Camera Body for Use with an Interchangeable Lens Unit

Abstract: A lens accormmadation device for a camera comprising a camera body and a lens unit interchangeably mounted to the camera body. The lens unit is provided with means for providing data to the camera body, the data representing whether a photographic lens thereof is accommodatable. The device comprises means for driving the photographic lens of the lens unit in a direction in which the photographic lens is accommodated under a predetermined condition in case the photographic lens of the lens unit mounted to the camera body is accomodatable one.

Description: The present invention relates to a camera body according to claim 1 and to a camera system according to claim 5. Some of so-called compact cameras unable to exchange a photographic lens employ such a system that a lens group is automatically accommodated when the camera is not in use to reduce the projecting length of the lens group and to facilitate the portability of the camera. Such a lens accommodation system is not employed in cameras of the kind described in EP-A-0 262 679 and having an interchangeable lens. First, whereas a lens shutter zoom camera employs a single lens, an SLR camera uses a plurality of lenses, some of which may be zoom lenses with driving means and some of which may have a fixed focal length. Furthermore, some type of zoom lenses, such as a vari-focal type zoom lenses, have an overall length that does not change as the focal length of the lens is changed. In addition, even if the overall length of the lens changes as the focal length of the lens is changed, the amount of the length change varies from lens type to lens type. Thus, in order to prevent possible damage to a lens accommodation system, the SLR camera body would need to know via data receiving means by data received from the lens whether the lens attached to the camera body can be accommodated, and if it can be accommodated, when to terminate the lens retracting operation. This is not provided in a camera described in EP-A-0 262 679. The techniques used to accommodate a lens on a lens shutter camera have not been applied to cameras employing interchangeable lenses. It is therefore the problem to be solved by the invention to provide a lens accommodation device suitably applicable to a camera capable of exchanging a photographic lens which is capable of automatically accommodating a lens group to decrease the size thereof to facilitate the portability of the camera when it is not used. For the above purpose, according to this invention, there is provided a camera body and a camera system having the features of claim 1 and claim 5, respectively. According to the invention each photographing lens exchangeably mounted on the camera body is provided with data indicating whether it can be accommodated or not as its inherent data. Therefore, the camera body is not required to be provided with data indicating whether various kinds of photographing lenses can be accommodated or not. As a result, the amount of data to be stored in the camera body can be reduced, and thus a camera lens accommodating device can be arranged as a relatively simple processing system so that this system is preferable for cameras provided with various kinds of exchangeable photographing lenses. The invention will now be further described with reference to the drawings in which Fig. 1 is a block diagram illustrative of an overall camera system; Fig. 2 is a circuit diagram in a camera body; Fig. 3 is a circuit diagram in a photographic lens; Figs. 4 and 5 are main flowcharts regarding the accommodation of a lens in this system; Fig. 6 is a subroutine to stop the AF drive of a focusing lens; and Fig. 7 is a subroutine to stop the drive of a zooming lens. Although the embodiment will be described with reference to an automatic single lens reflex camera shown in the drawings, it is also applicable to a still video camera and the like. A camera body CB is interchangeably provided with various photographing lenses mounted thereon by a known arrangement as shown in the drawings. Fig. 1 is a block diagram of a combined system of a photographic lens L and a camera body CB embodying invention. The camera body CB is provided with two CPUs, a main CPU 10 used to process various kinds of data for photographing and a display CPU 11 used to input data, supply and receive data to and from the photographic lens L, and display information mainly through a switch. The camera body CB is provided with an LCD panel 12 for displaying various kinds of information, a DX code input circuit 13 for inputting an ISO (International Standard Organization) sensitivity of a film from a DX code printed on a film cartridge, a light receiving element 14 for measuring the luminance of an object to be photographed from light incident through the photographic lens L, an A/D (Analog/Digital) converter 15 for effecting an analog to digital conversion of an output from the light receiving element, an exposure control circuit 16 for controlling a shutter based on various input photographing conditions, a CCD 17 for automatic focusing (AF) for receiving light from the image of the object to be photographed which is formed by the light incident through the photographing lens L, and a CCD processing circuit 18 for detecting a focusing state of the photographing lens L based on an output from the CCD 17 for AF (Automatic Focusing), together with the CPUs as central units. Further, when a conventional type photographic lens L not having an AF motor therein is mounted, an AF motor 19 for focusing the photographic lens is used to transmit a driving force to the photographic lens L side through a coupler 19a attached to a mounting port. An AF motor control circuit 20 drives the AF motor 19 by calculating an output from the CCD processing circuit 18, and an AF pulser 21 for detects a driving amount of the AF motor 19 as a number of pulses. The AF motor 19 is not used in the case shown in Fig. 1. A battery 22 supplies power to the respective active elements in the above camera body CB as well as to the motors in the photographic lens L to be described later and to the CPUs. On the other hand, the photographic lens L contains three motors therein, an AF motor 60, a power zoom (PZ) motor 61 and an automatic aperture control (AE) motor 62 so that automatic focusing, power zooming and aperture control can be carried out by driving-forces in the lens unit L. Note that the photographic lens L has cam mechanisms like conventional ones which effect focusing and zooming by relatively moving each lens group in the optical axis direction by the rotation of cam rings, and the above AF motor 60 and the PZ motor 61 are used to rotate the cam rings. The respective motors are controlled by a lens CPU 66 as a calculation means through an AF motor drive unit 63, a PZ motor drive unit 64 and an AE motor drive unit 65. A data input means for the lens CPU 66 includes a lens ROM 67 for storing data inherent to the photographic lens, an AF pulser 68 for detecting a drive amount of each motor by converting the amount to a number of pulses, a PZ pulser 69, an AE pulser 70, a zoom code plate 71 and a distance code plate 72 for detecting rotational positions of the zooming cam ring and the focusing cam ring, respectively. Note that in practical use the code plate comprises a combination of a code plate fixed to the cam ring and a plurality of brushes attached to a fixed ring and in sliding contact with the code plate so that an absolute rotational position of the ring is detected by the contact states of the brushes. However, the term "code plate" used here conveniently means the above members as a whole. The lens CPU 66 can communicate with the camera body CB through electrical contacts TC to be described below in addition to being coupled with the above control subjects and the input means. For example, the CPU 66 has a function for driving the AF motor 60 by calculating a driving amount thereof based on a defocus amount detected on the camera body CB side while referring to data of the lens ROM 67 and detecting a driven amount of the motor by the AF pulser 68, a function for driving the AE motor 62 based on an aperture value determined on the camera body CB side while detecting a driven amount thereof by the AE pulser 70 and the like. A lens mount of the camera body CB is provided with an electrical contact group T1 composed of ten electrical contacts insulated from the surface of the camera body mounting ring. On the other hand, the mount portion of the photographic lens L is provided with an electrical contact group T2 corresponding to the electrical contact group T1 provided on the camera body CB. When the photographic lens L is mounted on the camera body CB, each contact of the electrical contact group T1 is brought into contact with a corresponding contact of the electrical contact group T2 having the same references as that of the group T1 to form the above electrical contact group TC. This system will be described below with reference to detailed circuit diagrams. Fig. 2 is a circuit of the camera body CB. The display CPU 11 has a V DD 1 terminal supplied with a voltage from the battery 22 after it is subjected to a voltage transformation by a regulator R and backed up by a super capacitor 24, and it is operated at a constant voltage at all times. In addition, the display CPU 11 has a P1 terminal coupled with a DC/DC converter 25 for turning ON/OFF a power supply to the main CPU 10 and a P2 terminal coupled with a light measuring switch SW S which is turned ON by depressing a shutter button to a first stage. A P3 terminal is coupled with a release switch SW R which is turned ON by depressing the shutter button to a second stage, and a P4 terminal is coupled with a lock switch SW L which is turned ON when the camera is enabled to take a photograph. Data from the respective switches are input. The lock switch SW L serves as a main switch in this invention and is mounted on the camera body CB. The DC/DC converter 25 supplies power to the V DD terminal of the CPU 10 when the light measuring switch SW S is turned ON and when the lock switch SW L is turned ON. Further, a P5 terminal is coupled with a mode switch SW M which is turned ON to select photographing modes such as a programmed photographing mode, an automatic photographing mode, a manual photographing mode and the like. A P6 terminal is coupled with a drive switch SW DR which is turned ON to select a single-shot photographing mode, a sequential-shots photographing mode or the like, and a P7 terminal is coupled with an exposure correction switch SW XV which is turned ON to enable a set exposure to be corrected. Respective set states can be changed by operating an up-count switch SW UP coupled with a P8 terminal or a down-count switch SW DN coupled with a P9 terminal when the switches coupled with these terminals P5 to P7 are turned ON, respectively. A P SEG terminal group is used to operate the LCD panel 12 which displays stored information when the lock switch SW L is turned ON. The main CPU 10 has a PA contact group coupled with the A/D converter 15 for measuring light, a contact group PB coupled with the exposure circuit 16, a PC contact group coupled with the CCD processing circuit 18, a PD contact group coupled with the AF motor control circuit 20, a PE contact group coupled with the AF pulser 21, and a PF contact group coupled with the DX input circuit 13. Note that the A/D converter 15 is coupled with the light receiving element 14 for measuring light, the CCD processing circuit 18 is coupled with the CCD 17 for AF (Automatic Focusing), and the AF motor control circuit 20 is coupled with the AF motor 19 in the camera body CB, as described above. Further, the main CPU 10 has a P20 terminal coupled with a first automatic focusing switch SW AF 1 for changing focusing between an automatic mode effected by driving the AF motor and a manual mode effected by a manual drive by a user, and a P21 terminal coupled with a second automatic focusing switch SW AF 2 for changing a shutter release mode between focus-priority mode and shutter-priority mode. Fig. 3 shows a circuit of the photographic lens L. A contact V BATT on the lens unit side is coupled with the respective motor drive units 63, 64 and 65 in the lens unit and the battery 22 in the camera body CB supplies power directly to the respective motors 60, 61 and 62 when these drive units are switched on. Note that the respective motor drive units 63, 64 and 65 are controlled by the lens CPU 66 by being coupled with the P H , P I and P J terminal groups thereof, and the pulsers 68, 69 and 70 are coupled with terminal P20 to P22 to input the detected driven amounts of the respective motors to the lens CPU 66. A contact V DD supplied from the display CPU 11 of the camera body CB side is coupled with a V DD terminal of the lens CPU 66 and with a reset circuit composed of a resistor R, a diode D and a capacitor C. A prescribed time constant is given to the reset circuit by the resistor R and the capacitor C so that the reset circuit has a function to change a RESET terminal from an active (L) state to a non-active (H) state to enable the program of the CPU 66 to start when a prescribed period of time elapses after the power is supplied to the V DD and the voltage of the power is stabilized. The lens CPU 66 has P23 to P27 terminals respectively coupled with a third automatic focusing switch SW AF 3 disposed on the lens unit side for changing between an automatic focusing and a manual focusing, a zoom changing switch SW PZ 1 for selecting whether zooming is to be automatically effected by the motor or to be manually effected, a constant image magnification switch SW PZ 2 for automatically effecting zooming when the camera moves with respect to an object to be photographed to maintain a given image magnification of the object, a tele side zoom switch SW PZT for driving a PZ motor 61 to move the photographic lens L in a direction to increase the focusing distance thereof, and a wide side zoom switch SW PZW for driving the PZ motor to move the photographic lens L in a direction to decrease the focusing distance thereof. The lens CPU 66 is provided with an INT terminal to which an electric signal is supplied to interrupt the execution of the program of the CPU 66, a SCK terminal to which a serial clock is supplied from the display CPU 11 on the camera body CB side, an SI/SO terminal for serially transmitting data, and an RDY terminal for synchronizing a serial communication of the CPU 66 with a peripheral unit. After RESET , th voltage at the INT terminal is changed from a low value to a high value to enable the interruption to the lens CPU 66, and the voltage at the RDY terminal is changed to a high value to cause the display CPU 11 on the camera body CB side to wait to inhibit the execution of a serial communication, and is changed to a low value to enable the execution of the serial communication. Further, a P K terminal group of the lens CPU 66 is coupled with the code plate 71 and the distance plate 72 like the terminal groups P L and P M of the lens ROM 67 so that focusing data and distance data corresponding to an actual lens state are input. The lens ROM 67 stores the inherent data of the photographic lens L, for example fixed data such as a open-aperture F number, a minimum-aperature F number, an amount of change of the F number caused by zooming, and variable data. In particular with this embodiment the lens ROM 67 stores as the inherent data of the photographing lens data regarding the accommodation of the lens such as whether the photographic lens L is arranged to have the total length thereof expandable or contractible when each lens group is driven by the AF motor 60 or the PZ motor 61 of the photographic lens L (in this specification, this is referred to as "accommdation is possible"). Note that the data regarding whether the photographic lens L can be accommodated is not necessary to be stored in the lens ROM 67, but it can be provided with the photographic lens L by projecting a pin or the like thereon. The data stored in the ROM 67 is transmitted to the CPU on the camera body side through the above described electrical contact group TC by being controlled by the lens CPU 66 or in direct response to a request from the CPU on the camera body CB side. A camera system arranged as described above and having the above function is provided with a program for accommodating the photographic lens L shown in the flowcharts illustated in Figs. 4 through 7. First, the main flowcharts for accommodating the photographing lens shown in Figs. 4 and 5 will be described below, wherein a camera is in a photographing mode such as an AF mode or the like, and when the lock switch SW L as the main switch is turned off, this mode is set (note that a program step is referred to as S hereinafter). When the photographing mode is set as described above, first it is determined at S. 101 whether the lock switch SW L as the main switch is turned on or off. When the lock switch SW L is turned off, the flow goes to S. 102, and when it is turned on, the flow returns to the original mode. This is because the intention of a user to complete photographing cannot be confirmed. When the intention of the user to complete photographing is confirmed at S. 101, a timer interruption such as a shutter-release processing and the like is inhibited at S. 102. Then, an AF (Automatic Focusing) operation and a PZ (Power Zooming) operation are stopped at S. 103. and S. 104 (these stop subroutines will be described later). The AF operation and the PZ operation are stopped here because the photographic lens L may be driven in a direction opposite to an accommodating direction and thus it becomes necessary to protect the motors 60 and 61. Next, it is determined at S. 105 whether the AF mode switch (the third automatic focusing switch SW AF 3) is in the AF mode or in the manual mode position. When it is in the AF mode position, the flow goes to S. 106 where it is determined whether the focusing lens group of the photographic lens L mounted on the camera body CB can to be accommodated based on data read from the ROM 67. When the determination is YES, the AF motor 60 starts to drive the focusing lens group in a direction to reduce the total length of the photographing lens L at S. 107 and S. 108, and a flag mark is set to indicate that the focusing lens group is being driven for accommodation. Then it is determined at S. 109 whether the power zoom mode switch (the zoom changing switch SW PZ 1) is turned on or off. When the switch is turned on, it is determined at S. 110 whether the zooming lens group of the photographic lens L mounted on the camera body CB can be accommodated based on data read from the ROM 67. When the determination is YES, the flow goes to S. 113. On the other hand, when it is determined that the AF mode switch is turned to the manual mode at S. 105 and when it is determined that the focusing lens group of the photographic lens L mounted on the camera body CB is cannot be accommodated at S. 106, the same determinations as those made at S. 109 and S. 110 are made at S. 111 and S. 112, and when the power zoom mode switch is turned to a power zoom mode and the zooming lens group can be accommodated, the flow goes to the next S. 113. When, however, determinations other than above are made, the flow goes to S. 133 where a power hold is released to terminate the flow. At S. 113 and S. 114, the PZ motor 61 starts to drive the zooming lens group in a direction in which the total length of the photographic lens L is reduced, in response to the determinations made at S. 109, S. 110, S. 111 and S. 112. A flag mark is set to indicate that the zooming lens group is driven for accommodation, and the flow goes to S. 115. On the other hand, when it is determined at S. 109 and S. 110 that the power zoom mode switch is turned on and the zooming lens group cannot be accommodated, the flow skips S. 113 and S. 114 and goes to S. 115. At S, 115, a timer is started to determine a longer time (referred to as a maximum accommodation time) necessary to move the focusing lens over a distance between one end point and the other end point and the zooming lens over a distance between one end point and the other end point which distances are stored in the photographic lens as the inherent values of the lens ROM 67. Note that although the timer is started for the comparison based on time in this step, the lens accommodation also can be controlled by the maximum number of pluses by counting the number of pulses of the AF pulser 68 or the PZ pulser 69. At S. 116, it is determined whether the focusing lens group is being driven for accommodation. When the determination is YES, it is determined at S. 177 whether the AF mode switch (the third automatic focusing switch SW AF 3) is in the AF mode or in the manual mode position. When the switch is is the AF mode position, it is determined at S. 118 whether the pulses output from the AF pulser 68 have an interval of 100 msec or more. When the interval is 100 msec or more, the flow goes to S. 119. This is made to check if the focusing lens group is at an accommodation limit position because the pulses output from the AF pulser 68 having an interval of 100 msec or more mean that the focusing lens group arrives at an accommodation side end point, i.e., the accommodation limit position. On the other hand, when it is determined at S. 117 that the AF mode switch is turned to the manual mode position, the flow skips S. 118 and goes to S. 119 since no AF pulse is output. In addition, when AFP (the number of AF pulses) read from the AF pulser 68 is greater than a maximum number of pulses AFPmax necessary to accommodate the focusing lens group, which is stored in the lens ROM 67 as an inherent value of the photographic lens L at S. 120 and S. 121, the flow goes to S. 119 even if it is determined at S. 118 that the pulse outputs from the AF pulser 68 have an interval less than 100 msec since the drive system of the focusing lens group or the like is considered to fail. At S. 119, an AF operation stop subroutine is executed to stop the operation of the focusing lens. On the other hand, when the determination is YES at S. 121, the flow skips the AF operation stop subroutine at S. 119 and goes to S. 122 since operation is normally carried out. At S. 122, it is determined whether the zooming lens group is being driven for accommodation. When the determination is YES, it is determined at S. 123 whether the power zoom mode switch (the zoom changing switch SW PZ 1) is turned on or off. When the switch is turned on, it is determined at S. 124 whether the pulses output from the PZ pulser 69 have an interval of 100 msec or more. When the pulses output have an interval of 100 msec or more, the flow goes to S. 125 where a zooming operation stop subroutine is executed by the PZ motor to stop the operation of the photographic lens L. This is made for the same purpose as that at S. 118 because the pulses output from the PZ pulser 69 having an interval of 100 msec or more mean that the zooming lens group arrives at an accommodation side end point. On the other hand, when it is determined at S. 123 that the power zoom mode switch is turned off, the flow skips S. 124 and goes to S. 125 since no zoom pulse is output. In addition, when PZP from the PZ pulser 69 is greater than the maximum number of pulses PZPmax necessary to accommodate the zooming lens group, which is stored in the lens ROM 67 as the inherent value of the photographing lens L at S. 126 and S. 127, the flow goes to S. 125 even if it is determined at S. 124 that the pulse outputs from the PZ pulser 69 have an interval less than 100 msec since a drive system of the zooming lens group or the like is considered to fail. This is made for the protection of the motor and the like S. 121. At S. 125, a zooming operation stop subroutine is executed by the PZ motor to stop the operation of the photographic lens L, and the flow goes to S. 128. Furher, when it is determined at S. 122 that the zooming lens group is not being driven for accommodation, the flow skips S. 123 - S. 125 and goes to S. 128. When the determination is YES at S. 127, the operation is normally carried out, and then the flow skips S. 125 and goes to S. 128 since the zooming operation stop subroutine is not necessary to be executed by the PZ motor at S. 125. It is determined at S. 128 whether the focusing lens group is being driven for accommodation in response to the determinations at S. 122, S. 125 and S. 127. When the determination is YES, it is determined at S. 130 whether a time period measured by a timer which started its operation at S. 116 exceeds the maximum accommodation time stored in the lens ROM 67. When the determination is YES, the AF operation stop subroutine is executed at S. 131 to stop the operation of the focusing lens since it is considered that some troubles are caused in the photographic lens, or the focusing lens mounted on the camera body CB is exessively long. In addition, at S. 132, the zooming operation stop subroutine by the PZ motor is executed for the same purpose as the execution at S. 131 to stop the operation of the photographic lens L. Note that the control effected by the timer is to protect the motors and the like to insure dual safety together with S. 120, S. 121 and S. 126, S. 127. At S. 133, the power hold of the system is released to terminate the flow. On the other hand, when it is determined at S. 128 that the focusing lens group is not being driven for accommodation, it is determined at S. 129 whether the zooming lens group is being driven for accommodation. When the determination is YES, the flow goes to S. 130 and is terminated through the above S. 130-S. 133, and when the determination is NO, the flow goes to the above S. 133 as it is and is terminated by turning off the power hold. Further, when it is determined at S. 130 that the maximum accommodation time has not been elapsed, it is determined at S. 134 whether the main switch is turned off or not. When it is determined that the main switch is turned off, the flow returns to N and circulates through S. 116 - S. 130 and S. 134 to wait that the accommodation time has been elapsed or the AF motor or the PZ motor stops. When it is determined that the main switch is turned on, the accommodation of each lens group is stopped in this lens accommodation mode, and the flow returns to the AF photographing mode through an NG processing mode since it is considered that a user changes his mind to finish photographing during the lens accommodation process and operates the main switch (shown by K in Fig. 5). Next, the AF operation stop subroutine shown in Fig. 6 will be described. In the AF operation stop subroutine, first it is determined at S. 201 whether the focusing lens group is stopped. When the determination is YES, the flow skips the succeeding steps and returns because the AF operation is stopped. When the determination is NO, the drive of the focusing lens group is stopped at S. 202, and a flag mark is set to indicate that the focusing lens group is stopped S. 203, and then the flow returns. Next, the zoomig operation stop subroutine of Fig. 7 will be described. In the zooming operation stop subroutine, it is determined at S. 301 and S. 302 whether the zooming lens group is operated in a zooming range or in a macro range. When the zooming lens group is operated neither in the zooming range nor in the macro range, the flow returns as it is. When the zooming lens group is operated in at least one of the ranges, the drive of the zooming lens is stopped at S. 303 and a flag mark is set to indicate that the zooming lens group is stopped in the zooming range and the macro range at S. 304 and S. 305, and then the flow returns.

Claims: A camera body (CB) for use with a lens unit (L) interchangeably mountable to said camera body, wherein the lens unit includes movable photographic lens elements and means for transmitting data to said camera body, said data being representative whether the overall length of the lens unit can be changed so that accommodation of the lens unit is facilitated; the camera body comprising: camera control means (10) for disabling photographing; data receiving means (TC) for receiving data from the lens unit (L); means (10) to determine on the basis of the received data, whether the overall length of the lens unit can be changed; driving means (10, 19) responsive to said determining means and to said camera control means (10), for driving the lens elements in a direction to minimize the overall length of the lens unit (L), if the overall length of the lens unit (L) can be changed, and if photographing is disabled. The camera body according to claim 1 or 2, wherein said driving means comprises a pulse motor (19) and wherein said pulse motor (19) is operated until the number of pulses reaches a predetermined number. The camera body according to claim 1 or 2, wherein said driving means (19) is operated for a time necessary to move said photographic lens elements between one end point and the other end point of a moving range of said lens unit (L). The camera body according to any one of the foregoing claims, wherein said photographic lens elements are arranged in more than one lens group; wherein said driving means comprises more than one drive means (60, 61) corresponding to said lens groups, respectively; and wherein said more-than-one drive means (60, 61) are adapted to be driven until the longest time necessary to move respective lens groups in respective moving ranges thereof has passed. A camera system comprising: the camera body (CB) of any one of claims 1 to 4; and a lens unit (L) interchangeably mountable to the camera body (CB), comprising movable photographic lens elements; means (66) providing data representative whether the overall length of said lens unit (L) can be changed so that accommodation of the lens unit (L) is facilitated; means (TC) for transmitting said data to the camera body (CB). The camera system according to claim 5, wherein said photographic lens elements are arranged in more than one lens group which are independently movable; and wherein said data providing means (66) provides said data respectively of said lens groups. The camera system according to claim 5 or 6, wherein said lens unit (L) is an autofocus- and power zoom lens unit. The camera system according to claim 7, comprising: a main switch (SW L ) and a power zoom switch (SW PZ 1), means (S 102) for inhibiting a shutter release processing when the main switch (SW L ) is turned off, means (S 103, S 104) for stopping an automatic focusing operation and a power zooming operation, means (S 105) for determining whether an autofocus mode is effective, means (S 106) for determining whether a focusing lens group can change the overall length of said lens unit (L) by evaluation of said data received from the lens unit (L), means (S 107) for starting the driving means (60) for said focusing lens group to drive it in a direction to reduce the total length of said lens unit (L), means (S 109) for determining whether a power zoom mode is effective, means (S 110) for determining whether a zooming lens group can change the overall length of said lens unit (L) by evaluation of said data received from said lens unit (L), means (S 113) for starting the driving means (61) for said zooming lens group to drive it in a direction to reduce the total length of said lens unit (L).

Inventors: KAWASAKI MASAHIRO ASAHI KOGAKU, SUZUKI NOBORU ASAHI KOGAKU KOG, TOJI SHIGEO, KAWASAKI, MASAHIRO ASAHI KOGAKU KOGYO K.K., SUZUKI, NOBORU ASAHI KOGAKU KOGYO K.K., TOJI, SHIGEO
Applicants: ASAHI OPTICAL CO LTD, ASAHI KOGAKU KOGYO KABUSHIKI KAISHA
Application year: 1989
Main classification: G03B17
IPC codes: G02B7, G03B7, G03B17