US2001256A - Method and apparatus for obtaining stereoscopic effects - Google Patents

Description

May 14, 1935. E. P. LE BARBIER 2,001,256

METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original Filed May 1, 1931 3 Sheets-Sheet l May 14, 1935. E. P. L. LE BARBIER METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original Filed May 1, 1951 3 Sheets-Sheet 2 May 14, 1935. p, LE BARBER 2,001,256

METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Original Filed May 1. 1931 3 Sheets-Sheet 3 fmi/e firm: 140/3 e g f/e 7 mm M.

UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR OBTAINING STEREOSCOPIC EFFECTS Emile Pierre Louls Le BarblerQNioe, France Application May 1, 1931, Serial N0. 534,179. Be-

newed February 26, 1935.

3 Claims.

The present invention relates to methods in apparatus for obtaining stereoscopic effects in a single positive or negative.

It is well known that stereoscopic elfects may 5 be obtained by simultaneously photographing a single object from two different angles optically combining the two images thus produced. It is not so commonly known that the human iris normally varies very rapidly in diameter and gives the sensation of depth due to these variations. As tending to prove the latter, it is to be noted, that when atropine or any similar drug capable of paralyzing the iris is injected into the human eye, variations in diameter of the pupil are done away with and the possibility of judging depth is simultaneously lost.

One of the objects of the present invention is to produce photographs and, more particularly, cinematography positives and negatives which each, taken alone, give the sensation of depth without combining a second image therewith in any way, relief being obtained by varying the effective aperture of the objective during exposure (or projection).

Other objects will appear in the course of the detailed description now to be given with reference to the accompanying drawings, in which:

Figs. 1 to 7 are seven diagrams illustrating the principle upon which the invention is based;

Fig. 8 shows one constructive embodiment of the invention;

Fig. 9 illustrates a second form of the invention;

Figs. 10 to 12 inclusive show various forms of the invention adapted to produce effects of the type illustrated in Figs. 1 to 7.

The human iris has a double function (1) to limit the amount of light entering the eye and (2) to produce a sensation of relief, this latter effect being produced by rapid variation of its diameter within certain limits. In the structures forming the subject matter of the present invention these functions are divided between two diaphragms, one serving, as in ordinary cameras, to limit the amount of light traversing the objective and the other to vary the section of the light beam passing through the latter during the period of exposure.

The rate of variation of the section of the light beam traversing the objective may be adjusted to have any one of the forms shown in Figs. 1 to 6, i. e., it may decrease from the maximum aperture D determined by the fixed diaphragm toward a minimum at the end of time T (Fig. 1), or increase from a minimum to maximum aperture In Belgium May 6;

D in time interval T (Fig. 2), or first increase and then decrease (Fig. 3) or decrease and then increase iFig. 4), or again exhibit various combinations of those described as shown in Figs. 5 and 6. 5

Whatever be the rate of variation of the section of the light beam traversing the objective and falling upon the sensitive emulsion, either one of the assemblies shown in Figs. 8 and 9 may be used to produce the effect desired.

In the form of structure represented in Fig. 8, and objective 0 is fitted with a fixed" diaphragm of the usual form (not shown) and is mounted so that an arcuate slot 3 in a rotatable shutter 9 moves thereacross so as to diminish the section 15 of the light beam passing therethrough from a maximum value D to any minimum desired in a time interval T. The axis of slot 3 should be positioned to move symmetrically with relation to the optic axis of the objective and will produce 20 variations in the section of the light beam represented by the diagrams in Figs. 7 and 8. In the diagram shown in Fig. 7, the numerals I, 2, and 3 show how the variations in section would be distributed for successive images in a cinemato- 25 graphic apparatus where T represents the exposure period and T the nonexposure interval between successive photographs. For the diagram shown in Fig. 8, T and T have the same significanoe, while t represents the angle through which 30 the shutter turns during one half of its course and before the forward edge of slot 3 moves into alignment with the objective.

In the form of structure shown in Fig. 9, the shutter is provided with a slot of constant width 35 and variations in the section of the light beam traversing the objective are obtained by rapidly varying the opening of a diaphragm in timed relation to the movement of the shutter, the maximum amount of light capable of traversing the objective being limited by a second fixed diaphragm (not shown). Here shutter 9 is provided with a slot 3 of constant width positioned to move across the optic axis of objective 0, the effective section of the light beam trav- 45 ersing the latter being varied by a diaphragm 2 whose aperture is changed in timed relation to the rotation of disc 9 by the action of a cam I reacting on a lever and link system 5, I to displace a finger 6 acting directly on the diaphragm. 50 The relative timing of the shutter and diaphragm may be varied by shifting the position of pivoted extremity 8 of element 5 in a. manner which will at once be obvious to those skilled in the art. The extreme positions of the lever and link system are represented by 5, 6, l and 5 6 and I In this form of structure, disc 9 may be completely eliminated if the variations in the aperture of diaphragm 2 are made sufilciently great to provide for a period of complete closure during displacement of the film the diameter of said aperture being varied only during the period of exposure.

In the form of apparatus shown in Fig. 8, which may serve either as a photographing or projecting unit, slot 3 may be given any one of the forms shown in Figs. 10 to 12. If slots of the type of H, i l shown in Fig. 10 be used, variations in aperture will take the form shown in Figs. 1 and 7. If, contrariwise, the slots be given the form and orientation shown in Fig. 11, the variation of aperture will follow the diagram shown in Fig. 2 when disc 9 turns in the directions of the arrow. Finally, if the slots be given some such form as is shown in Fig. 12, any one of the forms of variation in aperture shown in Figs. 3 to 6 may be produced.

In the case of the structure shown in Fig. 9, the form of variation of the aperture curve may be varied by changing the shape of cam 4 or the position of pivot 8 along a graduated scale.

While the hereinabove described structures may be used for either photographing cinematographically (or otherwise) or for projecting, it is found that the best eiTects are obtained by combining inverse efiects during the taking of the photograph and its subsequent projection. For example, a film may be exposed with the form of shutter shown in Fig. 10 and projected with one of the form represented in Fig. 11, the integration of effects thus obtained (corresponding to a summary of the variations in Figs. 1 and 2) yielding a total effect corresponding to that of a shutter of constant width or aperture (the summary of Figs. 1 and 2 yields a substantially rectangular diagram).

In setting up the apparatus, the distance between the objective and the film or plate is adjustedsoastoobtainasharpimage intheioreground, the various planes toward the background coming automatically into focus as the aperture varies. Contrariwise, it desired, the distance between the objective and the emulsion may be set for the background, variations in the aperture being designed to bring the foreground gradually into focus.

The invention is, obviously, not limited to rotatable shutters but may be applied to focal plane, oscillating and other types.

What I claim is:-

1. The method of producing monocular images in relief comprising the steps of providing an objective and a light sensitive material, varying the efiective aperture of said objective during the period that light is passing therethrough onto the light sensitive material, and projecting a beam of light through the image so obtained while varying the effective aperture of the projecting light beam during projection.

2. The method of producing monocular images in relief comprising the steps of providing an objective and a light sensitive material varying the effective aperture of said objective during the period that light is passing therethrough onto a light sensitive material, and projecting a beam of light through the image so obtained while varying the effective aperture of the projecting light beam during projection at an inverse rate to that employed during exposure of the light sensitive material.

3. An apparatus of the class described comprising an objective, and a movable shutter, said shutter having a pair of coaxial slots formed therein positioned to move across said objective, one of said slots presenting portions oi. increasing section when said shutter is displaced in a predetermined direction, the other slot presenting portions of diminishing section when said shutter is displaced in the same direction.

EMILE PIERRE LOUIS LE BARBIER.

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