Additive 2 color: Alternating filters, 16 mm
Original Technical Papers and Primary Sources
Dubray, J.A. (1933): The Morgana Process. In: Journal of the Society of Motion Picture Engineers, 21,5, 1933, pp. 403-412.
Brown, Simon (2012): Technical Appendix. In: Sarah Street: Colour Films in Britain. The Negotiation of Innovation 1900-55. Basingstoke, Hampshire: Palgrave Macmillan, pp. 259-287, on p. 277.
Heymer, Gerd (1943): Die neuere Entwicklung der Farbphotographie. In: Ergänzungswerk zum Handbuch der wissenschaftlichen und angewandten Photographie. Wien: Julius Springer 1943, pp. 337-463, on p. 384. (in German)
Klein, Adrian Bernhard (Cornwell-Clyne) (1940): Colour Cinematography. Boston: American Photographic Pub. Co., pp. 150-151.
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 39-40.
Street, Sarah (2012): Colour Films in Britain. The Negotiation of Innovation 1900-55. Basingstoke, Hampshire: Palgrave Macmillan, on p. 39.
“The Morgana Color Process* J. A. Dubray**
The B & H “Morgana” process is an additive color process. Each successive picture frame is analytically photographed through a red and a blue-green filter alternately.
The conventional color filter wheel has been replaced by an oscillating element that brings the proper filter into position between the lens and the film at each exposure. Regular panchromatic reversal film is used.
The normal photo-graphic speed is 24 picture frames per second though other speeds can be used. During projection two successive frames move forward and one backward, or in reverse, in the following order: 1-2; 1-2-3; 2-3-4; 3-4-5; etc.
The result is that, although the film is running at a linear speed of 24 frames (1 2/3 feet) per second, 72 frames are alternating at the aperture during the same length of time, each picture frame being projected three times on the screen.
This accrued projection speed eliminates color flicker and greatly reduces color fringing. A conventional filter wheel rotating before the projection lens at a speed of 2160 r.p.m. synthetically produces the impression of color during projection.
Photographic filters are now available for panchromatic reversal 16-mm film for daylight or tungsten filament incandescent bulbs, selected for proper analysis of color during the photographic process in accordance with the light radiation characteristics of the source of light used.
“Morgana” is the trade-name of an additive 16-mm. color process recently announced by the Bell & Howell Company. Its basic principles are well known,1 and have been applied more or less successfully to the cinematic reproduction of colors practically since the beginning of motion pictures. The process is fundamentally based on analyzing the object photographically into two records of wide and complementary spectral bands. One record (picture frame) selects the so-called “warm” colors, the yellows and the reds; and the other, the “cold” colors, the violet and green.
This selection is obviously attained by using colored screens or filters, which absorb the unwanted colors for each picture frame, and transmit to the film those that are selected. The film must necessarily be sensitive to all the light radiations of the visible spectrum.
The result in the picture print (or film finished by the reversal process) is that the multitude of densities that concur to form the image and that correspond, for each successive picture frame, to the particular radiations transmitted by the selective filters, are inversely proportional to the brilliance of the hues that concur to make the object a colored one. It is quite obvious that the filters will be orange-red for transmitting the “warm” colors, and the complementary blue-green for the “cold” colors.
The fidelity of color reproduction depends mainly upon three factors:
(1) The color-sensitivity characteristic of the photographic emulsion.
(2) The selective characteristic of the photographic and projection filters relative to the character of the source of light.
(5) The instrument (camera and projector) must be so constructed as to fulfill the requisites for analyzing, and subsequently synthesizing, the color radiations of the object.
It is not within the scope of this paper to discuss the first two factors, since many data are already available on these subjects. Suffice it to say, that panchromatic emulsions must, of necessity, be used; and that the filters used for photographing must be so selected as to coordinate the color-sensitivity characteristic of the film with the character of the light used for photographing. Thus, different pairs of filters must be used when photographing with a tungsten filament lamp, and when photographing in daylight. For projection, the color transmission characteristic of the filter is chosen with regard to the light radiated by tungsten filament lamps, which are used exclusively for 16-mm projection.
It may not be amiss to mention here that since the faithfulness with which color is rendered depends upon the above-mentioned physical characteristics, and since these characteristics vary somewhat and are difficult, if not impossible, to control with regard to the visual characteristics of the human eye, the results obtained can only approximate the true colors of the object. The approximation attained, however, is quite close, and, at any rate, very pleasing to the eye.
The designing of the camera for the Morgana process did not present any great difficulties or involve radically distinctive features except as to its portability and compactness.
Fig. 1 shows the external appearance of the Filmo Morgana camera. It will be noticed that the cumbersome filter-carrying wheel usually attached to cameras to be used to take alternate frames through different filters, has been replaced by an oscillating filter carrier (Fig. 2). The red and the blue filters are alternately brought into position between the lens and the film by a to-and-fro motion of the carrier which takes place during the periods of shutter occultation.
The advantages of this method of alternating the filters are: compactness and correspondingly improved portability of the camera; immobility of the filter during the periods of exposure; protection of the filter against possible damage due to external causes; and the facility with which the filters may be removed, permitting the camera to be used for ordinary black-and-white cinematography. Black-and-white pictures may be made with the same roll of film, since panchromatic film is used and the films are processed in the customary way.
The ease with which filters can be withdrawn or inserted in their carrier is illustrated in Fig. 3. By rotating the knurled rim of the camera head, the slot A is brought to the position shown in the illustration and the filter holder is easily withdrawn or inserted, as the case may be. A twist of the knob closes the slot and prevents the filter from moving out of place or stray light from entering the camera when the filter is not in position and the camera is being used for black-and-white work.
Fig. 4 illustrates the inside mechanism of the camera head, which does not differ from that of the similar model of the Filmo camera except for the cam shown at A which controls the oscillating motion of the filter carrier.
Since the sensation of color is attained during projection by the subjective composition of successive complementary frames, it is obvious that each frame should be identical to its complement. This is not the case, however, and the change of position of a moving object, due to the lapse of time between the taking of two successive (complementary) frames, produces the well-known effect called “fringing.” This effect is, fortunately, objectionable only when the object that is photographed is moving rather rapidly across the field of view of the camera and quite close to it.
It is evident that the shorter the time between any two complementary frames the less noticeable will the fringing be. This would naturally suggest that the taking speed be increased. On the other hand, such increase of speed involves an objectionable consumption of film and limitations with regard to the exposure time. It is recommended for satisfactory results that the Morgana camera be operated at a normal speed of 24 frames per second. However, it is not compulsory to maintain this rated speed, but higher or lower speeds can be used to produce slow-motion effects or for photographing inanimate objects. The Morgana camera is therefore equipped with a control by means of which its speed can be varied from 8 to 32 picture frames per second.
No limits are imposed as regards focal length of lenses and diaphragm opening, except for the necessary increase of exposure as compared with black-and-white cinematography, due to the absorption of the filters and the increase of the taking speed. This increase of exposure is, however, relatively small, as it corresponds to a factor of 4x for daylight and of 3x for Mazda illumination.
In the projector (Fig. 5) the conventional color-filter wheel has been retained for convenience of construction as well as for convenience in synchronizing the proper sector of filter with the picture frames corresponding to it.
Fig. 6 is a view of the filter wheel, showing the two color sectors. Each sector is composed of smaller sectors (two for the red and three for the blue) and transparent spacings, the color transmission characteristic and area of each sector being chosen so that the aggregate effect upon rotation will be correct for the color transmission of the taking filter and the color radiation characteristics of the projection lamp.
The most striking feature of the Morgana projector is to be found in the manner in which the motion of the film is controlled at the projector gate.
Since the pictures are taken at a normal speed of 24 frames per second, it would be necessary only to project them at that speed, care being taken that the proper filter is placed before its corresponding frame. However, taking into consideration that the final effect depends upon the ability of the eye to superimpose each pair of complementary pictures, and that the colors of the object are analyzed in terms of only two primary components, it is found that a projection speed of 24 frames per second involves physiological difficulties known as “color flicker” or “color bombardment,” which are extremely disagreeable and fatiguing. It is obvious that the greater the rapidity of alternation of the two complementary colors the less noticeable the flicker will be.
In order to achieve greater projection speed the movement of the Morgana projector is so designed that each forward movement of two successive frames at the projector aperture is followed by a backward or reverse movement of one frame, so that each picture frame is projected three times instead of once. The rate of projection at the aperture is therefore 72 frames per second, although the linear motion of the film at the feed and take-up sprockets correspends to a running speed of only 24 picture frames per second (7.2 inches).
Fig. 7 shows graphically the relation between film movement, time of exposure, and color. The letters R and B indicate the color of the projection filters, red and blue-green, and the arrows indicate the direction of the movement. The graph illustrates the alternation of the red and blue-green filters, and the triple projection of each frame.
The intermittent movement of the Bell & Howell regular Filmo projector is so designed that for every frame “pulled down,” the single-bladed shutter revolves three times. In the Morgana projector, motion is imparted to the film for every revolution of the shutter, the cycle of motion being as stated above, causing a movement of two frames in the forward direction and one in the reverse direction.
Fig. 8 shows details of the Morgana projector gate with the lens and lens holder removed. At A is the pull-down feeding finger. At B is the reverse feeding finger, and at C is a pilot pin that engages the film perforation for each one of its motions, in order to register each frame at the projector aperture.
Fig. 9 illustrates the cams and double shuttle that control the motion of the feeding fingers and pilot pin, again designated by the letters A, B, and C.
The obvious objections to the Morgana process are that it is a two-color process, and that color fringing is experienced in photographing close-ups in fast motion. The Morgana process is practicable despite these objections, because of its manifold advantages.
First, and most important, it allows any lens, from a wide-angle to a telephoto, to be used on the camera; and, perhaps even more important, it allows any number of duplicates to be made, a vital necessity for industrial and educational applications.
Even though it is a two-color process, the only colors that are really lost are the deep purples, the magentas, and the rich yellows. Flesh tones are exceptionally good, much better than heretofore obtained, to our knowledge, with any two-color process.
The backing-up phase of the projection is radically new in projection practice, and is responsible for the ability to show ordinary movement without any apparent trace of flicker or objectionable color fringing, so that for practical purposes, bearing in mind the slight limitations of the process, it is quite satisfactory for industrial and educational applications.
An advantage of the process is the fact that considerably less light is needed for color photography, and that large color pictures can be projected quite readily. With the 400-watt lamp now widely used, an 8 X 10-ft. picture of adequate brilliance for an audience of one to three or four hundred is quite satisfactory. Some interesting work is being done with this new process, including time-lapse work with growing flowers, medical cinematography, and the like.
*Presented at the Spring, 1933, Meeting at New York, N. Y.
**Bell & Howell Co., Chicago, 111.
1Matthews, G. E.: “Processes of Photography in Natural Colors,” J. Soc. Mot.Pict. Eng., XVI (Feb., 1931), No. 2, p. 188. “Photography of Colored Objects,” Eastman Kodak Co., Rochester, N. Y.”
(Dubray, J.A. (1933): The Morgana Process. In: Journal of the Society of Motion Picture Engineers, 21, 5,1933, pp. 403-412.)
“The Morgana Process.
(Owned by The Bell-Howell Co., U.S.A.)
The process is for 16-mm. film. It is an additive process. Each successive picture frame is analytically photographed through a red and a blue-green filter alternately. The conventional colour filter wheel has been replaced by an oscillating element that brings the proper filter into position between the lens and the film at each exposure. (Note the similarity to the oscillating filter in the Hillman camera which was claimed as original.) Normal panchromatic reversal film is used. The speed is 24 frames per second, though other speeds can be used. During projection two successive frames move forward and one backward, or in reverse, in the following order: 1-2; 1-2-3; 2-3-4; 3-4-5; etc. The result is, that although the film is running at a linear speed of 24 frames (1 2/3 ft.) per second, 72 frames are alternating at the aperture during the same length of time, each picture being projected three times upon the screen. This accrued projection speed eliminates colour flicker and greatly reduces colour fringing. A conventional filter wheel rotating before the projection lens at a speed of 2160 r.p.m. synthetically produces the impression of colour during projection.
Dubray, J. A., “The Morgana Process,” Jour. Soc. Mot. Pic. Eng., 21, No. 5, (1933), p. 403.”
(Klein, Adrian Bernhard (Cornwell-Clyne) (1940): Colour Cinematography. Boston: American Photographic Pub. Co., pp. 150-151.)
“Morgana Color Process
The Morgana Color Process was a two-color additive process for 16 mm color cinematography introduced in 1933 by Bell and Howell Company.17 Like the Kodacolor Process it was not intended that this process should be used for entertainment motion pictures. It was introduced as a home movie system for motion pictures with possible application in the field of industrial and medical cinematography.
In a special camera alternate frames were exposed through a red and blue-green filter mounted in an oscillating filter holder. Exposures were made on conventional panchromatic black and white reversal film which was developed normally. Because of the filter factors of the color filters used, an exposure increase of approximately three to four lens stops was required. No limits were imposed on focal length of lenses and diaphragm opening.
After exposure and development the film was projected on a special projector equipped with a color filter wheel. The filter wheel was divided into two color sectors, red and blue; each of these was composed of smaller sectors and transparent spacings. The red sector was divided into two segments, the blue sector was divided into three segments. The color and the area of each sector was chosen so that they would correct for the color transmission of the camera filter and the color characteristics of the projector lamp.
The most unusual feature of the projector was its sequence of projection, two frames forward then one frame backward. The rate of projection at the aperture was therefore 72 frames per second although the linear motion of the film corresponded to a speed of 24 frames per second. Each frame was projected three times. The purpose of this multiple projection of each frame was to eliminate a problem known as “color flicker.”
Some of the advantages of the Morgana Process over other two- and three-color processes were:
1. Conventional film and processing were used.
2. Any focal length or aperture lens could be used.
3. Prints could be made on conventional continuous printing equipment.
4. Less light was required for color photography using this system.
5. Flicker and color fringeing were eliminated.
Some of the disadvantages of the process were:
1. It was a two-color process.
2. Special camera and projection equipment were required.
3. The mechanics of projection was physically hard on the film.
17 Dubray, J. A., “The Morgana Color Process,” Journal of the Society of Motion Picture Engineers, November, 1933, pp. 403-412.”
(Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 39-40.)
“Lediglich in den USA ist um 1930 das “Morgana”-Verfahren, ein Zweifarbenverfahren für die “Filmo”-Schmalfilmkamera der Bell und Howell Co., kurze Zeit im Handel gewesen.31 Bei der Aufnahme wurden durch ein zweiteiliges Filter in den Farben Orange und Blaugrün, das zwischen Objektiv und Bildbühne hin und her geschoben wurde, abwechselnd die beiden Teilbilder erzeugt, und zwar mit einer erhöhten Filmlaufgeschwindigkeit von 24 Bildern in der Sekunde, und einer für Tageslicht etwa vierfach höheren Belichtung. Um das Farbflimmern durch den Filterwechsel bei der Projektion zu verringern, wurde mit 72 Bildern in der Sekunde vorgeführt, dabei jedoch nach Ablauf zweier Bilder um ein Bild zurückgeschaltet, so daß jedes Bild insgesamt dreimal projiziert wird.
31 Dubray: The Morgana Process. J. Soc. Motion Picture Engr. 21, 403 (1933).”
(Heymer, Gerd (1943): Die neuere Entwicklung der Farbphotographie. In: Ergänzungswerk zum Handbuch der wissenschaftlichen und angewandten Photographie. Wien: Julius Springer 1943, pp. 337-463, on p. 384. (in German)
Two-colour additive process
Morganacolor was analogous to a 16mm home movie version of Kinemacolor. In the camera successive frames of the film were exposed through red and blue-green filters. The film was then reversal processed. The projection system was elaborate with each frame being projected three times, twice while running forward and once backwards through a rotating wheel divided into red and blue sectors, which were in turn divided into smaller sectors with transparent spacings. The projection speed was 72fps, but the forwards/backwards motion meant that it corresponded to 24fps and this complex process served to reduce fringing and flicker.
It was based on patents filed by Sydney George Short of London and Lady Juliet Evangeline Williams of Pontyclud. Lady Williams and her husband Sir Rhys Williams set up a small syndicate company in February 1931 with a nominal capital of £100 to take on the rights to the patents and to look into the possibilities of exploiting the system. Both had been involved the previous year with Talkicolor, as had fellow members of the syndicate Elinor Glyn (Lady Williams’s mother) and Lady Margot Davson (Lady Williams’s sister). In May it was agreed that Rhys and Juliet Williams should enter into negotiations with appropriate companies and by the autumn Rhys Williams was in America having talks with Joseph McNabb, President of Bell and Howell in Chicago. An agreement for Bell and Howell to commercially exploit the system was reached in December 1931, at which time the capital of the company was raised from £100 to £5,100. It was agreed that Bell and Howell would pay a royalty fee to the Morgana Syndicate. By April 1932 McNabb had successfully shown the system to the Chicago Cinema Club and was poised for production, but the commercial exploitation was at the mercy of the Great Depression. McNabb requested in May 1932 that the royalty payment be reduced by 50 per cent and by 1933 the whole venture was losing money.
The registrar was informed to dissolve the company in February 1937 and it was noted at this point that the Morgana patents had been allowed to lapse and that the agreement will Bell and Howell was therefore valueless.
BT 31/33242/254470, Morgana Syndicate Ltd, 1931, National Archives.
Cornwell-Clyne, Adrian, Colour Cinematography (London: Chapman & Hall, 3rd edn, 1951), p. 270.
Elinor Glyn Collection, University of Reading Special Collection UoRMS-4059.”
(Brown, Simon (2012): Technical Appendix. In: Sarah Street: Colour Films in Britain. The Negotiation of Innovation 1900-55. Basingstoke, Hampshire: Palgrave Macmillan, pp. 259-287, on p. 277.)
“Talkicolor was also, however, flawed by insurmountable technical problems and Glyn was subsequently involved in an ultimately unsuccessful attempt to exploit a process called Morganacolor […].”
(Street, Sarah (2012): Colour Films in Britain. The Negotiation of Innovation 1900-55. Basingstoke, Hampshire: Palgrave Macmillan, on p. 39.)