WO1998036318A1

WO1998036318A1 - Dual focal length camera

Info

Publication number: WO1998036318A1
Application number: PCT/US1998/002476
Authority: WO
Inventors: Stephen D. Fantone
Original assignee: Mobi Corporation
Priority date: 1997-02-18
Filing date: 1998-02-05
Publication date: 1998-08-20
Also published as: AU6274098A

Abstract

Compact dual focal length cameras are disclosed having wide angle and telephoto modes of operation. The ratio of telephoto to wide ratios is at least 3 to 1, but is typically higher so that the cameras can be used in conjunction with binoculars to take telephoto pictures that give the same visual appearance as when the same scenes are observed through binoculars. Compactness and increased focal length are achieved via four mirror (110, 116, 122, 90) arrangements one preferred embodiment of which wraps around the camera film plane (48), and uses a single constant angular velocity shutter (130) for providing both wide angle and telephoto exposure times. Compact, single-use, medium telephoto cameras are also disclosed.

Description

TTTLE: DUAL FOCAL LENGTH CAMERA

CROSS-REFERENCE TO RELATED APPLICATION

This application is a coπtinuation-in-part of commonly owned, copending United States Patent Application Serial No. (My Case No.C-0136/US) filed on February 18, 1997 and entitled "DUAL FOCAL LENGTH CAMERA".

BACKGROUND OF THE TNVFNTTON

1. Field of the invention

This invention generally relates to iow-cost, compact, photographic cameras and, more particularly, to special purpose, compact, dual focal length cameras operable in a wide angle mode for taking wider field of view photographs than normal and a telephoto mode for taking close-up photographs that have the appearance of distant scenes as observed through binoculars having a magnification in the range including 5X-8X.

2. Description of the Prior Art In the last few years, a significant market has developed for simple, low-cost 35 mm cameras ofthe "point and shoot" type. These cameras are available in both the conventional miihiple-usε corxfiguration. which is adapted to have the end-user load and replace the film supply, and a single-use format which comes pre-loaded with film and is intended to be sent back to a factory for film processing. Such single-use 35 mm cameras have become extremely popular because they are perceived as a convenient, low-cost alternative to conventional cameras with replaceable film capability. The single-use cameras typically come with a single lens having a focal length that provides a slightly wider angular view than is considered normal for 35 mm film (usually with a lens having a focal length approximately equal to the firm diagonal to about 50mm). Telephoto and panoramic versions ofthe single-use camera also are available. For prior art examples of such wide angle, telephoto and panoramic single-use cameras, reference is directed to U.S. Patent No. 5,416 574 issued on November 19, 1996 and entitled "LENS-FTTTED PHOTO FILM UNIT FOR USE VVTTH TAKING LENSES OF DIFFERENT FOCAL LENGTH". Also known in the prior art are single-use, dual focal length cameras having two taking lenses, each having a different focal length. Usually, these cameras include a wide angle lens for taking wide angle photographs and a telephoto lens for taking close up photographs of distant scenes. The wide angle lens typically has a focal length in the range of 30-40 mm, and the telephoto lens typically is in the short telephoto range of 70- 90 mm, thus providing a modest telephoto to wide angle focal length ratio of about 2:1, or at best 3:1.

The wide angle lens is generally mounted on the front of camera forward of an unfolded, relatively short, direct optical path from the lens to the film plane, which is located at the back of the camera. Because the imaging optical path for the telephoto lens is approximately two to three times longer th«" that ofthe wide angle lens, and it is desirable to keep the size ofthe camera housing relatively compact, these cameras generally use two internal mirrors (usually one mirror is moveable) to define a compact, folded optical path between the telephoto lens and the film plane. For examples of such dual focal length cameras, reference is directed to: U.S.

Patent No. 4,609,270 issued September 2, 1986 and entitled "CAMERA WITH INTERCHANGEABLE TAKING LENSES; U.S. Patent No. 4, 772, 903 issued September 20, 1988 and entitled "DUAL LENS CAMERA"; and U.S. Patent No. 4,989,026 issued January 29, 1991 and entitled "BIFOCAL CAMERA". While these dual focal length cameras perform very well when operated in the telephoto mode for taking photographs of scenes or subjects at moderate distances, photographs taken offer away subjects, such as athletes at sporting events or performers at entertainment events, are very disappointing because the subjects of principal interest are relatively small in the photograph and stϋl appear to be very distant. To obtain a close-up view of distant subjects at such events, people will often use a pair of binoculars providing image magnification in the range of 5X-8X. However, when they take a photograph ofthe same scene using the dual focal length camera's 70- 90 mm telephoto lens, the resultant photographic image ofthe scene is only about one- half to one-third the size ofthe image provided by the binoculars. This invention is intended to fulfill an identifiable need for a compact, low-cost, dual focal length camera to be used in conjunction with binoculars of modest power at sporting, entertainment, or other events for taking close up photographs that have the appearance of distant scenes as observed through binoculars having a magnification in the range including 5X-8X.

In binocular jargon, one often refers to the the width ofthe field covered at a distance of 1000 yards, and this ususaHy corresponds to the diameter of a circle since most binoculars have circular fields of view. To achieve field coverage comparable to 5X-8X binoculars at 1000 yards requires a telephoto lens whose focal length is approximately between 140 to 240 mm, which is substantially longer than the typical telephoto lens provided in such dual focal length cameras.

However, a dual focal length 35 mm camera incorporating a telephoto lens in the 140-240 mm focal length lens range would require an unacceptably large and ergonomically undesirable camera, even if one adopts the above noted prior art practice of using two internal mirrors to define a folded optical path between the telephoto lens and the camera's film plane.

Therefore, it is a principal object of this invention to provide a compact, dual focal lens camera which is operable in a telephoto mode to take close-up photographs that have the appearance of distant scenes as observed through binoculars having a magnification in the range including 5X - 8X.

Another object of this invention is to provide such a camera in which the telephoto optical system for taking such close-up photographs in configured in ways that fit into a compact camera housing that is ergonomically desirable and is only slightly larger than the housing used in conventional dual focal camera. Yet another object of this invention is to provide such a camera that is inexpensive to manufacture thereby making it economically feasible to market the camera in a single-use camera configuration.

Another object of this invention is provide a compact, low-cost, dual focal length camera that is specially designed to be a complementary companion product for use in conjunction with a pair of low cost binoculars, such as those disclosed in United States Patent Application Serial No. 08/320,920 filed on October 11, 1994 and entitled "Low- Cost, Light- Weight, Compact Binoculars".

Another object ofthe invention is to provide a compact, dual focal length optical system that is capable of imaging onto a photodetector in telephoto and wide angle 5 modes of operation.

Another object ofthe invention is to provide compact, single-use cameras with medium telephoto lenses.

Other objects ofthe mvention will in part be obvious and will in part appear hereinafter. A full understanding ofthe invention will best be had from reading the l o detailed description to follow in connection with the detailed drawings.

SUMMARY OF THE INVENTION

The present invention accomplishes the above noted objectives by providing a novel, compact, dual focal length camera operable in a wide angle mode for taking wide 15 angle photographs and a telephoto mode for taking close up photographs that have the appearance of distant scenes as observed through binoculars having a magnification in the range including 5X-8X.

This inventive camera includes a compact housing, means for defining a film plane within the housing and wide angle and telephoto lens systems. 0 The wide angle lens system functions to form a wide angle image of a scene at the film plane and includes a wide angle lens, having a given focal length, for directing imaging bearing hght along a first optical path to the film plane for use in the wide angle mode of operation.

The telephoto lens system functions to form a magnified image of a scene at the 5 film plane and includes a telephoto lens, having a focal length that is at least three times longer than the given focal length ofthe wide angle lens.

The camera also includes four mirrors for providing a folded optical path between the telephoto lens system and the film plane.

At least one of he four mirrors is mounted for movement between a first position 0 in which h permits scene light emerging from the wide angle lens system to impinge on the film plane while preventing scene light from emerging from the telephoto lens system from lπipinging on the film plane and a second position in which it prevents scene light emerging from the wide angle optical system from impinging on the film plane while directing scene fight emerging from the telephoto optical system onto the film plane. The camera is adapted to be switched between wide angle and telephoto modes of operation by having the camera operator actuate means for moving the moveable mirror between its the first and second positions.

In one prefered emrx>diment, the four rnirrors actually wrap around the film plane to provide compact and ergonomically sound design that is also aesthetically pleasing. Other preferred embodiments have all four mirrors located forward ofthe film plane. aD to one side of it.

A number of lens designs are provided to demonstrate the range of optical designs that may be combined to achieve the desired telephoto to wide angle ratios while still remaining compact. Compact, single-use, medium telephoto cameras are also disclosed.

DESCRIPTION OF THE DRAWINGS

The structure and operation ofthe invention, together with the other objects and advantages thereof, may best be understood by reading the detailed description in connection with the drawings wherein the same parts appearing in different drawings have the same reference number and wherein:

Figure 1 is a dkgrammatic front perspective view of a preferred embodiment of the inventive compact, dual focal length camera;

Fig. 2 is a diagrammatic rear perspective view ofthe camera shown in Fig. 1 ; Fig. 3 is a dkgrammatic vertical section ofthe camera shown in Fig. 1 , taken along line 3-3, showing a movable mirror assembly in a first position for taking wide- angle photographs;

Fig. 4 is a α^grarnmatic vertical section similar to that shown in Fig. 3 except that the moveable inirror is shown in its second position for taking telephoto photographs: Fig. 5 is a diagrammatic front elevational view of a bow tie shaped camera shutter shown in its normal light blocking position in solid fines and its fight unblocking film exposure position in dotted lines;

Fig. 6 is a lens construction diagram showing a 41.5 mm wide angle lens in its unfolded configuration;

Fig. 7 is a lens construction diagram showing a 140 mm telephoto lens in its unfolded configuration;

Fig. 8 is a lens construction diagram showing a 166 mm telephoto lens in its unfolded configuration;

Fig. 9 is a lens construction diagram showing a 204 mm telephoto lens in its unfolded configuration;

Fig. 10 is a lens construction diagram showing a 256 mm telephoto lens in its unfolded configuration;

Fig. 11 is a lens construction diagram showing a 31.7 mm wide angle lens in its unfolded configuration;

Fig. 12 is a lens construction diagram showing a 48.68 mm lens in its unfolded configuration;

Fig. 13 is a dkgrammatic front-elevational view of a first alternative preferred embodiment ofthe inventive, compact, dual focal length camera showing selected components of its wide angle and telephoto optical systems;

Fig. 13a is a diagrammatic side-elevational view ofthe camera shown in Fig. 13; Fig. 14 is a diagrammatic isometric drawing of a second alternative preferred embodiment ofthe inventive, compact, dual focal length camera showing selected components of its wide angle and telephoto optical systems; Fig. 14a is a diagrammatic front-elevational view ofthe camera shown in Fig. 14;

Fig. 14b is a dkgrammatic side-elevational view ofthe camera shown in Fig. 14; Fig. 14c is a dkgrammatic top-elevational view ofthe camera shown in Fig. 14; Fig. 15 is a dkgrarnmatic front-elevational view of a third alternative preferred embodiment ofthe inventive, compact, dual focal length camera showing selected components of its wide angle and telephoto optical systems; Fig. 15a is a diagrammatic side-elevational view ofthe camera shown in Fig. 15; Fig. 15b is a diagrammatic top-elevational view ofthe camera shown in Fig. 15; and

Fig. 16 is a d grammatic elevational sectional view showing an alternative embodiment ofthe invention.

DETAILED DESrRTPTTnN

Figure 1 shows a first preferred enibodiment of a compact, dual focal camera 10 ofthe present invention. Camera 10 includes a compact camera housing 12 formed by a forward wall 14, an opposite rear wall 16, a top wall 18, an opposite bottom wall 20, and opposed side walls 22 and 24. Integrally formed with rear wall 16 and centrally disposed thereon is a rearwardly extending housing section 26, as best shown in Fig. 2, for supporting a pair of internal mirrors and for enclosing a segment of a telephoto optical path defined in part by the mirrors as will become apparent later. Section 26 has a generally trapezoidal, readwardly extending vertical cross section and is formed by inclined rear wall sections 28, 29 and 30 and opposed side wall sections wall sections 32 and 34.

Camera 10 is ofthe dual focal length type that employs two separate optical image forming systems for taking pictures on the same film format but having different angular perspectives and image πagnification defined by the focal length, fi n format, and lens design used in each ofthe two optical system.

As will become apparent, camera 10 has a primary or first optical system having a relatively short focal length for taking pictures that fall within a range classified by those having ordinary skul in the art as ''normal" (or "standard") to " very wide angle" and an auxiliary or second optical system having a relatively longer focal length for taking pictures that fall within a range of image formats classified by those having ordinary skill in the art as "medium telephoto". As will be discussed in detail later, the medium telephoto range has been chosen for the auxiliary optical system to provide camera 10 with the capability of taking close-up photographs that have the appearance of distant scenes as observed through binoculars having a magnification in the range including, but not necessarily limited to, 5X - 8X.

Where camera 10 is configured to use conventional 35mm photographic film (24mm X 36mm image area), the primary optical system would typically have a focal length somewhere between 50mm for the normal or standard format and 28mm for a very wide angle format. The corresponding medium telephoto or second optical system would typically have a focal length in the range of 120 mm - 240 mm,

With reference to Fig.l, the illustrated camera 10 includes a lens 36, aligned with a first lens opening 38 in housing forward wall 14, that forms part ofthe shorter focal length primary optical imaging system and a lens 40, aligned with a second lens opening 42 in forward wall 14 above opening 38, that forms part ofthe longer focal length auxiliary optical system.

Camera 10 also includes a conventional direct viewfinder preferably having a forward lens element 44 which is shown at the right upper end of forward housing wall 14, as viewed in Fig. 1, and an aligned rear lens element 45 shown in the upper left end of rear wall 16 as viewed in Fig. 2. These two lens elements, 44 and 45, are preferably in the form of a well-known reversed Galilean telescope, but may also take the form of simpler direct viewfinders. In either case, appropriate masks are to be used with the viewfinder to provide correct filming corresponding to the wide angle and telephoto modes of operation. Mounted on top wall 18 is a conventional shutter actuation button 46.

As best shown in Fig 2. camera 10 also has rotatable knob 47 mounted on housing side wall 24, which is actuable by the camera operator to move a later to be described mirror between a first or wide angle exposure position and a second or telephoto exposure position.

Camera 10 is designed to be a simply constructed, low-cost, single-use, dual focal length camera ofthe "point and shoot" type . The term "single-use" as used herein means that the camera comes from the factory pre-loaded with a single roll of film that is not directly accessible to, nor is it intended to be handled or replaced by, the end user. After all ofthe frames in the roll of film have been exposed, the entire camera is sent back to a factory, or an independent film processor, where the film is removed and processed. However, it should be clearly understood that the present invention is not limited for use only in single-use cameras but may also be used in more conventional cameras that are designed to have the film loaded and replaced by the end user. With reference to Fig. 3 and Fig. 4, the longer focal length auxiliary or medium telephoto second optical system is operatively accommodated within the relatively small and compact camera housing 12 by using an ammgement of four (4) mirrors to provide a four segment folded optical path including a telephoto lens system, formed in part by lens 40, and the camera's internal fihn exposure plane 48 which is common to both the primary and auxiliary optical systems.

This particular preferred embodiment of camera 10 is characterized by the telephoto system folded optical path which has a portion thereof that wraps around behind film plane 48. As will become apparent later, other preferred embodiments of camera 10 will include folded telephoto optical that have all portions thereof located in front ofthe film plane 48.

As shown in Fig. 3 and Fig. 4, camera 10 includes a vertically disposed internal, film plane defining, film strip support plate member 50 which extends laterally between the side walls 22 and 24 ofthe housing 12 and is spaced forwardly from rear housing wall 16 and the mirror housing section 26 thereon in orthogonal or normal relation to the horizontal optical axis 52 ofthe primary taking lens 36 that is mounted in a conventional lens mount (not shown) just behind housing forward wall 14 in alignment with lens opening 38.

The support plate member 50 is preferably a molded plastic part that includes a forward facing vertical surface 54 against which a portion of a film strip 56, between supply and take-up rolls (not shown), bears to locate that portion ofthe film 56 at the fihn exposure or object plane 48. Coupled to and extending forwardly of fihn support member 50 is light blocking tube or baffle assembly 58, to be described in detail later, that surrounds the rear portion of the image bearing light path from lens 36 to exposure plane 48 to block unwanted stray fight that may enter housing 12 from reaching and exposing that portion ofthe film 56 at the exposure position. Baffle assembly 58 includes upper and lower flange portions 60 and 62, respectively, which snap into conmlementary flange portions 64 and 66 of member 50 to form upper and lower, laterally extending guided channels 68 and 70 for receiving the upper and lower edges ofthe film strip 56 to πiaintain it in bearing relation against the forward surface 54 of member 50 to locate that portion ofthe fihn 56 in the exposure position at the camera's fihn plane 48.

By accurately locating forward film bearing surface 54 of fihn support member 50 whh respect to the primary and auxiliary optical systems, surface 54 serves as the means for defining the camera's film plane 48.

Positioned behind camera housing forward wall 14 in covering relation to the both the primary lens 36 and auxiliary lens 40 is a an " L ^u shaped lens aperture defining and shutter mounting member 72 having a vertically disposed section 74, having its upper end attached to the inside of housing top wall 18, and a horizontally disposed section 76 having its forward end attached to the inside of housing forward wall 14 below the lower lens opening 38. As viewed in the vertical cross sections of Fig. 3 and Fig. 4, the light baffle assembly 58 includes an upper portion 78 which extends forwardly from flange 60 and has its forward end attached to the back side ofthe vertical section 74 of member 72 and a lower portion 80 that extends forwardly and has its forward end attached to the inside of housing wall 14 just below section 76 of member 72. Lower portion 80 of baffle 58 includes a telephoto light path opening 82 therein (best shown in Fig. 4) which is adapted to be selectively blocked by a moveable mirror assembly 86 located it its first position when camera 10 is configured in its wide angle mode of operation as shown in Fig. 3, and second position when mirror assembly 86 is moved to its unblocking configuration shown in Fig. 4 to configure camera 10 for telephoto operation. Assembly 86 comprises a mirror support plate 88, having a mirror 90 attached to the underside thereof, and an upstanding flange 92 formed at the forward end of plate 88 having its upper end fixedly attached to a laterally extending, horizontal shaft 94 which is mounted in housing end wall 24 for rotational movement about the axis of shaft 94. This shaft 94 extends through wall 24 where it is attached to the knob 47 that is adapted to be rotated by the user to pivotally move assembly 86 and the mirror 90 thereon between the first and second position. Thus, the minor support 88 plate, in cornbination with flange 92, shaft 94 and the knob 47 at the distal end thereof constitute means, actuable by the camera operator, for moving moveable mirror 90 between its said first and second positions. As noted earlier, dual focal length camera 10 includes a primary optical system having a relatively short focal length for taking normal to wide- angle format photographs and an auxiliary or telephoto optical system for taking close-up photographs having the appearance of distant scenes as observed through binoculars having a magnification in the range including 5X-8X. In this illustrated preferred embodiment of camera 10, the primary optical system includes a primary lens system in the form ofthe single or singlet taking lens 36 and a corresponding aperture opening 98 formed in lower portion of lens aperture defining member 72 so that aperture opening 98 is in arignmpnt with the optical axis 52 of lens 36. With the mirror 90 in its first or horizontal position, shown in Fig. 3, where it blocks opening 82 and does not intrude into the optical imaging path of taking lens 36, the camera is configured for its wide angle mode of operation wherein lens 36 and its corresponding aperture opening 98 provide a focused image of a scene at the fihn plane 48.

The illustratεd auxiliary or telephoto optical system includes a two-element medium telephoto lens system 100 comprising: the first or front lens element 40, aligned with opening 42 in wall 14 and mounted so its optical axis 102 is substantially parallel to the optical axis 52 of lens 36 and is orthogonal or normal to the camera's fihn plan 48; a corresponding aperture opening 104 formed in the upper portion ofthe lens aperture defining member 72 so that aperture opening 104 is aligned with the optic axis 102 of lens 40; and a second or rear lens element 106 fixedly mounted between the top of film support member 50 and the underside of housing wall 18 behind aperture denning member 72 such that it is in alignment with aperture opening 104 and its optical axis 108 coincides with the optical axis 102 ofthe front lens element 40.

Compared with lens 36, the medium telephoto lens 100 has a relatively long focal length requiring a relatively longer optical path to the film exposure plane 48. As a basis for comparison, the term short telephoto lens (typically a portrait lens) as used herein refers to lenses having a focal length in the range of 70 mm -105 mm, and the term medium telephoto lens as used herein refers to lenses having a focal length in the range of 120 mm - 240 mm for 35 mm formatted film. It should be noted that invention can be practiced with film formats other than 35 mm, and these formats include the most recent APS format. In addition, it will be appreciated that the invention can be used whh non- film photodetectors such as digital imaging arrays as, for example, CCD arrays.

As noted earlier, dual focal length cameras known in the prior art typically use a short telephoto lens for the auxiliary optical systems. In order to accommodate the longer optical path ofthe short telephoto lens (relative to the shorter focal length wide angle or normal lens) and yet maintain a compact camera configuration, such cameras employ a pair of rnirrors to fold the optical path between the short telephoto lens system and the film plane into a space saving Z-folded configuration.

However, using the same two mirror, Z-fold approach when the auxiliary optical systems employs a longer focal length medium telephoto lens would substantially and undesirably increase the dimensions ofthe camera housing thereby losing its compact characteristic.

The term "compact' as applied to photographic cameras is a relative term because the size ofthe film used therein will dictate certain minimum camera dimensions relating to the optical path lengths required to provide the proper size image for that film format. While the inventive aspects of camera 10 are not hmited to configurations designed for conventional 35 m film, examples ofthe specific lenses and optical paths will be given for cameras that are adapted to use 35mm fihn because it is by far the most common size film used today. Therefore, the term "compact" when used herein for cameras embodying the present invention that are designed for 35 mm firm will mean cameras having only slightly larger overall size compared to popular 35 mm point and shoot, dual focal length cameras (single and multiple use) that are commercially available at this time while retaining desirable ergonomic features, convenience of use and are easy to carry. To retain compactness while accommodating the longer exposure paths length required by the medium telephoto lens 100, camera 10 employs a four mirror system to fold the relatively long optical path between the medium telephoto lens 100 and the film plane 48. As best shown in Fig. 3 and Fig. 4, this four rnirror system includes a first mirror 110, fixedly mounted on inclined housing wall section 28 behind lens element 106 and the film plane 48 in alignment with and at a 45° angle to the optical axis 108 of lens 106 for folding the image bearing light optical path downwardly, at an angle of 90 ,o whh respect to optical axis 106 along a principal optical path segment 114 behind the film plane 48 to a second mirror 116. Mirror 116 is fixedly mounted on inclined housing wall section 30 at a 45° angle to optical path segment 114 to fold or bend the optical path through 90° along principal segment 120 forwardly and past the film plane 48 to a third mirror 122.

Mirror 122 is fixedly mounted on a fixed internal mirror support member 124, extending between housing wafls 14 and 20, to locate mirror 122 at a 45° angle with respect to optical path segment 120 thereby reflecting image bearing light upwardly and folding the optical path through 90° with respect to path segment 120, along optical path segment 126.

For the telephoto mode of operation, the camera operator has turned the knob 47 to pivot and locate the moveable mirror 90 in its raised telephoto or second position, best shown in solid lines in Fig. 4, unblocking opening 82 in the baffle member 58 and wherein its reflective surface is at a 45° angle to the optical path segment 126 and the fihn plane 48 to bend or fold the optical path rearwardly through 90°, whh respect to path segment 126, along path segment 128 to focus image bearing light on the fihn 56 at the exposure plane 48. This last optical path segment 128 coincides whh the rearward portion ofthe optical path between lens 36 and the film plane when the camera is operated in the wide angle mode employing the primary optical system. When moveable mirror assembly 86, and mirror 90 thereon, are in the raised telephoto position of Fig.4, the trailing edge of mirror 90 fits into an edge receiving notch 129 in upper baffle member 78 forming a light seal between the raise mirror 90 which extends across the interior of baffle 58 in Kght blocking relationship thereto where it prevents scene light emerging from the wide angle lens system from impinging on the fihn plane while directing scene light emerging from the telephoto lens system onto the film plane.

For wide angle operation, the camera operator turns the knob 47 to pivot the moveable mirror assembly downwardly to the position shown in Fig. 3 wherein mirror 90 is in covering, light blockmg relation to the opening 82 in the baffle member 58 wherein rnirror 90 permits scene light emerging from the wide angle lens system to pinge ₀n the film plane 48 while preventing light emerging from the telephoto lens system and attempting to pass through opening 82 from impinging upon the film plane 48.

To manage image bearing fight trarLsmission within camera housmg 12 for film exposure purposes, camera 10 preferably uses a single shutter mechanism 130, for both the wide angle and telephoto taking optical paths, in combination with moveable mirror assembly 86 and the mirror 90 thereon.

Whh reference to Figs. 3, 4 and 5, shutter mechanism 130 includes a hght opaque bow tie shaped shutter blade 132 which includes a centrally disposed rearwardly extending fixed shaft 134 which is mounted in a bearing in member 72 for rotation about the axis of shaft 134 between h light blocking normal position shown in solid fines in Fig. 5 wherein h covers aperture openings 98 and 104 in section 74 of member 72 and blocks transmission of image bearing light therethrough and a fihn exposure position, show in dotted lines in Fig. 5, where shutter blade 132 has been pivoted about shaft 134 so h is in unblocking relation to aperture openings 98 and 104 to permh trarismission of image bearing light therethrough towards and along the previously noted optical paths ofthe first and second optical systems. Whh this single shutter design, the wide angle aperture 98 and the telephoto aperture 104 are simultaneously unblocked during both the wide angle and telephoto modes of operation when blade 132 moves to its unblocking position, allowing image bearing light from both lens systems to enter camera housing 12.

At noted earher, the moveable mirror 90 on mirror assembly 86 is moved between hs first and second positions to create the necessary light seals to prevent unwanted light allowed to enter the camera housing by the shutter mechanism 130 from impinging upon the film.

The illustrated single shutter mechanism 130 is designed to have shutter blade 132 rotate at fixed angular velocity between hs light blocking and unblocking positions. As will become apparent, the design ofthe wide angle and telephoto lenses can be optimized for use with the single shutter mechanism 130 having a fixed angular velocity so that both the wide angle and telephoto taking paths can be used to deliver substantially the same exposure for a given film speed. As shown in Fig. 5, the shutter mechanism 130 further includes a spring 136 coiled around shaft 134 having one end fixed to blade 132 and hs opposhe end mechanically grounded on or fixed to member 74 so as to impart a normal counterclockwise rotation bias and urge the trafiing edge ofthe upper blade portion against a fixed stop 138 mounted on member 74 to locate blade 132 in hs normal light blocking position shown in solid lines.

Shutter mechanism 130 further includes means, in the form of a dkgrammatically illustrated blade striker mechanism 140, for striking the trailing edge ofthe upper portion of blade 132 whh a known constant force to cause blade 132 to rotate in the clockwise direction about the axis of shaft 134, against the counter-clockwise bias of spring 136, at a fixed angular velocity from the blocking position to the unblocking position. Blade 132 continues to rotate in the clockwise direction until the leading edge of hs lower blade portion engages a resilient stop 142 fixedly mounted on member 74. Stop 142 is formed of a resilient material such as rubber or the like, and serves as a resiliently defoπnahle bumper for bouncing the blade 132 back in the opposhe direction whh a given constant force so that blade 132 then rotates in the clockwise direction at the fixed angular velocity to its closed position where the force of spring 136 holds blade 132 against stop 138.

The illustrated striker mechanism 140 include a V-shaped arm 144 that is pivotally mounted at 146 on member 74. The upper end of arm 144 is connected to shutter action button 46 and the opposhe end of arm 144 is positioned against the traihng edge of blade 132 above stop 138. When the camera operator depresses button 46, this action pivots arm 144 about p vot 146 in a counter-clockwise direction and the opposhe end of arm 144 strikes blade 132 whh a predetermined given force to rotate the blade 132 in the clockwise direction at the fixed angular velocity. Although not shown in the drawing, the arm 144 is spring biased to return to hs normal position following the depression of button 46.

A variety of simple, low-cost constant or fixed angular velochy shutter mechanisms are well -known in the photographic arts and may be used in camera 10, in place ofthe illustrated shutter mechanism 130, to provide such a fixed angular velochy shutter.

With moveable mirror 90 in hs wide angle mode position of Fig. 3 blocking opening 82, camera 10 is ready to take a wide angle picture. Upon actuation ofthe shutter 130* both the wide «-0# βad telephoto apertures 98 and 104 are unblocked and light emerging from the wide angle lens system impinges upon the film plane 48 to expose a frame 56 ofthe film while the mirror 90 blocks light emerging from the telephoto lens system from impinging on the film plane 48 and jtøerfering whh the exposure ofthe film

Whh the moveable mirror 90 in hs raised telephoto mode operative position blocking or fight sealing the forward end of baffle 58 in cormπunication with the wide angle aperture 98 while unblocking baffle openmg 82 and positioning mirror 90 to direct light emerging from the telephoto lens system, camera 10 is ready to take a telephoto picture. Upon actuation of shutter mechanism 130, both the wide angle and telephoto apertures 98 and 104 are unblocked and light emerging from the wide angle lens system impinges upon the back side of raised mirror 90 and is blocked or prevented from impinging upon the fihn plane 48 while the forward side ofthe nrirror 90 directs light emerging from the telephoto lens system to the film plane 48 to expose ofthe film

Thus, camera 10 has four rmrrors for providing a folded optical path between the telephoto lens system and the film plane, at least one ofthe four mirrors being mounted for movement between a first position in which h permits scene emerging from the wide angle lens system to impinge on the film plane while preventing scene light from emerging from the telephoto lens system from impinging on the film plane and a second position in which h prevents scene fight emerging from the wide angle optical system from impinging on the film plane while directing scene light emerging from the telephoto optical system onto the film plane. Of importance in the operation of camera 10 are other factors including exposure times, depth of field, f number ofthe lens and the motion stopping capability ofthe shutter.

Experiments have indicated that the medium telephoto lens 100 would require a shutter speed of 1 /l 50* of a second or faster to prevent objectionable motion blurring. However, the shorter primary taking lens 36 can utilize a much longer exposure , e.g., in the range of l/40th of a second, because the shorter focal length produces motion blurring in proportion to the focal length ofthe lens.

To provide for a reasonable depth of field, the ^number ofthe longer focal length medium telephoto lens 100 must be relatively high, typically on the order of 16-20.

To illustrate how various system parameters impact the determination ofthe optical systems of camera 10, it will be assumed, for the moment, that the primary lens 36 has a baseline focal length of 40 mm and the medium telephoto lens 100 has a baseline focal length of 160 mm. These focal length values along whh illustrative values for other optical system parameters are shown in the following Table A.

Table A SYSTEM PARAMETERS

By operating the two optical systems in this manner, the faster shutter speed for the medium telephoto lens 100 is compensated for by the decreased f/number (larger aperture). In approaching the system design in this way, the mechanical design ofthe shutter presents a substantial challenge. In comparison whh the shutter speed for the wide angle lens 36, the shutter for the telephoto lens 100 must open and close an aperture that is eight (8) times the diameter ofthe wide angle lens aperture in one fourth (1/4) the time. With linear velochy, this is a factor of thirty two (32) in shutter blade speed.

Another design approach is to operate the wide angle optics at a faster f7number (for example, F/13). This requires a larger lens openmg ( for example, a 3mm aperture stop) and a shutter which operates nine (9) times faster (1/360 second). In this case, the linear velochy ofthe shutter blades for both wide angle and telephoto lenses is equal as shown in the following calculation.

As is well known in the art, shutter blade velochy is proportional to aperture stop diameter divided by exposure time.

Table B Shutter Blade Velochy Calculation

As those skilled in the art will appreciate, by optimizing the design ofthe two optical systems so that each system uses the same shutter blade angular velochy, the design ofthe shutter may be substantially simplified thereby allowing the use in camera 10 of a low-cost common shutter that operates at a single fixed angular velocity whh only a difference in aperture diameter between the wide angle and telephoto optical systems. It win also be evident that the radial distance from the shutter pivot point to the respective apertures can be adjusted as an additional parameter available as a means of controlling shutter speed whh the constant angular velochy shutter preferably used here. For consistency in the various examples to follow, h shall be assumed the speed of the film to be used with these optical systems is in the range of ASA 700-1600. Two preferred lens designs that have been optimized for use whh a single shutter mechanism having a fixed angular velochy so that both the wide angle and telephoto taking paths can be used to deliver substantially the same exposure for a given film speed are presented in Tables 1 and 2 which follow.

Table 1 presents the constructional data and design parameters for a wide angle singlet, meniscus in form, that has an effective focal length of 41.5mm and an f/humber = 14.25. The constructional data of Table 1, where the data is in nnllimeters, should be used in reference to Fig. 6, which shows the wide angle lens in hs unfolded configuration whh surfaces 2 and 3 corresponding to ofthe singlet's front and rear surfaces. Surfaces beyond 2 and 3 in the constructional data are mirror locations as will be understood by those skilled in the art. Surface 2 here is aspheric and is in accordance whh the aspheric coefficients that appear in Table 1. The aspheric coefficients are based on the well- known aspheric equation for the SAG at a surface, Le., the departure ofthe surface from s apical radius, and is given by:

C= CURVATURE CC ' = CONIC CONSTANT

>=v^

TABLE 1

The telephoto design whose constructional data appears in Table 2 is a two- element lens made of acrylic whh one aspheric surface. It appears in Fig. 7 where h is shown in hs unfolded configuration, and has an effective focal length of 140mm whh an f/number = 13.96. Here, again surfaces beyond surface 7 are mirror locations. The telephoto to wide angle ratio of focal lengths ofthe lenses of Tables 1 and 2 is 140/41.5 or 3.37.

TABLE 2

Table 3 represents yet another telephoto lens design. This lens, which is shown unfolded in Fig. 8, is also of all acrylic design. It has an effective focal length of 166mm and a f/number of 16.37. Surface 6 is aspheric and is the first surface ofthe last elemem.

TABLE 3

Table 4 presents the constructional data for a 204mm telephoto design that has an f number of 19.54 and appears in Fig. 9 in hs unfolded configuration. This is a two- element, all plastic design, whh the first element of acrylic and the second of styrene for color correction purposes. Surface 6, the first surface ofthe last styrene element, is aspheric.

TABLE 4

MISSING UPON TIME OF PUBLICATION

As mentioned previously, this invention is intended to fulfill an identifiable need for a compact, low cost, dual focal length camera to be used in conjunction with binoculars of modest power at sporting, entertainment or other events for taking close up

5 photographs whose appearance is comparable to that of distant scenes as observed through binoculars having a magnification in the range including 5X-8X.

In binocular jargon, one specifies the width ofthe field covered at a distance of 1000 yards. To achieve field coverage comparable to 5X-8X binoculars at 1000 yards requires a telephoto lens whose focal length is somewhere between 140 to 240 mm, l o which is substantially longer than the normal 30-40 mm wide angle typically provided in such dual focal length cameras. With pictures taken with a lens with a focal length between about 140 and 200 mm, the visual impression ofthe scale of subjects in the picture approximates the same scale those objects appear to have when observing them through binoculars.

15 To satisfy the foregoing requirements demanding that the telephoto pictures mimic the binocular view obviously requires telephoto focal lengths comparable to those described above while still having a compact camera. During the design of camera 10 a useful design rule emerged that satisfies all ofthe requirements for space and optical performance. Referring now to Fig. 4, it can be shown that the size ofthe camera and

20 the optical path length available for the telephoto design are related to the height ofthe film format and the focal length ofthe wide angle or primary lens focal length as follows:

TFPL(telephoto path length) = 2 (H_f + EFF_*«),

25 where H_f is the height ofthe film format and EFF«, is the effective focal length ofthe wide angle design.

The foregoing relationship for the TFPL is an expression that depends on film format height and wide angle focal length assumes that the space needed for fitting the four rnirror system around the fihn plane ofthe preferred embodiment of Figs. 1 through 4 can be expressed as percentage ofthe film height, and has been ariproximated to be 15% of Hf. This approximation, of course, can be sensibly altered if needs dictate, and such an alteration will slightly alter the above relationship, but not dramatically. Once the film height is determined and the choice of primary focal length is made, h can be seen that the vertical section ofthe camera, which is hs profile at least in the plane containing the optical axes ofthe primary and secondary lenses, is set as is the optical path into which the telephoto design must be fit. Depending on the telephoto to wide angle ratio, these determinations wfll in turn set the back focal distance available for the telephoto or longer focal length system, and this, in turn, dictates whether a traditional telephoto design will be required where the effective focal length is longer than the back focal length.

To take some examples of how this works, assume that 35mm fihn is to be used having a film height of 35 mm (mchiding sprocket holes), and one desires a primary taking lens whh an effective focal length of 28mm. Under these conditions, the TFPL is 126 mm. Therefore, if one wants a focal length longer that the available 126mm physical distance, a telephoto design must be employed. For the above conditions then, if a range of medium telephoto designs from, say 120 to 240mm, is desired, aD focal length designs in excess of 126mm would have to be traditional telephoto designs. If one increases the focal length ofthe wide angle design to, say 38mm, then the physical space for the longer focal length lens becomes 146mm, and for a primary lens design whh an EFF of 50mm, the longer focal length lens can fit into 170mm of physical path length.

It should be clear from the foregoing that the film format vertical size, or the size of any other photodetector used, and the effective focal length ofthe primary, direct or unfolded path of focal length, determine the camera or imaging system profile size and the space available for the longer focal length design. Moreover, it should also be apparent the minimum telephoto to wide angle ratio is also dependent on the foregoing rektionship. For 35 mm fihn whh a normal lens of 50mm, the physical path length available for the longer ofthe focal length lenses for the four mirror camera design is 170mm where the telephoto to wide angle ratio is 3.4. Thus, this camera design permits minimum telephoto to wide angle ratios of 3.4:1 while still remaining compact and ergonomicany sound. While ratios of 3.4:1 represent the bottom end ofthe range, h is clear that as the wide angle lens focal length becomes smaller, say approaching 28mm, and the longer focal length becomes larger, say approaching 240mm, the ratio approaches 8.56, and ratios whhin this range may be achieved whh relatively simple telephoto designs, some of which have been described previously.

Figs. 13, 14 and 15 show cameras 210, 310 and 410, which are respectively first second and third ahemative

While the previously described camera 10 includes a four πήrror folded optical path for the telephoto optical system which has a portion thereof that wraps around the film plane 48 so that two mhrors 110 and 116 and the principal optical path segment 114 therebetween are aD behind or to the rear ofthe fihn plane 48, these three ahemative preferred embodiment cameras 210, 310 and 410 differ from camera 10 in that they have all the wide angle and telephoto lens elements, the four mirrors in the telephoto optical system and the corresponding principal optical path segments therebetween, in from ofthe film plane 48. These three cameras retain the desired compactness characteristic but have external camera shapes whh differ from camera 10, and each other , as wiU become apparent , because they each employ different four mirror optical path foMing configurations.

Where practical, camera components that are similar to those in camera 10 and have essentiaUy the same function wiD be numbered the same in the drawings but wiD include a prefix digh of 2, 3 or 4 , respectively for the ahemative preferred embodiment cameras 210, 310 and 410. For example, the camera 10 primary or wide angle taking lens 36 shaU be designated 236 for camera 21 Q, 336 for camera 310 and 436 for camera 410.

As shown in Figs. 13 and 13a, camera 210 includes a box like camera housing 212 having a forward wall 214 and opposed rear or back wafl 216 having structure on the interior surface thereof defining a film plane 248. Projecting forwardly of wafl 214 in a lens housing (not shown) is a wide angle, or primary, taking lens 236 positioned whh hs optic axis 352 normal or perpendicular to the film plane 248 for focusing an image of an object or subject on a segment of photographic film strip located at film plane 248.

Also projecting forwardly of forward housing wall 214 and downwardly below housing bottom wall 220 is a telephoto optical system, enclosed in a housing (not shown), including a medium telephoto lens 2100 and four rnirrors 2110, 21162122 and 290 for defining a compact folded optical path between lens 2100 and the film plan 248. As in the previously described camera 10, the first three mirrors 2110, 2116 and 2122 are fixed in then illustrated positions, but the fourth rnirror 290 is mounted for movement between a first position (not shown) where h has been pivoted counter-clockwise, as viewed in Fig. 13a, about h forward lower edge out ofthe field of wide angle lens 236 in which h r^πn s scene light emerging from the wide angle lens system to impinge on fi plane 248 while preventing scene light from emerging from said telephoto lens system from impinging on the fihn plane 248 and a second position, best shown in Fig. 13a, in which h prevents scene light emerging from the wide angle optical system from impinging on said film plane 248 while directing scene Hght emerging from said telephoto optical system onto film plane 248. Camera 210 differs from camera 10 in that h has all of hs wide angle and telephoto lens elements and the four mirrors in the telephoto optical system along whh the corresponding principal optical path segments therebetween in front ofthe film plane 248. In this embodiment, the wide angle lens 236 and the medium telephoto lens 2100 are mounted such that their respective optical axes are paraDel to each other and are normal or orthogonal to the film plane 248.

With reference to Fig. 14, camera 310 is similar to camera 210 in most respects, but h has hs telephoto optical system rotated 90° in a counter-clockwise direction whh respect to the telephoto system of camera 210 when looking at the front elevational view of these two camera in Figs 13 and 14a. The advantage of this configuration is that the height ofthe camera 310 does not have to be increased to accommodate the medium telephoto optical system.

As shown in Figs. 14, 14a 14b and 14c, camera 310 includes a box like camera housing 312 having a forward waD 314 and opposed rear or back waD 316 having structure on the interior surface thereof defining a film plane 348. Projecting forwardly of wall 314 in a lens housing (not shown) is a wide angle, or primary, taking lens 336 positioned whh hs optic axis 352 normal or perpendicular to the film plane 348 for focusing an image of an object or subject on a segment of photographic film strip location at film plane 348. Also projecting forwardly of forward housing wall 314 and laterally beyond housing side waD 322 is a telephoto optical system, enclosed in a housing (not shown), including a medium telephoto lens 3100 and four mirrors 3110, 3116, 3122 and 390 for defining a compact folded optical path between lens 3100 and the fihn plan 348. As in the previously described camera 10, the first three mirrors 3110, 3116 and 3122 are fixed in their iDustrated positions, but the fourth mirror 390 is mounted for movement between hs first position (not shown) where h has been pivoted counter-clockwise about its forward lower edge, out ofthe field of wide angle lens 336, in which it permhs scene fight emerging from the wide angle lens system to impinge on said film plane 348 while preventing scene light from emerging from said telephoto lens system from impinging on the film plane 348 and second position, best shown in fig. 14c, in which h prevems scene light emerging from the wide angle optical system from impinging on said film plane 348 while directing scene light emerging from said telephoto optical system onto fihn plane 348.

Camera 310 differs from camera 10 in that it has aD ofhs wide angle and telephoto lens elemems and the four mirrors in the telephoto optical system, along whh the corresponding principal optical path segments therebetween, in front ofthe film plane348. In this embodiment, the wide angle lens 336 and the medium telephoto lens 3100 are mounted such that their respective optical axes are parallel to each other and are normal or orthogonal to the film plane 348. Whh reference to Figs. 15, 15a and 15b, a camera 410 has aD of hs wide angle and telephoto lens elemems and the four mirrors in the telephoto optical system, and the corresponding principal optical path segments therebetween, in front of the film plane just like configurations of camera 210 and 310, but h differs significantly from the optical configurations of camera 10 , 210 and 310 in that hs medium telephoto lens 4100 is mounted so that its optical axis 4108 is orthogonal to the optical axis 452 ofthe wide angle lens 436 and paraJlel to the fihn exposure plane 448.

Camera 410 includes a box like camera housing 412 having a forward waD 414 and opposed rear or back waD 416 having stracture on the interior surface thereof defining a fihn plane 448. Projecting forwardly of wall 414 in a lens housing (not shown) is a wide angle, or primary, taking lens 436 positioned whh hs optical axis 452 normal or perpendicular to the fihn plane 448 for focusing an image of an object or subject on a segment of photographic film strip location at fihn plane 448.

Projecting upwardly from housing top waD 18 is a housing (not shown) enclosing the medium telephoto lens 4100 and the first two mirrors 4110 and 4116 ofthe camera's four mirrors in the camera's four mirror telephoto system. The first mirror 4110 extends upwardly from top waD 418 whh hs leading edge near forward waD 414 and is angled whh respect to the optical axis 4108 of telephoto lens 4100 to reflect image bearing light rearwardly to the second mirror 4116. Mirror 4116 extends upwardly from top waD 418 and is angled to reflect fight from mirror 4110 forwardly, parallel to top waD 418, past housing forward waD 414 into a mirror housing (not shown) projecting forwardly of housmg waD 414 and mounting the third and fourth rnirrors 4122 and 490 therein. Mirror 4122 is angled downwardly at 45° and folds the light from mirror 4116 through 90 to rnirror 490 which is mounted at an angle of 45° whh respect to housing wafl 414 to fold the light from mirror 4122 through 90° readwardly to the fihn plane 448 to expose a segment of a film strip located there. As in the previously described camera 10, the first three mirrors 4110, 4116 and 4122 are fixed in their iDustrated positions, but the fourth rnirror 490 is mounted for movement between hs first position (not shown) where h has been pivoted clockwise about h forward upper edge, out ofthe field of wide angle lens 436, in which h r>eπmts scene light emerging from the wide angle lens system to impinge on the film plane 448, while preventing scene light from emerging from the telephoto lens system from impinging on the film plane 448 and a second position, best shown in Fig 15a, in which h prevents scene light emerging from the wide angle optical system from impinging on said fihn plane 448, while directing scene Hght emerging from said telephoto optical system onto fihn plane 448. In another comparison ofthe four d fferent preferred ernbodimeπts ofthe compact, dual focal length cameras disclose herein, it will be apparent to one skiDed in the art that due to the various arrangements ofthe four mirrors in the telephoto systems, cameras 210, 310 and 410 wiD produce telephoto images on the film that are rotated (upside down and backward) relative to the wide angle images. Thus, when a camera user receives prints from these cameras 210, 310, and 410, he or she wiD be able to readfly separate the telephoto from the wide angle photographs based on whether he or she has to rotate to the proper orientation for viewing.

Another embodiment ofthe present invention that is not a dual focal length camera is shown in Fig. 16. Here, a telephoto camera, that is suitable as a single-use camera, is shown designated at 500. Camera 500 is si ilar in many ways to the dual focal length camera of Figs. 3 and 4, but is much less complex because h has only one objective taking lens system,and therefore ,does not require a moveable mirror or twin viewfinders as were needed whh the previously described dual focal length cameras in converting between their wide angle to telephoto modesof operation

As seen in Fig. 16, camera 500 comprises a telephoto objective taking lens system 502 of two-element design having a first lens 504 foDowed by a second lens 506. Lens 504 and 506 may possess the constructional features of similar telephoto systems previously described in the above tables relating to telephoto designs. FoDowing lens 506 are four mhrors, 508, 510, 512, and 514 for folding the telephoto taking path four times, as before, to direct image bearing rays to the film plane designated here as 516.

A shutter shown at 518 pivots about a point of rotation 520 to provide exposure control in a as before or in weϋ-known manners suitable for single talcing lens cameras. Camera 500 whh its telephoto optical path wrapped around film plane 516 thus represents a compact camera capable of taking telephoto pictures with lens focal lengths in the middle ofthe telephoto range. As such, h is an attractive companion for use with low-cost binoculars in taking photographs that mimic what users see in the binoculars, but without the complexity and cost associated whh the dual focal length versions previously described. As wiD be readily apparent, the non-dual focal length telephoto camera described above may also have the folded optical path configurations described in connection whh Figs. 13 through 15 whh the wide angle lens removed.

Other variations ofthe invention wiD be obvious to those slriDed in the art who may make changes whhout departing from the scope of its teachings. It will be readily apparent, for example, that where film is the photodetector, the film plane may be curved in one a^yήrmth and popular fihn formats other than the 35mm and APS formats may be used. Where formats other than 35mm are to used, the focal lengths may be scaled to appropriate wide angle and telephoto values. In addition, more complex optical systems may be used for both wide angle and telephoto systems. For example, the wide angle systems could easily be of two or more element construction. In the case where a curved film plane is used, h preferably has a cylindrical radius of 200 m Therefore, h is intended that the embodiments shown herein be considered iDustrative and not in a limhmg sense.

Claims

What is claimed is:

1. A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close-up photographs that have the appearance of distant scenes as observed through binoculars, said camera comprising: a compact housing: means for defining a film plane within said housing; a wide angle lens system for forming a wide angle image of a scene at said film plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing imaging bearing light along a first optical path to said film plane for use in the wide angle mode of operation; a telephoto lens system for forming a magnified image of a scene at said film plane, said telephoto lens system including a telephoto lens, having a focal length that is at least three times longer than said given focal length of said wide angle lens; four mirrors for providing a folded optical path between said telephoto lens system and said fihn plane, at least one of said four m rors being mounted for movement between a first position in which it permits scene Hght emerging from said wide angle lens system to impinge on said film plane while preventing scene Hght from emerging from said telephoto lens system from impinging on said film plane and a second position in which h prevems scene Hght emerging from said wide angle optical system from πnpinging on said film plane while directing scene Hght emerging from said telephoto optical system onto said film plane; and means for moving said moveable mirror between hs said first and second positions.

2. The camera of claim 1 wherein the entrances to both of said lens systems He substantially in the plane.

3. The camera of claim 1 further including a single shutter which is operable for managing the transmission of image bearing Hght through both said wide angle and telephoto lens systems.

4. The camera of claim 3 wherein said single shutter operates at a predeteπnined fixed angular velochy for both said wide angle and telephoto modes of operation.

5. The camera of claim 4 wherein said wide angle lens systems includes a wide angle lens and a corresponding wide angle aperture having a first size, said telephoto lens system includes a medium telephoto lens and a corresponding telephoto aperture having a second size and said first and second aperture sizes are such that, upon operation of said shutter at said fixed angular velochy, a film unh in said film plane is subjected to substantiaDy the same exposure to image bearing Hght during both the wide angle and telephoto modes of operation.

6. The camera of claim 5 wherein said shutter velocity and said wide angle and telephoto lens systems are configured to expose photographic film having a film speed in the range of 700- 1600 ASA.

7. The camera of claim 1 wherein said wide angle lens is a singlet and said telephoto lens is formed of two-elements.

8. The camera of claim 1 wherein at least a portion of said folded optical path between said folded telephoto lens system and said fihn plane wraps around said film plane.

9. The camera of claim 8 wherein said wide angle and telephoto lens systems and two of said four mirrors are located in front of said film plane and the other two of said four mirrors are located behind said film plane to define said portion of said folded optical path that wraps around said film plane.

10. The camera of claim 1 wherein said wide angle and telephoto lens systems and said four rnirror are afl located on the same side of said film plane.

11. A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close up photographs, said camera comprising: a compact housing; means for defining a fihn plane within said housing; a wide angle lens system for forming a wide angle image of a scene at said film plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing image bearing Hght along a first optical path to said fihn plane for use in the wide angle mode of operation; a telephoto lens system for forming a magnified image of a scene at said film plane, said telephoto lens system including a medium telephoto lens; four mhrors for providing a folded optical path between said telephoto lens system and said film plane, said four mhrors being arranged such that at least a portion of said folded optical path wraps around said film plane, at least one of said four mirrors being mounted for movement between a first position in which h permits scene light emerging from said wide angle lens system to impinge on said fihn plane while preventing scene Hght from emerging from said telephoto lens system from impinging on said film plane and a second position in which h prevents scene Hght emerging from said wide angle optical system from impinging on said film plane while directing scene Kght emerging from said telephoto optical system onto said film plane; and. means for moving said moveable mirror between its said first and second positions.

12. The camera of claim 11 wherein said wide angle and telephoto lens systems and two of said four mirrors are located in from of said film plane and the other two of said four mhrors are located behind said film plane to define said portion of said folded optical path that wraps around said film plane.

13. The camera of Claim 11 wherein said medium telephoto lens has a focal length that is at least three times longer than said given focal length of said wide angle lens.

14. The camera of claim 11 wherein said wide angle lens is a singlet and said telephoto lens is formed of two elements.

15. The camera of claim 11 wherein said wide angle lens is a singlet and said telephoto lens is a doublet.

16. A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close up photographs, said camera comprising: a compact housing: means for defining a fihn plane whhin said housing for supporting a fihn having a film format of a given height; a wide angle lens system for forming a wide angle image of a scene at said film plane, said wide angle lens system mchiding a wide angle lens, having a given focal length, for directing image bearing Hght along a first optical path to said film plane for use in the wide angle mode of operation; a telephoto lens system for forming a magnified image of a scene at said film plane, said telephoto lens system including a telephoto lens, having a focal length that is at least three times longer than said given focal length of said wide angle lens; and four rnirrors for providing a folded optical path between said telephoto lens system and said film plane; wherein the size ofthe camera and the optical path length available for the telephoto design are related to the height ofthe fihn format and the focal length ofthe wide angle or primary lens focal length as foDows: TFPL(telephoto path length) = 2 (H_f+ EFF_*.),

where H_f is the height ofthe film format and EFF„_» is the effective focal length ofthe wide angle design.

17. A compact, dual focal length imagmg system operable in a wide angle mode and a telephoto mode, said imaging system comprising: a compact housing: means for defining a photodetector plane whhin said housing; a wide angle lens system for forming a wide angle image of a scene at said photodetector plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing image bearing Hght along a first optical path to said photodetector plane for use in the wide angle mode of operation; a telephoto lens system for forming a magnified image of a scene at said photodetector plane, said telephoto lens system including a telephoto lens, having a focal length that is at least three times longer than said given focal length of said wide angle lens; four mirrors for providing a folded optical path between said telephoto lens system and said photodetector plane, at least one of said four mirrors being mounted for movement between a first position in which h permits scene fight emerging from said wide angle lens system to impinge on said photodetector plane while preventing scene Hght from emerging from said telephoto lens system from impinging on said photodetector plane and a second position in which h prevents scene Hght emerging from said wide angle optical system from impinging on said photodetector plane while directing scene Hght emerging from said telephoto optical system onto said photodetector plane; and means for moving said moveable mirror between hs said first and second positions.

18. The system of claim 17 further including a photodetector array mounted in said photodetector plane.

19. A compact telephoto camera for taking close-up photographs that have the appearance of distant scenes as observed through binoculars, said camera comprising: a compact housing: means for defining a film plane within said housing; a telephoto lens system having an optical path for forming a magnified image of a scene at said film plane, said telephoto lens system comprising two lens elements which in combination have a focal length in the medium telephoto range, and four mirrors for folding the optical path of said telephoto lens system to said film plane.

20. The camera of claim 19 wherein said telephoto lens system is further configured to expose photographic film having a film speed in the range of 700- 1600 ASA.

21. The camera of claim 19 wherein at least a portion of said folded optical path between said folded telephoto lens system and said film plane wraps around said film plane.

22. The camera of claim 19 wherein said telephoto lens system and two of said four mirrors are located in front of said film plane and the other two of said four mirrors are located behind said film plane to define said portion of said folded optical path that wraps around said film plane.

23. The camera of claim 19 wherein said telephoto lens system and said four mirror are aD located on the same side of said film plane.

24. The camera of claim 19 where said medium telephoto range encompasses telephoto lens systems having focal lengths in the range between 120 and 240mm.

25. A compact, telephoto imaging system, said imaging system comnrising: a compact housing; means for defining a photodetector plane whhin said housing; a medium focal length telephoto lens system having an optical path for forming a magnified image of a scene at said photodetector plane, said telephoto lens system comprising two lens elements; and four rnirrors for folding said optical path to said photodetector plane.

26. The system of claim 25 further including a photodetector array mounted in said photodetector plane.

AMENDED CLAIMS

[received by the International Bureau on 3 August 1998 (03.08.98) original claims 1-26 replaced by new claims 1-35 (10 pages)]

1 A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close-up photographs that have the appearance of distant scenes as observed through binoculars, said camera comprising a compact housing having a forward housing wall, means for defining a film plane within said housing; a wide angle smglet lens for forming a w de angle image of a scene at said film plane, said wide angle smglet lens being located within said compact housing and having a given focal length for directing imagmg bearing light along a first optical path to said film plane for use in the wide angle mode of operation; a telephoto lens system also located within said compact housmg for forming a magnified image of a scene at said film plane, said telephoto lens system including a telephoto lens having too- elements and a focal length that is at least three times longer than said given focal length of said wide angle lens; four mirrors for providing a folded optical path between said telephoto lens system and said film plane, at least one of said four mirrors bemg mounted for movement between a first position in which scene light emerging from said wide angle smglet lens impinges on said Film plane while preventmg scene light emerging from said telephoto lens system is prevented from impinging on said film plane and second position which scene light emerging from said wide angle smglet lens is prevented from impinging on said film plane while scene light emerging from said telephoto optical system is directed onto said film plane, and means for moving said moveable mirror between said moveable mirror's said first and second positions

2. The camera of claim 1 wherein the entrances to both said wide angle singlet lens and said telephoto lens system are formed in said forward housing wall of said compact housing.

3. The camera of claim 1 further including a single rotating blade shutter which is operable for managing the transmission of image bearing light through both said wide angle singlet lens and said telephoto lens system.

4. The camera of claim 3 wherein said single rotating blade shutter operates at a predetermined fixed angular velocity for both said wide angle and telephoto modes of operation.

5. The camera of claim 4 wherein said wide angle singlet lens has a corresponding wide angle aperture having a first size, said telephoto lens system includes a medium telephoto lens and a corresponding telephoto aperture having a second size and said first and second aperture sizes are such that, upon operation of said shutter at said fixed angular velocity, a film unit in said film plane is subjected to substantially the same exposure to image bearing light during both the wide angle and telephoto modes of operation.

6. The camera of claim 5 wherein said shutter velocity and said wide angle singlet lens and said telephoto. lens system are configured to expose photographic film having a film speed in the range of 700-1600 ASA.

8. The camera of claim 1 wherein at least a portion of said folded optical path between said folded telephoto lens system and said film plane wraps around said film plane.

9. The camera of claim 8 wherein said wide angle singlet lens and said telephoto lens system and two of said four mirrors arc located in front of said film plane and the other two of said four mirrors are located behind said film plane to define said portion of said folded opucal path that wraps around said film plane.

11. A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close up photographs, said camera comprising: a compact housing; means for defining a film plane within said housmg; a wide angle lens system located within said housmg for forming a wide angle image of a scene at said film plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing image bearing light along a first optical path to said film plane for use in the wide angle mode of operation; a telephoto lens system located within said housing for forming a magnified image of a scene at said film plane; four mirrors for providing a folded optical path between said telephoto lens system and said film plane, said four mirrors bemg arranged such that at least a portion of said folded optical path wraps around said film plane, at least one of said four mirrors bemg mounted for movement between a first position in which scene light emerging from said wide angle lens system impinges on said film plane while scene light emerging from said telephoto lens system is prevented from impinging on said film plane and a second position in which scene light emerging from said wide angle optical system is prevented from impinging on said film plane while scene light emerging from said telephoto optical system is directed onto said film plane;

-43-

ΛMENDED SHEET (ARTICLE 19) and means for moving said moveable mirror between said moveable mirror's said first and second positions.

12. The camera of claim 11 wherein said wide angle and telephoto lens systems and two of said four mirrors are located in front of said film plane and the o er two of said four mirrors are located behind said fihn plane to define said portion of said folded optical path that wraps around said film plane.

16. A compact, dual focal length camera operable in a wide angle mode for taking wide angle photographs and a telephoto mode for taking close up photographs, said camera comprising: . a compact housing; means for defining a film plane within said housing for supporting a film having a film format of a given height; a wide angle lens system located within said compact housing for forming a wide angle image of a scene at said film plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing image bearing light along a first optical path to said film plane for use in the wide angle mode of operation; a telephoto lens system located within said compact housing for forming a magnified image of a scene at said film plane, said telephoto lens system including a telephoto lens having a focal length that is at least three times longer than said given focal length of said wide angle lens; and four mirrors for providing a folded optical path between said telephoto lens system and said film plane; wherein the size of the camera and the optical path length available for the telephoto design are related to the height of the film format and the focal lengtfi of the wide angle or primary lens focal length as follows:

TFPL (telephoto path length) = 2(H_f + EFF_wa), where H_r is the height of the film format and EFF_wa is the effective focal length of the wide angle design.

17. A compact, dual focal length imaging system operable in a wide angle mode and a telephoto mode, said imaging system comprising: a compact housing; means for defining a photodetector plane within said housing; an imaging photodetector array located in said photodetector plane; a wide angle lens system located within said compact housing for forming a wide angle image of a scene at said photodetector plane, said wide angle lens system including a wide angle lens, having a given focal length, for directing image bearing light along a first optical path to said photodetector plane for use in the wide angle mode of operation; a telephoto lens system located within said compact housing for forming a magnified image of a scene at said photodetector plane, said telephoto lens system including a telephoto lens, having a focal length that is at least three times longer than said given focal length of said wide angle lens;

four mirrors for providing a folded optical pau between said telephoto lens system and said photodetector plane, at least one of said four mirrors being mounted for movement between a first position in which scene light emerging from said wide angle lens system impinges on said photodetector plane while scene light emerging from said telephoto lens system is prevented from impinging on said photodetector plane while scene light emerging from said telephoto optical system is directed onto said photodetector plane; and means for moving said moveable mirror between said moveable mirror's said first and second positions.

19. A compact telephoto camera for taking close-up photographs that have the appearance of distant scenes as observed through binoculars, said camera comprising: a compact housing; means for defining a film plane within said housing; a telephoto lens system located wiu in said housing and having an optical pam for forming a magnified image of a scene at said fihn plane, said telephoto lens system comprising two lens elements which in combination have a focal length in the medium telephoto range, and four miπrors for folding the optical path of said telephoto lens system to said film plane.

20. The camera of claim 19 wherein said telephoto lens system is further configured to expose photographic film having a fihn speed in the range of 700-1600 ASA.

21. The camera of claim 19 wherein at least a portion of said folded optical path between said folded telephoto lens system and said film plane wraps around said film plane,

22, The camera of claim 19 wherein said telephoto lens sysiem and two of said four mirrors are located in front of said film plane and the otiier two of said four mirrors are located behind said film plane to define said portion of said folded optical path that wraps around said film plane.

25. A compact, telephoto imaging system, said imaging system comprising: a compact housing; means for defining a photodetector plane within said housing; a photodetector array mounted in said photodetector plane; a medium focal length telephoto lens system having an optical path for forming a magnified image of a scene at said photodetector plane, said telephoto lens system comprising two lens elements; and four mirrors for folding said optical path to said photodetector plane.

27. A compact camera for taking close-up photographs that have the appearance of distant scenes as observed through binoculars, said camera comprising: a compact housing; means for defining a film plane within said housing; an objective lens system witfiin said housmg having an optical path for foπning a magnified image of a scene at said film plane, said optical path comprising four mirrors for folding said optical paύ between said objective lens system and said film plane, wherein at least a portion of said optical path wraps around said film plane.

28. The camera of claim 27 wherein said objective lens system and two of said four mirrors are located in front of said film plane and the other two of said four mirrors are located behind said film plane to define said portion of said optical path ύat wraps around said film plane.

29. The camera of claim 27 where said objective lens system has a focal length in the range including 120 to 240 mm.

30. A compact, imaging system, said imaging system comprismg: a compact housing; means for defining a photodetector plane within said housing; an objective lens system within_, said housing having an optical paui for forming a magnified image of a scene at said photodetector plane, said optical path comprising four mirrors for folding said optical path between said objective lens system and said photodetector plane, wherein at least a portion of said optical path wraps around said photodetector plane.

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ΛMENDED SHEET (ARTICLE 19⁾

31. The camera of claim 30 wherein said objective lens system and two of said four mirrors are located in front of said photodetector plane and the other two of said four mirrors are located behind said photodetector plane to define said portion of said folded optical path that wraps around said photodetector plane.

32. The compact, dual focal length camera of claim 11 wherein said telephoto lens is of medium focal length.

33. The compact, dual focal length camera of claim 11 wherein said four mirrors include a first mirror located behind said film plane for intercepting light from said telephoto lens and directing it along a first branch of said folded optical path that is substantially parallel to said film plane, a second mirror for intercepting light traveling along said first branch and directing it for travel along a second branch of said folded optical path toward object space, a third mirror for intercepting light traveling along said second branch and directing it for travel along a third branch of said folded optical path that ends wirh said mirror mounted for movement, said mirror mounted for movement directing light along a fourth branch of said folded optical path that terminates on said film plane

34. The compact camera of claim 27 wherein said objective lens system comprises a telephoto lens system of medium focal length.

35. The compact, dual focal length camera of claim 11 wherein said four mirrors include a first mirror located behind said film plane for intercepting light from said telephoto lens and directing it along a first branch of said folded optical path that is substantially parallel to said film

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ΛMENDED SHEET (ARTICLE 19) lane, a second rnirror for intercepting light traveling along said first branch and directing it for travel along a second branch of said folded optical path toward object space, a third mirror for intercepting light traveling along said second branch and directing it for travel along a third branch of said folded optical path that ends with said mirror mounted for movement, said πύrror mounted for movement directing light along a fourth branch of said folded Optical path that terminates on said film plane.