WO1989006827A1

WO1989006827A1 - Photographic camera

Info

Publication number: WO1989006827A1
Application number: PCT/GB1989/000054
Authority: WO
Inventors: William Ling
Original assignee: Aspex Limited
Priority date: 1988-01-19
Filing date: 1989-01-19
Publication date: 1989-07-27
Also published as: GB8801077D0

Abstract

A photographic stills camera provided with a mechanism, coupled to or forming part of the camera shutter, for modifying the light falling from a scene on to film in the camera during exposure of the film, so that during the exposure a number of successive images of the scene, or of parts of the scene, are recorded on the film in light of different colours. In one form, the mechanism comprises a series of filters, with a drive mechanism for moving the filters across the optical path of the camera during exposure of the film. The series of filters may be formed on a filter member consisting of two or more portions of different colours, for example two portions of complementary colours such as red and cyan or three colours such as red, blue and green, arranged to be moved so that each frame of the film is exposed successively in the different colours as the filter member moves across the optical path. Alternatively the filter member may be arranged so that each successive image is divided into a number of areas which are recorded in light of different colours, each area being itself recorded in different colours in the successive images. Any movement in the scene being photographed causes the images or partial images in different colours to be displaced relative to one another on the film. When the developed photograph is viewed through appropriately coloured filter spectacles, a stereoscopic effect is obtained. In another form of the invention, a mechanism is provided for altering the path of light through the optical path of the camera during exposure, for example by moving the lens or the film holder, to ensure that the different colour images are displaced, even when there is no movement in the scene.

Description

PHOTOGRAPHIC CAMERA

This invention relates to photographic cameras.

More particularly, the invention relates to photographic stills cameras for taking photographs which give a stereoscopic effect.

Stereoscopic cameras are known. They usually consist of cameras having two lenses spaced apart horizontally to produce anaglyphic pairs of images, or cameras having specially formed lenses designed to produce autostereoscopic images.

These known forms of camera have the disadvantage of being complex and expensive to manufacture.

Stereoscopic vision relies on the fact that each eye sees a different aspect of the same object. This stems not only from the different positions occupied by the two eyes, but from the fact that there is usually movement in the scene being viewed, or movement of the eyes themselves. A person's head is for a large part of the time in constant movement, as are the eyes within the head, as they constantly scan the scene they are looking at. This causes continuous change in the aspects of the scene being viewed by each eye, which is important in the perception by the brain of the "dimensionality" of objects in the scene. Any movement in the scene, even of a single moving object, will increase the stereoscopic effect, even if the eyes are kept stationary. The present invention makes use of this effect in producing stereoscopic images, in contrast to the known techniques, which usually rely on the formation of separate images through separate lens systems or specially formed lenses.

This invention consists in a photographic camera provided with means coupled to the camera shutter for modifying the light falling from a scene onto film in the camera during exposure of the film, so that during the exposure a number of successive images of the scene, or of parts of the scene, are recorded on the film in light of different characteristics.

The characteristics of the light are such as to enable the overlaid images to be distinguished when the images are subsequently reproduced in the finished photograph or slide. In the preferred form of the invention, the successive images are recorded in light of different colours, preferably in two complementary colours, such as red and cyan. However, it may be possible to record the images in light of different planes of polarisation, provided that the photographic film is capable of recording the polarisation of light forming the image.

To enable the images on the finished photograph to be viewed stereoscopically, they may be viewed through a pair of spectacles, each lens of which comprises a filter allowing transmission of light such that the right and left eyes of the viewer see different ones of the successive images or differrent combinations of the images. For example, if successive images in two colours are employed, each lens may allow transmission of light corresponding to one of the two colours. Alternatively, if the images are formed by the use of polarising instead of colour filters, the result can be viewed through spectacles containing cross-polarising lenses. The use of complementary colours or polarisation enables full-colour stereoscopic images to be produced.

By coupling the light-modifying means to the camera shutter, so that the time intervals between the successive images will relate to the shutter speed, it is possible for the camera to make photographs which, when viewed without spectacles do not appear as degraded or double images but as acceptable full-colour images, giving the viewer the option of looking at the photographs "normally" or, with spectacles to give a stereoscopic effect.

It has been proposed, in an article by R S Harris published by Eastman Kodak in the "Kodak Workshop Series", publication No. KW13, to construct a shutter arrangement for a still camera which enables the film to be exposed sequentially to red, green and blue light. If there is movement in the scene being photographed, this will give rise to streaks and swirls of colour around moving objects in the photograph, to add a sense of movement or give an interesting visual effect. However, Harris does not suggest that this principle can be used to give photographs with a stereoscopic effect. There is no suggestion that the Harris shutter arrangement can be coupled to the camera shutter.

In a camera in accordance with this invention the means for modifying the light falling onto the film may comprise a series of filters movable across the optical path of the camera. The filters may for example be mounted on a filter member movable horizontally in a straight line, or on a rotatable filter member.

The filter member may take various forms. In its simplest form, the filter member may consist of two portions of complementary colours, such as red and cyan, arranged so that each frame of the film is exposed successively in the two colours as the filter member moves across the optical path. For example, as shown in Figure 1, a horizontally movable filter member 10 may consist of two equal portions 12 and 14 of red and cyan. Figure 2 shows an equivalent rotatable member 16, having two equal angular segments 22 and 24 of red and cyan. The filter members could be divided into more than two portions, for example into four portions arranged in the sequence red-cyan-red-cyan.

Instead of two colours, the filter member could be divided into three colours, such as red, blue and green, which could be arranged in various different sequences.

In use of such filter members, successive single colour images, for example in red and cyan, are overlaid in the finished photograph. Stereoscopic information about objects in the scene which move between recording of the successive images is effectively encoded in the disparity between the single colour images superimposed in the photograph. However, this information will be different depending on the direction of movement of an object across the scene. For example, suppose an object is moving from left to right across the scene, and that two successive images are recorded on the photograph, first through a red, then through a cyan filter. From the point of view of the camera, the red image will correspond to the image of the object as seen from a point slightly to the right, as compared with the cyan image, the degree of misalignment or disparity depending on factors such as the speed of movement of the object and its distance from the camera. If the superimposed images are viewed through spectacles so that the red image is presented to the right eye and the cyan image to the left eye of the viewer, then the crossed horizontal disparity between the images will be equivalent to that caused by viewing an object suspended in front of the photograph, simultaneously from points spaced to the right and left of a central position, as in normal binocular vision. If one now considers an object moving from right to left across the scene, the right and left eyes will again be presented with different images, but they will now correspond to the uncrossed disparate images of an object behind the photograph. Since this is an improbable stimulus in normal binocular vision, information provided by the two images, it would be expected that no stereoscopic effect, or an incorrect stereoscopic effect, would be observed. Similarly, an object moving vertically in the scene would give rise to vertically disparate images, which would not be expected to give rise to a stereoscopic effect. If the camera undergoes translatory motion while viewing a three-dimensional scene, all objects in the scene, except those at optical infinity, will give rise to disparate images on each frame, the disparity varying appropriately with the distance of the object from the camera. Camera motion in one direction (right to left in the system described above) will generate disparities of correct sign, which would give rise to a strong stereoscopic sensation for the entire scene when the photograph is subsequently viewed. Camera motion in the opposite direction will reverse the sign of all disparities, which might be expected to produce a reversed stereoscopic sensation.

In practice, it is found that reversed stereopsis rarely if ever occurs and the stereoscopic sensation is appropriate in direction whatever the motion of object or camera. It appears that the strong monocular cues (e.g. linear perspective, relative size, motion parallax) determine the depth impression of the picture and any horizontal disparities in the image can enhance but not override the depth sensation.

Use may be made of this effect by arranging the filters in the filter member so that opposite sequences of colours occur as the filter member moves across the optical path, for example by arranging the filters in a sequence such as red-cyan-cyan-red.

Alternatively, in accordance with a preferred feature of this invention, the filter member can be arranged so that each successive image is divided into a number of areas which are recorded in light of different colours, each "area in the successive images being recorded in different colours.

Figure 3 shows an example of such a filter member 30, in which the filter is divided into a number of horizontal bands. Each band consists of equal red and cyan portions, the sequence of red and cyan alternating. from band to band. Figure 4 shows an equivalent rotatable filter 56, which is positioned relative to the film frame 50 so that the banded filter portion 52 moves past the film frame in a manner similar to the horizontal movement of the filter member of Figure 3.

The filter member may be located anywhere in the optical path of the camera: in front of or behind the lens, or between the elements of the lens, or at the focal plane. The filters may take any suitable form, for example dyed-in-the-mass or dichroically coated transmission filters, or combinations of polarising and birefringent material. The boundaries between different colour filters need not be sharp, and in some cases continuous spectrum filters may be used. Cross-polarising filters may be used in conjunction with a photographic film able to record the plane of polarisation of the incident light.

In one embodiment of the invention, a filter member such as that shown in Figure 3 having two opaque portions 38 extending from each edge of the filter portion 32, is mounted so as to be movable horizontally across the optical path of the camera in the manner of a guillotine shutter. The filter member may be driven mechanically, by suitable connection to the shutter mechanism of the camera or electro-mechanically, power being derived from a battery included in the housing of the camera. The filter member may work in conjunction with a conventional shutter mechanism of the camera, for example a mid-lens bladed diaphragm shutter, or a focal plane shutter of a laminar or dual curtain type, the driving mechanism of the filter member being suitably coupled to the shutter mechanism so that the filter member moves to sequentially expose the film to the alternating bands of filters whilst the camera shutter is open to expose the film. In single lens reflex cameras, the filter mechanism, may be connected to the reflex mirror mechanism.

Alternatively, the filter member could also act as the camera shutter, avoiding the need for a separate shutter mechanism. The filter member may be mounted in any suitable position, for example behind the lens, between the lens elements or even in front of the lens.

In another embodiment of the invention, a rotatable filter disc, such as that shown in Figure 4, is mounted at a suitable point in the optical path of the camera, driven to rotate in synchronism with the camera shutter. The disc shown in Figure 4 has a filter portion 52 consisting of part-annular bands of two colours, corresponding to the bands of the filter of Figure 3. The portion of the disc not occupied by the filters 52 is occupied by an opaque sector 46. This opaque sector obstructs the film frame before and after exposure, as the disc rotates through 360º for each exposure. The disc can therefore be used as the camera shutter, or alternatively in conjunction with a conventional shutter. For example, the filter disc may be mounted at the focal plane of the camera, for example in a single lens reflex camera, where the disc could be used in conjunction with the reflex mirror and/or a mid-lens diaphragm shutter.

Alternatively, in a single lens reflex camera, the disc shutter may be set to rotate at 45º to the optical axes of the lens, and the opaque sector 46 mirrored, so that the disc can act as the reflex mirror for the viewfinder.

In a camera of the compact viewfinder type, the disc shutter could be mounted behind the lens, or between the elements of the lens, acting in conjunction with a conventional shutter mechanism, or itself taking the place of the normal camera shutter.

Figure 5 shows an alternative form of disc shutter, in which the portion of the disc not occupied by the filters is left open, or is transparent. Such a disc may be mounted at the focal plane of the camera, or in another suitable position in the optical axis of the camera, the disc shutter being operated in conjunction with a conventional camera shutter. Various other combinations of colours, and configurations of the areas of different colour could be used. For example, the bands of colour in the filter of Figure 3 could extend at an inclination to the horizontal or, in the filter disc of Figure 4, spirally. More than two colours could be used.

Instead of using a filter member such as that of Figure 3 in the manner of a guillotine type shutter, the filters could be incorporated into a filter member constructed in the same way as a dual curtain type focal plane shutter, or a laminar type shutter. Such a filter member could be mounted in the focal plane of the camera, and could either take the place of the conventional camera shutter, or be used in conjunction with conventional shutter mechanism.

Since it is possible to construct the filter member so that it operates in a similar manner to a conventional shutter, of any of the various types referred to above, and may in some cases act also as the camera shutter, a camera in accordance with this invention may be made by a relatively simple modification of an existing camera, by suitably modifying the existing shutter of the camera.

In accordance with a further aspect of this invention, the means for modifying the light falling on to film in the camera during exposure of the film is provided in a separate device adapted to be connected to an existing camera, so enabling the camera to be used both as a conventional camera and as a stereoscopic camera.

In one form of the invention, a filter member, either of the horizontally movable kind as shown in Figure 3 or a rotating member as shown in Figure 4 or Figure 5, is mounted, together with a suitable driving mechanism, in a housing adapted to be fitted to the front of the camera lens. For example, the housing may be arranged to be fitted by means of standard adaptor rings. The movement of the filter member may be effected mechanically, for example by a spring shutter device, or electromechanically by means of a suitable drive in the housing. The power for the drive may be from a battery mounted within the housing, or by a suitable connection to batteries in the camera.

Since most movement in a scene is horizontal, the shutter member will operate effectively only when the filters move generally horizontally across the film frame. To enable the camera to be used din a vertical format, ie. with the camera moved through 90º, the housing for the filter member may be adapted so that it can be rotated through 90º relative to the camera body, to retain the horizontal movement of the filter member.

In another embodiment of the invention, for use with cameras having inter-changeable lenses, the housing for the filter member is adapted to be fitted between the lens and the body of the camera. The housing may be arranged to be fitted to the camera and the lens in the same way as conventional adaptor rings, of the kind used to alter the focal length of the lens. Mechanical and electrical connections, of the kind used in conventional adaptor rings to connect the mechanism of the camera body to the lens, may be used to couple the drive for the filter device to the camera mechanism.

An advantage of positioning the filter member between the camera body and the lens is that the filter member can be smaller in size, since light entering the camera has been converged at points behind the lens. Since inserting the device between the camera and the lens will alter the focal length of the lens, it may be necessary to insert a corrective lens or lenses into the device.

Figures 6 to 8 illustrate embodiments of this invention which make use of the fact that light can be filtered by passing it through three elements, consisting of a first linear polarising medium, a bi-refringent medium, and a second plane polarising medium. The first polariser allows only light with one plane of polarisation to pass. The bi-refringent medium rotates the plane of polarisation of the light through an angle which depends on the wavelength of the light. The second polarising medium will therefore allow light of only a narrow wave band to pass, the colour of the transmitted light being dependent on the relative angles of orientation of the three elements.

Thus, in accordance with a further aspect of this invention, the means for modifying the light falling onto the shutter comprises a first polarising element, a birefringent element and a second polarising element arranged in the optical path of the camera, and means for altering the relative orientation of the elements thereby to modify the light falling onto the film during exposure of the film.

For example, two of the elements could be fixed in position, whilst the other element is rotatable through an appropriate angle. By rotating one of the elements through 90º during an exposure, the colour of light passing through the three elements will change, e.g. from red to blue, or vice versa, through the spectrum.

Figure 6 illustrates diagrammatically a possible arrangement, having a fixed polarising element 50, a fixed birefringent element 52, and a rotatable polarising element 54, arranged in the optical path of the camera. Element 54 is rotatable by a drive mechanism 56. The drive mechanism could be purely mechanical, for example a spring motor linked to the camera shutter, or could be electromechanical, for example an electric motor. The electric motor could be coupled, for example, to the camera flash synchronisation, and could be made to operate at variable speed, suitable control circuits being provided.

The elements could be installed at any suitable point in the optical path of the camera, or could be mounted in a separate unit for attachment to an existing camera. Figure 7 illustrates one such unit, having a casing 60 adapted to be fitted to the front of a camera lens. The rear part 62 of the casing houses the fixed polarising element and birefringent element and the drive mechanism 56, whilst the. front part 64 houses the rotatable polarising element. If the drive mechanism is mechanical, it may be operated e.g. by a double cable release 66 or electronic release, connected to the unit and to the camera shutter mechanism.

Alternatively, the unit could be adapted to be fitted between the camera lens and the camera body.

Instead of rotating one of the elements of the polariser-birefringent-polariser combination, one of the polarising elements could be replaced with a liquid crystal polariser of the kind in which the orientation of the plane of polarisation of light transmitted through the crystal can be altered by altering the direction of an electric field applied across the crystal. For example, the crystal could be provided with two sets of electrodes arranged at 90º, alternately energised by a suitable switching circuit. The circuit could be designed to operate so that a voltage was applied to one pair of electrodes for half the exposure time, and to the other pair for the remainder of the exposure. The circuit could be powered by its battery, or by a battery in the camera. The circuit could be coupled to the camera flash synchronisation circuit to initiate its operation. The timing of the circuit operation could be preset by a manual control, or could be linked to the camera shutter controls so that the timing was automatically changed if the shutter speed was changed.

These embodiments of the invention could be modified to enable stereoscopic information appropriate to both directions of horizontal movement in the scene to be recorded on the same photograph. For example, in the embodiment employing a switched liquid crystal polariser, the switching could be arranged so that the film was exposed in a sequence such as red-cyan-cyan-red, by switching the direction of the applied voltage after one quarter of the exposure period and again after three quarters of the exposure period. Alternatively, one of the fixed elements of the polariser-birefringent-polariser combination formed with areas of different orientation, for example to produce an effect similar to that of the banded filter shown in Figure 3. For example, the birefringent element could be formed, as shown in Figure 8, with bands 80 and 82 oriented alternately at 90º to one another, so that the film would be exposed in bands of two different colours, the colour of each band changing from the first half to the second half of the exposure.

In operation of a camera according to this invention, it is necessary for the camera shutter to be fully open whilst the successive exposures in light of different colours are made. This may set an upper limit to the shutter speed which can be used. Because of this, there may be an advantage in linking the operation of the filter means to the flash synchronisation controls of the camera, since such controls usually themselves impose a limitation on the shutter speeds which can be used.

As mentioned above where successive images on the film are recorded in light of different colours, the choice and sequence of colours could take many different forms. Part of the exposure could be made in "white" light, for example by including in the sequence of filters used in embodiments such as those of Figures 1 to 5, a filter transparent to white light. This could be useful, for example, in reducing the intensity of the "fringes" at the edges of moving objects, to increase the acceptability of the photograph when viewed without spectacles.

The preparation of the exposure taken in white light could be selected to give an acceptable image viewed without spectacles whilst giving a stereoscopic effect when viewed with spectacles.

Since the stereoscopic effect provided by the camera of this invention depends on some movement in the scene being photographed or some relative movement between the scene and the camera, the cameras described above will not produce a stereoscopic effect when photographing a completely still scene, unless the camera is moved during the exposure.

In accordance with a further aspect of the present invention, there is provided a photographic camera having means for modifying the light falling onto film in the camera during exposure of the film, so that during the exposure a number of successive images of the scene, or of parts of the scene, are recorded on the film in light of different characteristics, and means for altering the path of light through the optical path of the camera to displace the successive images relative to one another.

Alteration of the path of light to displace successive images can be achieved by moving one or more elements of the camera during the exposure.

Preferably, the movement, takes place linearly throughout the duration of the exposure, and is synchronised with the start and finish of the exposure.

The movement can be effected in various ways. In one form of the invention, the camera lens is mounted so as to be movable relative to the film. In an other form of the invention, the film is supported so as to be movable relative to the lens during the exposure. In a further form of the invention, additional optical means are provided to effect displacement of the image. The movement could be driven in various ways. A separate driving mechanism, electrical or mechanical, could be provided. Alternatively, the driving force could be derived from the camera mechanism or driven by some action of the operator, for example by the pressure on the shutter release button.

Synchronisation of the movement could be by various means, electrical, electro-mechanical, or mechanical, in a similar manner to the synchronisation of movement of the filter members in some of the previously described embodiments of the invention.

The camera can be provided with movable filter members of any of the forms previously described. In operation, alteration of the light path during the exposure means that the images formed in light of different characteristics, for example in light of different colours, are displaced relative to one another on the film to give an effect similar to that achieved in the previously described embodiments by movement of objects in the scene or movement of the camera relative to the scene.

In the form of the invention in which the lens is moved relative to the film, the lens could be mounted in the camera body so as to be movable linearly in a direction parallel to the film plane. For example, as shown diagrammatically in figure 9, the lens 90 could be movable relative to the film holder 92 between the positions shown in solid lines and the position shown in dotted lines.

Alternatively, the lens could be mounted, as illustrated diagrammatically in figure 10, so that it can be tilted about an axis (normally vertical), the axis being displaced from the nodal point of the lens to ensure that tilting of the lens causes movement of the image on the film.

Figures 11 and 12 illustrate diagrammatically forms of the invention in which movement of the film is effected. The movement could be linear, in the film plane, as shown in figure 11, or could be a tilting movement about a normally vertical axis, as shown in figure 12. The movement could be achieved in various ways. For example, the whole of the camera back could be mounted so as to be movable. Alternatively, the film itself could be moved, for example, in the case of roll cameras and minature cameras, by suitably modifying the film transport mechanism. In the case of sheet film cameras the film holder could be mounted so as to be movable.

In the form of the invention in which additional optical means are provided to displace the image during exposure, various optical components, such as mirrors or prisms, could be employed.

For example, figure 13 illustrates diagrammatically a mirror 94 mounted in front of the camera lens 90 for rotation about a vertical axis. The mirror is turned to a pre-determined angle during exposure, for example by means of a stepping motor 96, in such a way that the image of the scene formed on the film is displaced through a pre-determined distance during the exposure. The speed of rotation of the mirror could be made adjustable, through an electronic control device 98, in conjunction with the length of the exposure, to adjust the angle through which the mirror moves during the exposure, thereby to adjust the with of the fringes formed on the image. Other optical elements could be used. For example, the mirror in figure 13 could be replaced by a narrow angle prism. This would have the advantage that the camera could be used in its conventional position, with the lens pointed directly at the scene.

The optical element could be positioned at other points in the optical path, for example between the lens and the film.

In each of the alternatives described, the drive mechanism for effecting movement of the element could be made adjustable by the operator. For example, the mechanism could be arranged so that the operator could select the direction of movement of the element, so as for example to take account of the movement of an object in the scene.

The degree of movement could be made adjustable, to adjust the width of the fringes formed on the image. In this way, movement of the element could be employed not only when photographing a still scene but also when photographing a scene containing movement, for example to avoid fringes of excessive width being caused by a fast moving object in the scene.

The mechanism could be arranged so that it could be disconnected by the operator, if movement of the element is not required in photographing a particular scene.

Instead of moving the element linearly in one direction, other forms of movement could be employed. For example the element could be arranged to move successively in two opposite directions during the exposure, or oscillated a number of times during the exposure. In that case, the start of the exposure would be synchronised with the start of a cycle of oscillation of the element. Instead of moving a single element, two or more elements of the camera could be moved relative to one another.

In yet another form of the invention, the whole optical system of the camera, including the lens and film holder, is movable bodily during the exposure. For example, as illustrated diagrammatically in Figure 14, the lens 90 and film 82, together with the shutter and filter mechanism 100, are movable in synchronism in a direction parallel to the film plane. The elements are mounted, for movement in either direction from a central position, in a housing 102, which also contains a suitable drive and control mechanism for moving the elements. The drive mechanism could be arranged, for example, to effect a continuous oscillatory movement of the elements, with the start of the shutter movement synchronised with the beginning of one cycle of the oscillation. The movement of the elements could be rotational, about a common axis, rather than linear.

In one embodiment of this form of the invention, the optical mechanism, together with the appropriate filter mechanism, is mounted in a conventional camera body, which is itself mounted in a separate housing or cradle together with the drive and control mechanism for effecting linear or rotational movement of the camera body. When taking a photograph, the outerhousing or cradle would be held, or mounted on a tripod, in the usual way. In each of the embodiments employing movement of one or more elements to displace the image on the film, the direction of movement could be selectable by the camera operator such that for each photograph the direction of movement of the element or elements could be chosen with regard to optimising the stereoscopic encoding by taking into account the direction of movement, if any, of the principal objects in the scene being photographed. The speed of movement of the element or elements could be fixed, or could be selectable by the camera operator in order to optimise the balance in the photograph of the stereoscopic encoding and the visible fringing when the photograph is viewed without spectacles.

It will be appreciated that other means could be used for displacing the image during the exposure, for example using electro-optical components which can alter the path of light to displace the image without the need for mechanical movement of the component.

Claims

1. A photographic stills camera provided with means coupled to the camera shutter for modifying the light falling from a scene on to film in the camera during exposure of the film, so that during the exposure a number of successive images of the scene, or of parts of the scene, are recorded on the film in light of different characteristics, preferably light of different colours.

2. A camera as claimed in Claim 1, in which the means for modifying the light falling on to the film comprises a series of filters, and drive means are provided for moving the filters across the optical path of the camera during exposure of the film.

3. A camera as claimed in Claim 2, in which a filter member consisting of two or more portions of different colours, for example two portions of complementary colours such as red as cyan or three colours such as red, blue and green, is arranged to be moved so that each frame of the film is exposed successively in the different colours as the filter member moves across the optical path.

4. A camera as claimed in Claim 3, in which the portions of the filter are arranged so that opposite sequences of colours occur in turn as the filter member moves across the optical path.

5. A camera as claimed in Claim 3, in which the filter member is arranged so that each successive image is divided into a number of areas which are recorded in light of different colours, each area being itself recorded in different colours in the successive images.

6. A camera as claimed in any on of Claims 3. 4 and 5. in which the filter member is a horizontally moveable member or a rotatable disk, coupled to or forming part of the camera shutter.

7. A camera as claimed in any one of Claims 3 to 6, in which the filter member and driving means are mounted in a separate device adapted to be detachably fitted to the lens of a conventional camera.

8. A camera as claimed in Claim 1 or Claim 2, in which the means for modifying the light falling on to the film during exposure comprises an electronic optical filter adapted to modify the light passing through the filter and electronic means for controlling the filter during exposure of the film.

9. A photographic stills camera having means for modifying the light falling on to film in the camera during exposure of the film, so that during the exposure a number of successive images of the scene, or of parts of the scene, are recorded on the film in light of different characteristics, and means for altering the path of light through the optical path of the camera to displace the successive images relative to one another.

10. A camera as claimed in Claim 9, in which the camera lens is mounted so as to be movable relative to the body of the camera, for example in a direction parallel to the film plane or tilting about an axis displaced from the nodal point of the lens, and driving means are provided for moving the lens in synchronism with the exposure of the film.

11. A camera as claimed in Claim 9, in which the film is mounted in a holder adapted to be moved relative to the body of the camera and means are provided for moving the holder during exposure of the film.

12. A camera as claimed in Claim 9, in which the optical system of the camera, including the lens and film holder, is mounted in a separate housing so as to be movable bodily relative to the housing, and drive means are provided for moving the optical system in synchronism with exposure of the film.

13. A camera as claimed in Claim 9, in which additional optical elements are provided in the optical path of the camera arranged to effect displacement of the film during exposure of the film.