diagram showing a system by the aid of which our invention can be practised;

2 deta grain of a section of a negative and the means whereby the center of interest of the frame can be used to determine the printing intensity; and

Figs. 3 and are general front and side views of one form apparatus that is used for practicthe invei The system 1. clves in general th provision or a device that responds to the translucency of negative, or least, selected portions of the negative. The translucency of any such portion can then be compared with a definite desired standard in a manner to he later described; and the quantities cor ponding to these relative translucencies can be utilized to determine the printing intensity. For nroviding a uniformly good print, each scene 1e negative should be subjected to s measuring process at least at one or two frames included in the scene. The term scene is used herehi in the usual technical sense; that a series of frames or individual pictures in which the exposures were produced in rapid succession, and usually implies that the same scenery is used for all such frames.

Thus in we show a pair of reel mechanisrns and l which merely form a convenient means ror passing th negative 13 across a table or support whereby the translucency of parts of the can be determined by apparatus located adjacent the table. Guide rollers 15, M

can he provided desired to maintain. the 5.11.1 is in .0 .l

proper relation. the table.

In order to provide an indication the "e" tive translucency or any portion of film t is a source of light 17 which is arranged to direct light against him 23, and the light transmitted thereby serves to actuate a light responsive device to he later described. The light 1! can cor venientiy he an electric light, supplied with 815.1- rent from an electric circuit including a source, such as battery Since for accuracy it is de" sirable to have as miforzn light as possible, the current supplied by source 1 is arranged to be accurately regulated by a variable resistance 19; the voltmeter 20 is provided and is connected across lamp 1? to furnish a check upon the lamp energization. Furth rmore, special care should he taken to ensure good contact betwe n the lamp 1'? and its socket.

Preferably there is provided a curved reflector such as 21 for focusing the light upon an arrangenient whereby the rays stay parallel the ilhimination is uniform; such as a condenser lens 22. The table has aperture 23 therein permitting the passage of the light through nun The light is then caused to afifect a device that translates light energy into a readily measurable energy, such as electricity; for example, the light can be trained as converging lens 24- onto photoelectric cell 25.

A photoelectric cell such as 25 usually has a pair of spaced electrodes located in an appropriate transparent container, and having such a property that there is an electronic emission from one, such as the cathode 26, to the other such as the anode 27, whiclrvaries with the amount or" illumination to which said cathode is subjected. Such cathodes are now well known, and usually consist of a metal plate coated with a compound or amalgam of the alkali metal group. These electrodes can be connected to an external circuit, in which there is included a source of potential such as battery 28. This battery has its negative terminal connected to cathode 26; and

Vii. v;

its voltage is as in "ii/hen there is variation in illunil' ion, there is a correspondin variation in electronic emission electrode and consequently there is a variation in the cu ent fro 2 external circuit connecting e electro es. current responsive device so." l as a galvanoineter 29 can be included in the circuit to provide a1. -m. the relative illumination values. This in is preferably inicroammetcr, s ce th variations of course small.

variable shunt l. fiat 15121.1

the lig t responsive device possible ea"-" he manner of use ou nvebe more carefully detailed. -iere'nce with which the film ti nsluc be compared, initially the syster passing light fro lamp th' which has a st card t'anslucen desired to maintain in the course negative is not at this ta'cle the light encounteri; o of; screen ill. The resistance l justed so as to maintain lain ndard value whic". is to be 1" tnieasureinents. LlkBWlSc device 25 cl by The light pas Jedance of cell from cathode ates a passage carefully inanipulat medial value on b arbitrarily assigned a nuin' dicating the standard or desired cency of Now screen as AS moved o handle 32, negative sses eve 14;. Two or three frames of eacl' over aperture for a period nut the apparatus to 1 no it is often desirable to measu lucency of only a portion of the center of interest of frame. The relative position of the iris and frame under test is diagrammatically illustrated in Fig. 2. ihis iris being spaced some distance lad above film 13, has the effect of gradually shading off the light around the edges of the illuminated portions of th frame under test; this is desirable from an artistic standpoint. It is of course possible to secure the same effect by grading the iris density. Irises that have increasing densities as the edge of the opening is approached are well-known, and can be utilized for this purpose. For example, the iris opening, instead of being a smooth circle, can be star-shaped or can have other variant forms, forming more resistance to the passage of lightadjacent the edges. The same effect can also be obtained by placing the iris at such a point in the optical system as to serve partly as a diffuser of light. When an iris is thus used, the apparatus must be readjusted to agree with the amount of light that can pass through the iris.

As before stated, two or three scattered frames g 'of each scene can be subjected to the operation of the apparatus, a record being kept for each scene. The translucency of the frame under test determines the quantity of current flowing between electrodes 26 and 27. If this translucency is greater than that of the standard screen 31, the microammeter 29 will be deflected further than the index 8, and a record is kept of this for the scene under test. On the other hand, if the translucency is below that of screen 31, the pointer of microammeter 29 will indicate some figure diflerent from 8. For convenience in indexing or recording, it is advisable that for translucencies less than standard, the reading be larger, to indicate the necessity for greater intensity of printing; and conversely, for translucencies greater than standard the reading should be less. Thus galvanometer 29 will have an inverse reading scale, the larger numbers corresponding to a smaller deflection. Periodically it is advisable to try screen 31 and to note whether the instrument 29 will indicate the desired standard value, for such influences as temperature or the like may cause undesired, even if minute, changes in the readings.

The numbers noted for the scenes as thus described are associated with printing intensities in an inverse manner. Thus the higher the translucency, the lower should the printing intensity be. The exact calibration between relative translucence as thus determined and printing intensity can be empirically determined and tabulated or plotted. Thus no guesswork or human judgment is needed for the printing of negatives.

While the apparatus is not in use, it can be easily rendered inactive by the opening of switches 34 and 35, in the lamp circuit and in the measuring circuit respectively.

In Figs. 3 and 4 one practical embodiment of the device is illustrated. A convenient stand or support 36 can be used, upon which the table 14 is located. Beneath the table is a compartment 37 for the photoelectric cell 25; and on each side thereof there are the reels 11 and 12. The galvanometer or microammeter 29 can be conveniently mounted on the front of a sloping panel 38, as well as any other instruments such as 20 and 31 that may be desired. The lamp structure 21, 22 can be conveniently supported over table 14 as by a horizontal arm 39. The switches 40 for controlling the various circuits can also be conveniently mounted on table 14. If desired, a footage counter 41 and scene counter 42 of any desired form can also be provided.

It is, however, evident that the basic ideas of our invention are in no wise dependent upon any particular mechanical arrangement, the form illustrated being merely one that has been tried out successfully. ments can readily be provided.

We claim:

The method of producing a motion picture print from a negative that has scenes therein in which the translucencies deviate from one another and from a desired translucency, which comprises transmitting light of fixed effective standard intensity through a portion only of at least one frame in each scene, said portion being centralized at the center of interest of the picture in the frame, obtaining an indication of the relative translucencies of said portions, and printing said scenes with an intensity determined by said relative translucencies.

' DELMAR A. WHITSON. LEWIS W. PHYSIOC.

Other mechanical arrange-

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