US1601616A - Color cinematography, method and apparatus - Google Patents

Description

Patented Sept. 28, 1926.

UNITED v s'raras A y v1,601,616 PATENT OFFICE.

CLAUDE EL FRIESE-GREENE, F BROMLEY, ENGLAND.

COLOR CINEMATOGRAPHY, METHOD AND APPARATUS.

Application led July 16, 1924, SeralNo. 726,398, and in Great Britain May 21, 1924.

This invention relates to color cinematography in which different sections of the surlface of a color sensitive or panchromatic film are exposed alternately to light allowed to pass through filters.

tomary to use a disc havin-g a pair of apertures one of which is filled entirely with a lter'of a particular color, the other aperture only being partially covered, generally l0 a relatively small portion thereof, by a filter having a complementary or differentl color. lt .is known that color sensitive emulsions are more responsive to certain colors' than they are to others, so that itis necessary to determine the transmission of color filters through which the film is exposed, which give the best results. The portions of the spectrum from which these colors are selected are usually from the red side for the wholly covered aperture, and the blue end for the` other filter which generally also passes while light. While this principle gives good results there is'still room for improvement,

particularly in instances where grass and foliege in its natural green state has` to be photographed, also when photographing in a hazy or misty light, the latter condition often existing almost unsuspectedly during very warm and fine weather so that distant definition may be registered; The object of this invention is vto obtain the foregoing d esideratum whereby a more ,perfect reproduch tion of the object photographed is obtained, and in which the fault, commonly known as fringing i's obviated to'a minimum, also re'- duction in speed of projection being obtained together with a finer color gradation. Broadly this invention isy characterized in that the film is exposed through filters all vof which are substantially of the same tone of color, one of thefilters having in conjunction with it an opening passing white light. In the accompanying drawings, whch are illus`- trative of myy invention 1n one preferred form:

Fig. l is an elevation `of a rotatable embodying my invention;

Fig. 2, an elevation of a portion of a film colored'in accordance withmy invention;

and

v Fig'. 3, a view similar to Fig. l showing a slightly modified form f disk.

in the preferredembodment of this invention the col'or employed for the filters is 5% substantially selected from the red side of disk In practice it is custhe density and tone of the two colored filthe' spectrum. Preferably an ordinary rotating disk A is employed, 'rotating at 'haif the speed of an ordinary shutter, but having apertures for filters. -One of these apertures is filled 'entirely with a lter R having 60 la color predominating on the red side of the spectrum. -The -'other aperture is utilized to allow the passage of white light and is partially filled by a filter r with a color also substantially on the red side of the spectrum. The sections of the film B are exposed alternately through the two apertures specified. The results of employing the same color 1n eachl aperture, one of which has an opening allowing the passage of white light gives a result which is appreciably much better than any other arrangement of filters heretofore employed, particularlywith regards to the photography-of ass or foliage 1n its natural green state, tie picture projected from the positive giving a good green reproduction ofthe grass or foliage, as well as finer gradations of other colors with a good distant definition, even when objects at a distance are wrapped in mist.

The area of the color filter employed with the opening passing white light may be varied, also the area of? white light aperture according to the balance required, likewise e5 ters may be varied relatively or in common as desired. The color filter having the .white light opening may include a relatively small proportion of color from the blue part of the spectrum provided that the addition of such blue color will not affect noticeably the predomination of the approximately red color of the filter, should it be considered necessary to assist the color gradations on the blue side. Alternatively a relatively small area of approximately blue filter hav- 'ing the same effect-as the aforementioned incorporation of blue with red may be used in conjunction with the red filter and white aperture as shown by dotted lines at c in Fig. 1 of the drawings. Y

Briefiy it may be stated the preferred embodiment of this invention resides in employing a disk having two apertures employing4 filters substantially red i. e. any 105 J color except that in which the green color related to the red side of the spectrum predominates, for instance orange,v orange red,

and yellow may be employed good examples of suitable dyes being flavajzine T or rose leins, prepared by treating dichlorfluorescein with iodine. l

In employing this invention the best results are obtained by bringing each picture into position for exposure in the gate as quickly as possible, i. e. the rate of change of successive sections to be effected as quickly4 as possible. Also it is distinctly advanta eous to,l carefully balance the luminous values of the colors `applied to the positive film, the colors which are applied to the film being an approximately orange red and an approximately blue green, the former color being applied to those sections of the film which are exposed through the wholly red or approximately-red filter, and the other sections being colored with an approximately blue green in known manner. By means of my 4invention' a much more refined and delicate color gradation is obtained. The quick change feature reduces color fringing to a minimum, and the balance of luminous values reduces flicker andrunning speed during projection. Also owing to the rapid feeding of the film through the gate a longer exposure can be given.

If desired the filter` associated with the aperture passing white light may be split up into a plurality of portons in conjunction with a corresponding splittingup of' the white light aperture as shown at r', lw Z',

respectively, in Fig. 3 of the drawings.

The accoinpanyinfrdrawing, Fig. 1, gives a good example -of the proportions of filters and white opening to give good results under normal fine weather conditions, the white light opening being indicated by the reference W. L. The shaded O part indicates an adjustable opaque filling. The proportions shown inthe drawing have been found to give goods resultsby employing a flavazine T and red benvale filter for the filter R, and a flavazine T filter for the filter r.

The following formulae are suitable for preparing the dyes for the filters and thev coloring for applying to the positive film.

For the lter R':

Base solution No. 1: flavazine T l gram dissolved i-n 2 oz. of distilled water.

Base solution No. 2: rose bengale 1 gram dissolved in 1/2 oz. pure alcohol and add distilled water up to 2 oz.

Method-Immerse a strip of transparent gelatine in base solution 1 for 30 seconds, rinse rapidly in water and allow the gelatine to dry- When dry immerse same in solution' 2 for one minute then han not rinse the solution 2).

up to dry (do gelatine after t e immersion in lll/'then the gelatine is dry cut same .tol fit the aperture in the disk.

To make filter r. Use the same formulae as base solution 1 i-inmersing a strip of transparent gelatine in it for 45 seconds, rinse and allow same to dry. When dry cut to sizey desired.

It is always advisable when filters have been made and set, to'take a test o first so that it is possible to check the balance. A good way of so doing is to photograph objects white and black, the densityvon the resultant negative' of each should appear equal in -each successive picture.

Good formulae for dyeing the positive pictures are as follows:

Orange red for the section that has been exposed throughtlie wholly red filter.

Solution 1: Brilliant red, which is the sodium salt of R-aZo-S toluene p sulplion amino 1 naphthol 3:6 disulphonic acid, .l0A

exposed through the white Iopening and flavazine filter.

Lissamine green, which is sodium salt of tetramethylfdiaminodiphenyl B hydroxynaphthyl-carbinol disulphonic acid anhydride, 10 grams.

Disulphine blue, which is calcium salt of the disulphonic acid of m hydroxy dibenzyldiethyldiamino-triphenylcarbinol anhydride, 5 grams.

Mix with little distilled water into a thin paste then add distilled water up to 35 oz.

I claim: I l

1. The method of producing color cinematograph pictures which consists in alternately exposing different sections of a sensitized film through a plurality of filters all of which are of substantially the same tone 0f color on the red side of the spectrum and one of which has associated with it an opening passing white light.

2. The method of producing a color cinematograph film which consists in exposing Mmmm ' Y altarnatsly substantially' @1m-ng@ 'ated and -bue green, thev blue" green, coloring heingingpsingwhiie light c. In c0101' mammography appnmtus 'a l arrangd'theren in spaced vlatelation Awhre'by LAUEL @IESE-GREENE.

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