US1864445A - Stereoscopic cinematography - Google Patents

Description

June 21, 1932. E, P, 1 LE BARBIER STEREOSCOPIC CINEMATOGRAPHY Filed Feb. 5, 192'9 3 Sheets-Sheet 2 June 21, .1932.4 E. P. l.. LE BARBIER STEREOSCOPI GINEMATOGBAPHY Filed Feb. 5, 1929 3 Sheets-Sheet 3 Patented June 21, 1932.l

PATENT OFFICE SMILE PIERRE LOUI LE BARBIER, F NICE, FRANCE y srnmzoscorxc cnn::nm'roaanrrrry Application led February `li., 1929, Serial No. 837,687, and in Belgium March 30, 1928.

The present invention relates to stereosc opc photography and, more particularly, to the application of the stereoscopic priuciple to the production of moving pictures.A f One ofthe objects of the invention is to y provide a method and apparatus for produclng enlar ed stereoscopic images ofv objects correspon ing substantially to those observed by the human eye. Another object is to provide means for registering right and left stereoscopic images on the same stri of film.

Further o jects will appear in the course ofthe detailed description now tov be given with nreference to the accompanying drawings, in which ig. 1 is a diagram showing the relative positions of the object and one form of aparatus constructed in accordance with the invention;

Fig. 2 is a similar diagram showing the positions that would be occupied by the same object relatively to the ordinary types of stereocinematographic apparatus now in 85 use;

Fig. 3 is a diagram showing the position which the object occupies relatively to a second constructive embodiment of theinvenj tion;

3 0 Fig. 4 is a diagramlshowing the position that the object represented in Fig. 3 would occupy relatively to an ordinary stereocinematographic apparatus; A

Fig. 5 is a plan of an apparatus embodying theprinciple of the devices illustrated diagrammatically in Figs'. 1 and'3;

` Fig. 6 represents, in elevation, the position of lhe lm relatively tothe apparatus shown in i 5; Figgs. 7 and '8 are elevations and plans, respectively of the apparatus illustrated in Fig. 5,- showing all the essential constructive details thereof. In the stereoscopic systems employed up to maintain the two objectives used for taking -.the picture and for projecting at a fixed distance corresponding approximately vto thatl of thehuman eyes i. e. 60-70 millimeters,

generally in the vicinity of 63 millimeters.

the present time, it .has been the custom to This procedure is perfectly logical when the negatives are viewed in the ordinary stereoscope, but has serious defects-where the image being projected is considerably magnified as in stereocinematography. In order that the impression of relief be the same for the spectator in the Acase of a magnified image as is observed by a pair of normal eyes, it is necessary that the distance between the objectives be increased in proportion to theirelative size a0 of the real object and the image as received on the screen. In cinematography, for example, it is common to enlarge the object in the proportion of `1 2 or 1 3. The distance between the objectives should, therefore, be 55 twice or three times -70 mm. If the degree of enlargement of the object be represented by n, the distance between*` objectives may be taken as n X 60-70 mm3. The angle of convergence of the eyes may be taken'as a 70 measure of the relief obtained. If, therefore, it be desired to conserve the same relief in an enlarged image, it is necessary to maintain the same angle of convergence during projection.

When enlarged projections are made with. objectives 60-70 mm. apart, blurring effects are obtained because of the impossibility of -superposing the edges of each object in the field. With the objectives in the position above defined this effect is, as will be shown later, done away with.

Figs. 1 and 2 show, diagrammatically, the

differences in relief obtained withl the type of stereoscopic apparatus now. generally in g5 juse and with an apparatus of the type hereinafter to be described, In both figures the cylinder is assumed to be viewed laterally by two normal eyes (or objectives) at o and, o1'

ls ituated on line AB. When projected at double enlargement, the cylinder axis C will -rem'ain the same but its radius will be2 r and thedistance between axis C and line AB will be doubled i.- e. at DE. A

In Fig. 1, the objectives, situated at O and vOx 'on line DE are spaced at double the discylinder of radius 2 'r will, therefore, have the same aspect and present the same relief as the original cylinder and angle will be equal to angle In the case represented in Fig. 2, the eyes (or objectives) are at o, o1 but they are spaced at the same distance at O, O1. An le a viewed from O, O1 will be greatly re uced and the magnified image of the cylinder will' lack the relief of the original. Angle embraces a larger sector i. e. is increased by twice the angle y, while the oblique portion whose relief is to be reproduced is reduced to 2 8.

The increase of distance between the objectives involves certain chan es in the medium, and back grounds, the luminous rays, in certain cases, crossing behind, or to the left or right, of those of the foreground. In this connection it is to be noted that:

1 the visual sensation of relief exists readily only for objects in the foreground, and objects in the medium or back ground are estimated by comparison with those in the foreground;V

2 normal eyes do not perceive accurately horizontal errors in the spacing of objects the maximum angle of displacement of the eyes in their orbits being about 85, if the spectator is close to a screen, he will see accurately only a limited portion thereof, and errors occurring in distant portions will escape him entirely, while, if placed ata disv tance from the same screen, he will view the entire image but will not detect errors in projection because'of therelatively large space intervening between himself and the screen;

3 normal eyes are much more sensitive to yerttsical errors in the representation of obleC From the foregoing it follows that, while the distance between a pair of objectives may be increased safely in horizontal directions up to ab0ut85 in conjugated and convergent types of apparatus, the vertical dist ance therebetween should not be altered.

Fig. 4represents,diagrammaticall a stereocinematographic apparatus of t e type` `now in use. o and o1 are objectives having parallel axes a: y and ai y', and F, F1 a pair of films positioned perpendicularly to the latter. A c linder having an axis C isrepresented as eing viewed laterally by the objectives. Each image of the cylinder hasl the form of a non-symmetrical deformed oval shown in solid lines on the film which is supposed to be turned into view. In lreality this image is formed between two circumferences shown. in dotted lines. The deformation is diicult to detect in ordinary stereophotography because of the fact that the composite image resulting from the superposition of points f and f1 is much smaller than the object photographed. In stereocineniatograf phy, when the proj ected image is considerably larger than the original object, this defect becomes at once apparent and requires correction.

Fig. 3 shows how correction is obtained. Here, the axes of ob'ectives o and o1 are convergent and films F1 are positioned perpendicularly to said axes. The images reproduce exactly the real shape of the object ,and 'the deformation noted above is done away with. The constructive embodiment of the invention shown in Figs. 5 to 8 consists of a positioned to receive rays from g, ggf-and a film receiving simultaneously a pair of juxtaposed images 7', j.

Simultaneous control of arms g, g yand of 'mirrors g2, g2 is obtained by means, of a milled disc .(not shown) capable of being manipulated by hand'to rotate a gear m, the latter driving (l) arms g, g simultaneously in opposite directions through the intermediary of pinoins n, fn, and worms n', 'n2 mountedon shafts nl, n1, and independent sectors g, ga connected in driving relation to g, g, and (2) mirror g, g2 through the intermediary of pinions n, n, helicoidal gear q1 mounted on shaft g, a pair of gears similar to Y inions n, n driven from shaft q and driving worms p, p, and concentric gears g, g* attached to each mirror mounted on concentric shafts g, g.

` The various gear systems should be designed so that (1) arms i, g' are displaced simultaneously through t e same angle, and (2) mirrors g2, g through an angle equal to one-half of thatof each arm.

In proceeding to effect a photographing.

operation, (1) the right hand objective may be focussed on the center of the sub'ect, and the left hand image on the ed of e latter 'or conversely, or (2) a combination of these procedures may be employed so as to accentuate one image or the other. To insure accurate superposition in projection, the first images may consist sim y of reference marks i. e. of central vertical or horizontal lines which may be centered in the manner generally employed in polychrome photog raphy.

What I claim is 1. In combination, a pair of extensible arms rotatable about a common axis, said arms being rotatable indifferent planes, re-

.ilecting elements supported on said arms, a

lens system, and means for reflecting images Projected by thereflecting elements into'said ens s stem. 2. n combination, a pairy of extensible arms rotatable about a common axis', said 6 arms being rotatable in different planes, re-

fleeting elements mounted on said arms, a lens s stem, means for reflecting images projecte by said reflecting elements into saidl lens system, and means for simultaneously 10 displacing said arms through equal angles.

3. In combination, a pair of extensible arms rotatable about a common axis, said arms being rotatable in diierent lanes, refleeting elements supported by said arms, a .15 lens system, reflecting means interposed between said relecting elements vand the lens system and adapted to deflect light rays coming from the former into the latter, and-means 4for simultaneously effecting angular dis-vv 20 placement of said reflecting means and of said arms. p

4. The method of producing stereoscopicl images which comprises the step of increasing the distance between a pair` of objectives 25 during photographic registration beyond 70v millimeters by an amount pro ortional between the size of the object in photographed and the size ofthe'image t ereof as projected on a screen. 80- I n" testimony whereof I have signed this specification.

EMILE PIERRE LOUIS .LE BARBIER.

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