GB2100868A - Panoramic camera - Google Patents

Abstract

In the shown panoramic camera of Fig. 1, an outer housing 12 (comprising mirror 20, lens system 18 and slit aperture 63) rotates around a stationary cylinder 14 (which supports a renewable length of film 61 having supply and take-up spools 52 and 54) between stops 64a and 66a. In Fig 3, the spools are situated within the stationary cylinder. In Fig 4, the positions of lens system and mirror are reversed. <IMAGE>

Description

SPECIFICATION Cameras This invention relates to cameras and in particular to cameras which are capable of making a photographic record over a very wide angle of views. Such a camera is ideal for photographic panoramic views.

Cameras of the single lens reflex type can be provided with wide angle lens but the angle of view is still relatively limited. Very wide angle lens of the "fish-eye" type are known and, whilst they are capable of producing interesting and unusual effects, they do this by a gross distortion on the film of the actual scene being photographed.

They cannot simply be used, therefore, to produce a reasonably undistorted view over a wide angle.

To provide very wide angle views without distortion, a number of cameras have been developed. One comprises a camera body which, together with its lens, is slowly swivelled around to pan across the screen. This will provide photographs of, say, an assembled group of people but does require that the subjects be carefully aligned on an arc whose centre coincides with the pivot point of the camera. In addition, an extremely precise arrangement is required to move the film past a slit on which a very small arc of the scene is imaged, that film movement being synchronised with the panning of the camera.

Another camera uses a stationary film which is curved in concave sense and, whilst the camera body remains stationary, the optics are pivoted past the film so that a small slit image is progressively advanced over the concave film surface.

Neither of these cameras is simple and one inevitable drawback is that the angle of the scene which can be photographed is still rather limited, usually not more than 1400.

It is therefore an object of this invention to provide a relatively simple wide angle camera which can photograph a scene of 2700 width or even more.

According to the invention there is provided a photographic camera comprising a central stationary cylinder around a part of which a strip of sensitive photographic film can be positioned with the sensitive emulsion side radially outwardly, an outer light-proof housing rotatable relative the stationary cylinder and supporting an optical system rotatable with the housing relative the cylinder for providing an image at a slit substantially parallel with the axis of the cylinder and axis of rotation, that image being arranged to be focused on photographic film positioned around the cylinder, the optical system including a reflector at 450 to radial direction of other means to reverse the sense of the image at the slot and means for rotating the outer housing relative the stationary cylinder around a radial arc at least as extensive as the radial arc of the film around the cylinder.

Such a camera can take extremely wide angle pictures and produce a flat picture which can be largely free from distortion in the direction of top to bottom of the film although there will be distortion across the very wide picture because the picture will be looked at flat whilst the scene depicted is not flat. That type of distortion is, however, inevitable in most photographs and the final picture from a camera is still very recognisable.

The arc over which the photograph is taken can be relatively large. Thus it can readily be at least 2700 and if the rolls on which fresh and exposed film are housed within the stationary cylinder rather than between the cylinder and outer housing, the arc can be as large as 3400 and can even approach the full 3600.

One important advantage of the invention is that the camera does not need accurate setting up. It is desirable that the axis of rotation be as near vertical as possible and so a spirit level or the like can be provided on the camera. Otherwise the user can simply set up the camera and photograph any panoramic view. Further, the camera can be quite small and portable so can be carried about and used by an amateur whereas previous cameras used for taking wide angle "panned" photographs have tended to be very large and so only useful to professional photographers for certain specialist operations such as photographing groups of people.

The exposure of the photographic film can be varied in two ways, namely the aperture of the lens opening of the optical system and the speed of rotation of the housing relative the cylinder.

This is entirely analogous to a conventional camera where lens aperture and shutter speed control the exposure of the film and so with the camera of the invention the depth of field of the photograph can be chosen by the required choice of lens aperture and corresponding speed of rotation to give the required exposure on the film.

The optical system can use as its lens system for focusing an image of the scene on the slit in front of the film, a conventional lens. In addition, the lens system in a camera according to the invention can be used to its fullest potential which is not usually possible with a conventional camera producing in an instantaneous exposure a square or rectangular image format. Thus, a lens system will inherently produce a circular image and only that portion within a square or rectangle matching the film format size is used and the segments of the image outside that format are not used. For example, for a 25 mm focal length lens producing a rectangular image format of 24 mm x 36 mm, the horizontal angle with the image is 710.In a camera according to the invention, by contrast, an upright slot limits the extent of the image used at any instant but that slot can have a length approximately equal to the diameter of the round image formed by the lens since that slit irriage is thereafter advanced across the film. Therefore, for example, with the same 25 mm focal length lens as above, the resulting image can be about 42 mm high giving an angle with the image of 81 .

Therefore, it can be said that in effect the camera of the invention uses the potentiai of a lens more effectively as compared with a camera producing an instantaneous square or rectangular image format.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a plan sectional diagram of one embodiment of camera according to the invention; Figure 2 is an upright sectional diagram through the embodiment shown in Figure 1; and Figure 3 is a plan diagram similar to Figure 1 of a modified embodiment of camera according to the invention; and Figure 4 is a plan diagram similar to Figure 1 of a further embodiment of camera according to the invention.

The camera 10 shown in Figures 1 and 2 comprises an outer light-tight cylindrical housing 12 coaxially within which is a hollow cylinder 14.

Extending radially out from the housing 1 2 is a tubular arm 16 carrying a lens system 18 in front of which is a reflecting mirror 20 inclined at 450 to the axis of the lens system.

The lower end of the cylinder 14 is closed by a plate 22 to which is fixed a threaded boss 24. The threaded hole 26 of this boss is coaxial with the housing 1 2 and a cylinder 14 and is in the underside of that boss. It is of a size so that it can accept the threaded screw of a conventional photographic tripod.

The lower end of the housing 12 is closed and has a circular hole 30 journalled in a light-tight manner in an annular recess 31 in the boss 24.

The top of the housing 12 is closed by a circular plate 32 fixed to the cylinder 1 4. The plate 32 extends over the top of the housing into abutment with the cylinder wall of the housing 12 and a ring 36 extends radially in from the wall of the housing just below the plate 32 to form a light trap.

Within the hollow cylinder is an electric motor 40 and reduction gearing 42 whose output shaft 44 extends up and out through the plate 32. The motor 40 is driven by an electric battery 45 which can be of the rechargeable type. Alternatively, the motor could be driven by stored spring energy.

Attached to the top of the output shaft 44 is a radial arm 46. This has a length slightly greater than the radius of the housing 12. In turn from the outer end of the arm 46, a further arm 48 extends down and is connected to the housing 12 by a pin 50. Thus, when the motor is energised, it drives the reduction gear box whose output shaft in turn rotates the arm 46 and in turn the housing 12 so that the housing rotates relative the stationary cylinder 14 and boss 24.

A pair of slim spools 52 and 54 are rotatably mounted in the annulus 56 between the cylinder 14 and housing 1 2. These spools can be rotated by knobs 58 attached to the spindles 60 on which the spools are mounted and which extend out through the plate 32. A length of photo-sensitive film 61 extends, emulsion-side radially outwardly, in a convex fashion around the outside of the cylinder 14 from the feed spool 52 to the take-up spool 54, small rollers 60 being provided to guide the film against the cylinder 14.

Leading from the tubular arm 1 6 containing the lens system 1 8 is a wedge-shaped, matt-blacked mask 62 having a narrow slit 63 one to two mm wide at its narrow end Tw s slit 63 is positioned adjacent the film surface since the nearer the slit 63 to that surface in general, the better the definition of the resultir 70we.

A pair of stops 64 and 66 are provided at the limits of rotary mover ,ent oft Ie housing. These stops can be provided with electrical limit switches or the like (not shown) to deactivate the motor at the limit of its operation. In addition, the stops have portions 64a and 66a contiguous with the film surface and positioned between the film surface and the slit 63 in limit positions so as to prevent exposure of the film except during rotary movement of the housing and lens system.

The lens system has a conventional diaphragm 70 to adjust the degree of light passing through the lens system and also to control depth of field.

Further, the lens system can have an adjustable focusing arrangement.

In order to start the operation of the motor an electrical switch (not shown) is provided. In addition, the speed of rotation is preferably also adjustable by inclusion of, for example, appropriate electrical resistances in circuit. In this way, the degree of exposure of the film can be controlled independently of the opening of the lens diaphragm.

In order to ensure that the axis X-X of the cylinder 14 and housing 1 2 are strictly upright, the plate 32 can be provided with a spirit level (not shown).

The operation of the camera loins relatively simple. A photo-sensitive film is loaded by drawing film from the feed spool 52 and passing the film around the cylinder to the take-up spool.

Film is then wound onto the take-up spool 54 until the length of film around the cylinder is unexposed.

The camera is set up on a tripod by attaching the tripod to the boss 24 and levelled. Then the lens system 1 8 is focused and the exposure chosen conventionally and set by appropriate choice of lens aperture opening and speed of rotation of the housing 1 4 relative the cylinder 12 and film.

The user then starts the operation of the motor 40 and the image at the slit is taken around and over the sensitive film surface to give a wide angle image. In the camera 10, this image will be a panoramic image taken over an angle of about 2700. The limit switches stop the operation of the motor once exposure has been made.

After taking this photograph, the camera is readied for another shot by advancing the film until fresh film extends around the cylinder. In the particular example shown, the housing must either be rotated in the opposite direction from taking a photograph while keeping the lens system closed so as to bring the camera back to the position shown in Figure 1. Alternatively, the wedge shaped mask 62 may be shorter than shown so as not to touch the spools 52 and 54 and the spools covered by a suitable mask to prevent further exposure of the film as the slit 63 passes the spools.

The modified camera 80 shown in Figure 3 differs from that shown in Figures 1 and 2 in that the two spools 52 and 54 are positioned within the hollow cylinder 14 rather than in the annulus 56. This has the advantage they do not then obstruct the mask 62 and slit 63 and the latter can now be very close to the emulsion surface.

Further, there is the additional advantage that the camera 80 can photograph a much greater arc of a panoramic view, approximately 3400 in this example. The limit towards obtaining a full 3600 photograph is the size of the gap 82 in the cylinder through which the film passes between the spools and the outer surface of the cylinder.

The camera 100 shown in Figure 4 differs from that shown in Figures 1 and 2 in that the mirror 120 is now at the rear of the lens system 18 and therefore positioned between the lens 1 8 and slit 1 63. This has the advantage that the camera can be made more compact but this is at a cost of reducing slightly the arc over which a panoramic view can be taken to approximately 2500 in the embodiment shown. An increased arc can be achieved by placing the spools 52 and 54 within cylinder 114 in a fashion similar to that shown in Figure 3.

Claims (7)

1. A photographic camera comprising a central stationary cylinder around a part of which a strip of sensitive photographic film can be positioned with the sensitive side radially outwardly, an outer light-proof housing rotatable relative the stationary cylinder and supporting an optical system rotatable with the housing relative the cylinder for providing an image at a slit substantially paralled with the axis of the cylinder and axis of rotation, that image being arranged to be focused on photographic film positioned around the cylinder, the optical system including means to reverse the sense of image at the slit, and means for rotating the outer housing relative the stationary cylinder around a radial arc corresponding to the radial arc of the film around the cylinder.

2. A camera as claimed in Claim 1 in which the means to reverse the sense of the image at the slit comprises a reflector positioned at 450 to the radial direction.

3. A camera as claimed in Claim 2 in which the reflector is positioned between the slit and a lens or lens system.

4. A camera as claimed in any preceding claim in which supply and take-up rolls for fresh and exposed film are provided to hold film extending around the cylinder, the supply and take-up rolls being positioned between the cylinder and housing.

5. A camera as claimed in any of claims 1 to 3 in which supply and take-up rolls for fresh and exposed film are provided to hold the film extending around the cylinder, the supply and take-up rolls being positioned within the cylinder, and openings being provided in the wall of the cylinder for the film to pass from the rolls to around the cylinder.

6. A camera as claimed in any preceding claim in which the speed of rotation of the housing relative the cylinder can be varied to vary the degree of exposure of the film.

7. A photographic camera substantially as herein described with reference to Figures 1 and 2, Figure 3 or Figure 4, of the accompanying drawings.