Abstract: A zoom lens assembly includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves. The zoom lens include first and third lens groups which are both moveable by one of the two cam grooves in the direction of the optical axis. A second lens group movable, by a second of the two cam grooves in the direction of the optical axis is also provided, as well as a focusing mechanism, for moving the second lens group to a position which is determined by focal length data derived from actual positions of the first, second, and third lens groups and object distance data detected by an object distance measuring device. A method of controlling focusing of the zoom lens includes correcting an amount of deviation from focus caused by a zooming operation, by moving the focusing lens group.

Abstract: A zoom lens assembly includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves. The zoom lens include first and third lens groups which are both moveable by one of the two cam grooves in the direction of the optical axis. A second lens group movable, by a second of the two cam grooves in the direction of the optical axis is also provided, as well as a focusing mechanism, for moving the second lens group to a position which is determined by focal length data derived from actual positions of the first, second, and third lens groups and object distance data detected by an object distance measuring device. A method of controlling focusing of the zoom lens includes correcting an amount of deviation from focus caused by a zooming operation, by moving the focusing lens group.

Abstract: A zoom lens assembly includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves. The zoom lens include first and third lens groups which are both movable by one of the two cam grooves in the direction of the optical axis. A second lens group movable, by a second of the two cam grooves in the direction of the optical axis is also provided, as well as a focusing mechanism, for moving the second lens group to a position which is determined by focal length data derived from actual positions of the first, second, and third lens groups and object distance data detected by an object distance measuring device. A method of controlling focusing of the zoom lens includes correcting an amount of deviation from focus caused by a zooming operation, by moving the focusing lens group.

Abstract: A barrier mechanism for a zoom lens assembly which includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves. The barrier mechanism of the lens barrel includes a pair of barrier plate assemblies which are adapted to open and close an opening of the lens barrel, wherein each of the pair of barrier plate assemblies includes a pair of plate elements which are symmetrically arranged with respect to a center of the opening. In the closed position, the barrier plates are arranged side by side.

Abstract: A diaphragm mechanism in a zoom lens barrel includes a front movable lens group which is moved together with the diaphragm mechanism, a rear movable lens group located behind the front movable lens group, a diaphragm driving member which can engage with a diaphragm driving member provided on an associated camera body, and an intermediate drive transmitting member which transmits movement of the diaphragm driving member of the lens barrel to the diaphragm mechanism which is provided with a rear lens frame holding the rear movable lens group. The intermediate drive transmitting member is supported on the rear lens frame.

Abstract: A method and apparatus for molding an inflation film even from a thermoplastic resin having a small melt tension, in which a melt resin bubble extruded from an extruder is molded, while controlling a resin temperature of the bubble to a certain temperature range by an air ring provided with a plurality of annular slits for blowing cooling air in a take-up direction of the melt resin bubble and provided at a position at which the melt resin bubble is remarkably expanded, after (a) cooling air is blown to a melt resin bubble from a first air ring provided at the proximity of a die outlet to cool said melt resin bubble; and, then, the bubble is either (i) brought into contact, on the inner surface thereof, with the surface of a stabilizer provided on a die surface, or (ii) is supported in a non-contact state through an air layer, while being taken up.

Abstract: A cover unit for lens unit having a lens barrel, which has a cylindrical support member to be coupled to an end of the lens barrel, at least one engaging pin member is provided at a predetermined position on the outer circumferential surface thereof. Further, the cover unit has a cylindrical hood member capable of being superposed on the lens barrel, at least one cam groove to slidably receive the at-least-one engaging pin member therein being formed on the inner circumferential surface of the hood member, wherein by means of the engagement of the at-least-one engaging pin member with the at-least-one cam groove, the hood member moves in its axial direction relative to the support member upon rotation of the hood member relative to the support member. Lens barriers are supported by the support member for covering the end of the lens barrel, the lens barrier means being openable. The lens barriers are driven in accordance with the movement of the hood member.

Abstract: A method of controlling the focusing of a zoom lens which has a plurality of lens groups including at least one focusing lens group, wherein an amount of deviation from focus caused by a zooming operation is corrected by movement of the focusing lens group. The method includes setting a reference object distance, at which no deviation from focus occurs during zooming of the zoom lens, at a finite object distance, such that the amount of movement of the focusing lens group necessary to effect focusing is determined based upon a reference position corresponding to a position of the focusing lens group at the reference object distance, in accordance with focal length data and object distance data.

Abstract: Lenses, which include at least one plastic lens, are supported in a lens barrel by a lens holding structure which includes shoulder surfaces and inner circumferential surfaces of a lens barrel, at least one annular elastic member, and a retainer ring. The lenses are radially positioned in coaxial alignment with the lens barrel by the inner circumferential surfaces of the lens barrel, and axially positioned in engagement with the shoulder surfaces by the elastic member and the retainer ring. The elastic member elastically presses one of the lenses against one of the shoulder surfaces, and the retainer ring is threadedly mounted on the outer end of the lens barrel end holds the other lens against the other shoulder surface. Annular spacers may be disposed between the outer circumferential edges of the lenses and the inner circumferential surfaces of the lens barrel, for holding the lenses in coaxial alignment with the lens barrel.

Abstract: A method of controlling the focusing of a zoom lens which has a plurality of lens groups including at least one focusing lens group, wherein an amount of deviation from focus caused by a zoom operation is corrected by movement of the focusing lens group. The method includes setting a reference object distance, at which no deviation from focus occurs during zooming of the zoom lens, at a finite object distance, such that the amount of movement of the focusing lens group necessary to effect focusing is determined based upon a reference position corresponding to a position of the focusing lens group at the reference object distance, in accordance with focal length data and object distance data. The zoom lens assembly includes a stationary lens barrel and a rotatable cam ring which is supported on the stationary lens barrel for movement in the direction of the optical axis while being rotated, and which includes at least two cam grooves.

Abstract: A lens barrier for opening and closing a lens opening of a lens barrel, including a plurality of barrier plates which are spaced from one another in the direction of their thickness so as to slide in a direction perpendicular to the optical axis of the lens opening. A barrier driving mechanism is provided which moves the barrier blades between an open position in which the barrier blades are superimposed on one another outside the lens opening and a closed portion in which the barrier blades are located side by side in the lens opening to close the latter.