Abstract: A refractive-type zoom lens optical system includes a first lens group having a negative lens power and including a reflection member, a second lens group having a negative lens power, a third lens group having a positive lens power, a fourth lens group having a negative lens power, and a stop between the second lens group and the third lens group, wherein an overall length of the system is fixed during zooming and focusing.

Abstract: Disclosed is a compact zoom lens system having a image stabilizing function. This zoom lens system is provided with a plurality of lens units of which the interval between adjacent ones is changed during zooming. Shake correction is effected by a part of a lens unit of negative optical power of the plurality of lens units. Specifically, the lens unit of negative optical power is comprised of two lens components of negative optical power, and one of these two lens components is moved so as to have a component in a direction perpendicular to an optical axis to thereby change the imaging position of the zoom lens system.

Abstract: An image pickup apparatus having an optical path reflecting zoom lens system includes a zoom lens system, and an image pickup element which is disposed at an image side of the zoom lens system. The zoom lens system includes in order from an object side thereof a first lens unit G1 having a positive refracting power, which includes a reflecting optical member having a reflecting surface which reflects an optical path, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, a fourth lens unit G4 having a positive refracting power, and an aperture stop S which is disposed between the second lens unit G2 and the fourth lens unit G4. The first lens unit G1 has a position fixed with respect to a position of the image pickup element. At least the second lens unit G2 and the fourth lens unit G4 move and the zooming is carried out from a wide angle end to a telephoto end by changing a distance between each of lens units.

Abstract: A zoom lens system comprises, in order from an object side, a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; a fourth lens unit having a negative refractive power; and a fifth lens unit having a positive refractive power, and during magnification change from a wide-angle end to a telephoto end, each of the space between the respective lens units changes.

Abstract: A zoom optical system has lens groups, and performs zooming by varying distances between the respective lens groups in an optical axis direction thereof. The zoom optical system has two or more lens groups having a negative optical power and a positive optical power in this order from an object side. The first lens group (Gr1) and the second lens group (Gr2) each have three or less lens elements. The second lens group (Gr2) includes a positive lens element having a refractive index of 1.7 or more. The positive lens element has at least one aspherical surface. With this arrangement, provided are a compact and superfine zoom optical system with a zoom ratio of about two to three times, an imaging lens device incorporated with the zoom optical system, and a digital apparatus loaded with the imaging lens device.

Abstract: An optical apparatus is disclosed, which is capable of suppressing an image blur at the start of zooming. The optical apparatus comprises a memory storing data indicating the position of a second lens unit according to the position of a first lens unit, and a controller. The controller controls the drive width of the second lens unit at a third position with a first driving condition in a case where the drive of the first lens unit is started from a first position, and controls the drive width of the second lens unit at the third position with a second driving condition in a case where the drive of the first lens unit is started from a second position. The drive width of the second lens unit at the third position with the first driving condition is smaller than that with the second driving condition.

Abstract: The present invention provides a camera system which comprises: a zoom lens; phototaking means converting an image captured by the zoom lens into an electric image signal; and image control means, in which the zoom lens is made up of a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, a fourth lens group having negative refracting power, and a fifth lens group having positive refracting power, which are disposed in this order from an object side, and is configured so that the first lens group, the third lens group, and the fifth lens group are stationary; the second lens group is shifted in an optical axis direction to mainly perform variable power; and the fourth lens group is shifted in the optical axis direction to perform correction for image position fluctuations and focusing.

Abstract: A magnification varying optical system that directs light from an object to an image sensor includes in order from the object side: a first lens unit having negative optical power and including an optical axis changing element that changes the optical axis; a second lens unit having positive optical power and including three lens elements; a third lens unit having negative optical power; and a fourth lens unit having positive optical power. In this magnification varying optical system, in magnification varying from the wide-angle end to the telephoto end, the first lens unit is stationary, the distance from the first lens unit to the second lens unit decreases, and the distance from the third lens unit to the fourth lens unit increases. The magnification varying optical system satisfies the specified conditions.

Abstract: A zoom lens is provided and has a first group having a positive refractive power, a second group having a negative refractive power, an aperture stop, a third group having a positive refractive power and a fourth group having a positive refractive power, which groups are arranged in this order from the object side. The first group has a three-group four-lens configuration where a cemented lens of a negative lens and a positive lens, and two positive single-lenses and are disposed in this order from the object side. The second group has a three-group four-lens configuration where two single-lenses and each having a negative refractive power with a strong concave surface on the image side, and a cemented lens of a double-concave lens and a positive lens are disposed in this order from the object side.

Abstract: A four-unit zoom lens system includes in order from an object side, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a positive refracting power, in which at a time of zooming from a wide angle end to a telephoto end, at least the first lens unit, the second lens unit, and the third lens unit move, and a space between the lens units changes, and a total number of lenses in the second lens unit is not more than three, and the zoom lens system satisfies the following conditional expressions. 1.2<(?2t/?2w)/(?3t/?3w)<6.0 and ??(1A) 3.0<ft/fw<20.

Abstract: The invention relates to a high-performance, high-zoom-ratio zoom lens that can be much more reduced in terms of thickness upon received at a collapsible lens mount, and an imaging system incorporating the same. The zoom lens comprises a positive first lens group G1, a negative second lens group G2, a positive third lens group G3 and a positive fourth lens group G4. Upon zooming from the wide-angle end to the telephoto end, the first G1, the second G2, the third G3 and the fourth lens group G4 each move such that the air spacing between the first G1 and the second lens group G2 grows wide, the air spacing between the second G2 and the third lens group G3 becomes narrow, and the air spacing between the third G3 and the fourth lens group G4 grows wide.

Abstract: A zoom lens includes first to fifth lens units arranged in sequence from an object side to an image side, and having positive, negative, positive, negative, and positive refractive powers in that order. The zoom lens performs zooming by moving the first to fifth lens units. The fourth lens unit includes a negative lens, which is moved in such a manner as to have a component in a direction orthogonal to an optical axis so as to shift an image formed with an entire system in the direction orthogonal to the optical axis. The zoom lens satisfies the condition, 0.50<|ft/f4|<1.50, where ft is a focal length of the entire system, and f4 is a focal length of the fourth lens unit, both at the telephoto end.

Abstract: There is provided a zoom lens system including at least a first lens group GR1 having a positive refractive power, a second lens group GR2 having a negative refractive power, a third lens group GR3 having a positive refractive power, a fourth lens group GR4 having a negative refractive power, a fifth lens group GR5 having a positive refractive power, and a sixth lens group GR6 having a negative refractive power, arranged sequentially from the object side. Zoom ratio is varied by changing the distance between the adjacent lens groups.

Abstract: In a thin projector for projecting an image from a light valve such as a DMD, a compact zoom lens comprises, in order, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens-group having a negative refractive power, and a fourth lens group having a positive refractive power. The fourth lens group is fixed while the focal length is being changed. The first and second lens group are movable on an optical axis in a direction from the enlarging side towards the reducing side over a range from a wide angle end to an intermediate range, and are movable on the optical axis in a direction from the reducing side towards the enlarging side over a range from the intermediate range to a telephoto end. The third lens group moves on the optical axis in a direction from the reducing side to the enlarging side over a range from the wide angle end to the telephoto end, whereby the focal length of the whole lens system of the zoom lens is changed.

Abstract: Disclosed is a zoom lens optical system including: a first lens group that is provided close to an object, has a negative refractive power in total, and includes an optical part having a surface that reflects light; a second lens group that has a negative refractive power in total; an iris; a third lens group that has a positive refractive power in total; and a fourth lens group that has a positive refractive power in total. At least one of the second lens group, the third lens group, and the fourth lens group is moved to vary magnification. The second lens group is moved to perform focus adjustment when a distance to an object is changed between a long distance to a short distance, and the distance from a first lens of the first lens group to an imaging surface is fixed even when the lens moves during a change in magnification and the focus adjustment.

Abstract: A collapsible type optical unit is described that is capable of moving its optical system between a working position and a retracted position as well as an image-pickup apparatus including the optical unit. The optical unit and the image-pickup apparatus are capable of acquiring lens-position information by detecting a position of a lens barrel supported to be movable with respect to a fixed barrel. The collapsible type optical unit includes a second group lens frame movable along a direction of its optical axis with respect to a fixed ring and rear barrel, and a solid-state image-pickup device provided behind the second group lens frame, in which on the movable second group lens frame, a position-detecting means for detecting a position of the second group lens frame is provided.

Abstract: A zoom lens system comprises, in order from an object side, a positive first lens unit including a reflective optical element, a negative second lens unit, a positive third lens unit and a positive fourth lens unit, or a positive first lens unit, a negative second lens unit, a positive third lens unit, a negative fourth lens unit and a positive fifth lens unit. During zooming from a wide-angle end toward a telephoto end, the first lens unit is fixed, at least the second and third lens units move, and a space between the lens units changes. The second lens unit is positioned closer to an image-surface side in the telephoto end than in the wide-angle end, and the third lens unit is positioned closer to the object side in the telephoto end than in the wide-angle end. An image taking apparatus including the zoom lens system is also disclosed.

Abstract: There is disclosed a zoom lens system including, in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, and further including an aperture stop S disposed between the second lens unit and the third lens unit, during zooming from a wide-angle end to a telephoto end, a space between the lens units is changed, the first lens unit includes a single lens having a negative refractive power, a reflective optical element having a reflective surface which reflects an optical path and a sub unit having a positive refractive power, and the zoom lens system satisfies predetermined conditions.

Abstract: Disclosed is a zoom lens, which includes, in sequence from an object side to an image side, a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, a fifth lens group, a negative sixth lens group and a positive lens group. The first, third, fifth and seventh lens groups are fixed. When the zoom lens is made to zoom from a wide-angle end to a telephoto end, the second and fourth lens groups move toward the third lens group, while the sixth lens group moves toward the seventh lens group. The absolute value of the ratio of the focal distance of the second lens group to that of the sixth lens group is within a range between 0.1 and 0.5.

Abstract: The invention relates to a telephoto lens that can easily have high resolving power best suited for use with digital cameras and maintain the integrity of performance even at the nearest distance and a telephoto lens system that incorporates the same and is best suited for use with lens interchangeable digital cameras. The telephoto lens comprises, in order from its object side, a first lens group G1 having positive refracting power, a second lens group G2, a third lens group G3 having positive refracting power and a fourth lens group G4 having negative refracting power. An aperture stop S is interposed between the second lens group G2 and the fourth lens group G4, and the second lens group G2 comprises a positive lens and a negative lens.

Abstract: A zoom optical system has, in order from the object side, a first lens unit with negative refracting power, including a single lens component; a second lens unit with positive refracting power, simply moved toward the object side when the magnification of the zoom optical system is changed in the range from a wide-angle position to a telephoto position; a third lens unit with negative refracting power; and a fourth lens unit with positive refracting power. In focusing on an object point separated at least 300 times a focal length at the wide-angle position, when the magnification is changed in the range from the wide-angle position to the telephoto position, the third lens unit and the fourth lens unit are moved together so that a relative spacing between the third lens unit and the fourth lens unit is widened or the fourth lens unit approaches an imaging point.

Abstract: An imaging system includes a wavelength dependent aperture stop, which transmits light with different ranges of wavelengths through apertures of different diameters. Thus, different colored light will have different F-stops, which can be selected based on the power transfer and image quality requirements for the different colored light. For example, a smaller F-stop may be used with a weaker light source to produce a higher throughput for a specific range of wavelengths. Accordingly, the optical system's design and optimization is wavelength and F-stop dependent.

Abstract: A zoom lens of the invention has three lens groups. In the zoom lens, magnification change is performed by moving only one lens group among the three lens groups, and focus adjustments is performed by moving one of a first lens group and a second lens group counted from an enlargement conjugate side among the three lens groups. In addition, the zoom lens is approximately telecentric on reduction conjugate side thereof.

Abstract: A zoom lens includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power. When a lens positional state changes from a maximum wide angle state to a maximum telephoto state, the second lens group moves on an optical axis toward an object, and the first and the third lens groups also move in an optical axis direction such that a gap between the first lens group and the second lens group decreases, while gap between the second lens group and the third lens group is increased. When a change in subject position occurs, close-range focusing is performed by movement of the third lens group, and image shift is provided by shifting the second lens group in directions approximately perpendicular to the optical axis.

Abstract: A projection lens that, though designed for right projection, shows good aberration performance and can realize specifications required for a projection display apparatus, such as a low F number, a wide angle, a long back focus, and a high relative illumination, with a rational configuration is provided. A projection lens 1 of the present invention for magnifying and projecting an optical image formed on a spatial light modulator (disposed near an image plane 5) onto a screen 4 is constituted by a front lens group 2 and a rear lens group 3 that are arranged in this order from the screen 4 side toward the image plane 5 side. The rear lens group 3 is provided with a aperture stop 6 that is eccentric with respect to an optical axis 7 common to the front lens group 2 and the rear lens group 3. Focus adjustment is performed by moving the rear lens group 3 in a direction of the optical axis 7 without rotating it.

Abstract: A variable focal length lens system includes first to fourth lens groups having positive, negative, positive, and positive powers, respectively, and a fifth lens group arranged in this order from an object side. When a lens zoom position is changed from a wide-angle to a telephoto, the first to fourth groups are movable and the second group is moved towards the image side and the third group is moved towards the object side so that a distance between the first and second groups increases and a distance between the second and third groups decreases, and the fourth group is moved along an optical axis direction so as to compensate for the positional change in the image plane. The fifth group includes a negative subgroup having negative power and a positive subgroup disposed on the image side of the negative subgroup and having positive power, and a predetermined condition is satisfied.

Abstract: A zoom lens includes a first lens band having a positive focal length, a second lens band having a negative focal length, and at least third to fifth lens bands having positive focal lengths. An aperture diaphragm is located in the vicinity of the third lens band. When magnification i.e., zooming is performed from short to long focal point ends, the second lens band smoothly moves toward the third lend band and the fourth lens band simultaneously moves from the fifth lens band side toward a long focal point end so as to shear a magnification function together with the second lens band.

Abstract: A zoom optical system comprises in order from an object side, the first lens group consisting of one cemented lens in which each of the surfaces contacted with air is aspherical, and having negative refracting power as a whole, the second lens group consisting of one positive single lens and one cemented lens, and having positive refracting power as a whole, the third lens group of one negative lens having an aspherical surface, and the fourth lens group consisting of one positive lens having an aspherical surface. When magnification is carried out, each of the lens groups is moved while changing each relative distance among the lens groups.

Abstract: A zoom optical system has, in order from the object side, a first lens unit with negative refracting power, including a single lens component; a second lens unit with positive refracting power, simply moved toward the object side when the magnification of the zoom optical system is changed in the range from a wide-angle position to a telephoto position; a third lens unit with negative refracting power; and a fourth lens unit with positive refracting power. In focusing on an object point separated at least 300 times a focal length at the wide-angle position, when the magnification is changed in the range from the wide-angle position to the telephoto position, the third lens unit and the fourth lens unit are moved together so that a relative spacing between the third lens unit and the fourth lens unit is widened or the fourth lens unit approaches an imaging point.

Abstract: A compact rear projection image display apparatus in which the projection distance in a projection optical system is substantially reduced and no reflection mirror is used, thereby eliminating a major cause of image trapezoidal distortion. The rear projection image display apparatus has a projection lens system which includes a first lens group with positive refractive power and a second lens group which further enlarges an image enlarged by the first lens group. The projection lens system enlarges and projects an image displayed on an image display device, on a transmission screen. No reflection mirror is provided between the second lens group and the transmission screen and the image enlarged by the second lens group is directly projected on the transmission screen.

Abstract: A zoom lens system comprising, a first negative lens unit; a second positive lens unit; and a third negative lens unit, wherein a space between the second and third lens units changes during magnification change or focusing operation; the second lens unit and the third lens unit move only to the object side during the magnification change from a wide-angle end to a telephoto end so that a space between the first and second lens units is narrower in the telephoto end than in the wide-angle end; the first lens unit comprises a negative lens and a positive lens; the second lens unit comprises at most three lenses; the third lens unit comprises a negative lens; and the following condition (1) is satisfied: 0.7<Cj(t)/Cj(w)<1.2.

Abstract: Providing a zoom lens system that satisfies making the focusing lens light and reducing a moving amount for focusing, simultaneously. The zoom lens system includes a first lens group having positive power, a second lens group having negative power and a third lens group having positive power. When zooming from a wide-angle end state to a telephoto end state, at least the first and third lens groups are moved such that a distance between the first and second lens groups increases, and a distance between the second and third lens groups decreases. The first lens group is composed of a front lens group with positive power having at least one negative lens and at least one positive lens, and a rear lens group with positive power having one positive lens. Focusing from infinity to a close object is carried out by moving only the rear lens group to the object.

Abstract: A focusing group G1 is disposed on an object side relative to a variator group G2. The focusing group G1 includes, in order from the object side, a first group G11 having a positive refractive power, a second group G12 having a positive refractive power, and a third group G13 having a positive refractive power. The first group G11 has, in order from the object side, at least one concave lens (L11) and at least one convex lens. When focusing from an infinitely distant object to a close object, the second group G12 and the third group G13 are moved so that with respect to a change in an object distance, an amount of movement of the second group G12 becomes large in a region near infinity, while an amount of movement of the third group G13 becomes large in a close range.

Abstract: Object is to provide an inner-focusing type zoom lens system carrying out focusing by moving a portion of a first lens group suitable for an auto-focus SLR camera. A zoom lens system includes, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, a distance between the first and the second lens groups increases, and a distance between the second and the third lens groups decreases. The first lens group is composed of, in order from the object, a 1A lens group G1A having positive refractive power, and a 1B lens group G1B having positive refractive power. Focusing from infinity to a close-range object is carried out by moving only the 1B lens group G1B to the object.

Abstract: Providing a zoom lens system with a vibration reduction function, a high zoom ratio, and a wide angle of view, an imaging apparatus, a method for vibration reduction, and a method for varying a focal length. The system includes, in order from an object, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having positive power. Upon zooming from a wide-angle end to a telephoto end, a distance between the first and the second lens groups increases, a distance between the second and the third lens groups decreases, and a distance between the third and the fourth lens groups varies. The third lens group consists of a front group and a rear group. Vibration reduction is carried out by moving only the rear group perpendicularly to the optical axis. Given conditions are satisfied.

Abstract: In this invention, to provide a compact zoom lens having a small number of optical element groups to be driven and a simple moving mechanism, at least one of a plurality of optical element groups arranged in the lens system includes a refractive power variable element of a transmission type which has a compensation function to correct focus movement caused by zooming and a focus function to correct focus movement caused by a variation in inter-object distance. The refractive power variable element is a liquid optical element including a first liquid having a conductivity or a polarity and a second liquid which is not mixed with the first liquid, the first liquid and the second liquid being enclosed in a container fluid-tight so as to define an interface therebetween having a predetermined shape, the liquid optical element being arranged such that a refractive power thereof is adjusted by changing a curvature of the interface.

Abstract: A zoom lens that is designed to enable a thinner image pickup device includes, in order from the object side, a first lens group having positive refractive power and a reflecting surface for folding the optical axis of the zoom lens approximately ninety degrees, a second lens group having negative refractive power, a third lens group having positive refractive power with a stop at its image side, and a fourth lens group having positive refractive power. The second lens group and the fourth lens group move along the optical axis during zooming, and the fourth lens group moves along the optical axis during focusing. The four lens groups have particular constructions and the zoom lens satisfies specified conditions related to the focal lengths of specified lens groups, the focal length of the zoom lens at the telephoto end, and the Abbe number of a specified lens element.

Abstract: A zoom lens of the invention has three lens groups. In the zoom lens, magnification change is performed by moving only one lens group among the three lens groups, and focus adjustments is performed by moving one of a first lens group and a second lens group counted from an enlargement conjugate side among the three lens groups. In addition, the zoom lens is approximately telecentric on reduction conjugate side thereof.

Abstract: The present invention provides a zoom lens provided with, in order from an object side: a first lens group having a positive refractive power whose position on the optical axis is fixed during a zooming operation and a focusing operation; a second lens group having a negative refractive power; a third lens group having a positive refractive power; a fourth lens group having a positive refractive power; a fifth lens group having a negative refractive power; and a sixth lens group having a positive refractive power. The first lens group includes a reflection optical element. At least the fifth lens group is used for focusing on an object at a finite distance. The maximum lateral magnification of the predetermined lens groups between a wide-angle end and a telephoto end of the zoom lens and focal lengths of the zoom lens satisfy a predetermined condition.

Abstract: A zoom lens system comprising a plurality of lens units each composed of at least one lens element, wherein an interval between at least any two lens units is changed so that an optical image is formed with a continuously variable magnification, the zoom lens system comprises a first lens unit having positive power, a second lens unit that includes a lens element having a reflecting surface and has negative power and subsequent lens units including at least one lens unit having positive power, and the condition: 0.50<(C?S)/H<1.00(C=?{square root over ( )}(2R·dR?dR2), S is a sag of the image side surface of the most object side lens element in the second lens unit at height H, H is one-half of an optical axial thickness of the lens element having a reflecting surface, R is a radius of curvature of the image side surface, and dR is an interval between the most object side lens element and the lens element having a reflecting surface) is satisfied.

Abstract: A wide-angle imaging lens comprises, in order from an object: a first lens having a negative refractive power; a second lens having a positive refractive power with a convex face directed to the object; an aperture diaphragm; a third lens having a positive refractive power with a convex face directed to an image; and a fourth lens having a positive refractive power with a convex face directed to the object, wherein the following conditional expressions are satisfied. N2?1.7 ??(1) N3?1.7 ??(2) N4?1.7 ??(3) when N2: a refractive index of the second lens at the d-line N3: a refractive index of the third lens at the d-line N4: a refractive index of the fourth lens at the d-line.

Abstract: A zoom lens includes, in order from an object side, a first group having a positive refractive power, a second group having a negative refractive power, a diaphragm, a third group having a positive refractive and a fourth group following the third group. When a power of the zoom lens varies from a wide-angle end to a telephoto end, the second group is moved along an optical axis toward an image side with the first and third groups fixed to the optical axis so as to vary the power and the fourth group is moved along the optical axis to perform correction of a position of the image plane, which is associated with the variation of the power, and focusing.

Abstract: A zoom lens unit includes: a positive first lens group; a negative second lens group; and a positive subsequent lens group as a whole, the subsequent lens group includes a third lens group, and an aperture stop is disposed between the second lens group and the third lens group, and a lens construction including the first and the second lens groups satisfies the condition (1): 1.0<ri/ri+1<5.0, in which ri and ri+1 are curvature radii of lens surfaces Si and Si+1 in the lens construction, respectively, the lens surfaces Si and Si+1 being “i”th and “i+1”th lens surfaces, respectively, counted from the object side, and a reflectivity-reducing treatment adapted to reduce intensity of a ghost image is performed on each lens surface forming at least one of pairs of lens surfaces satisfying the condition (1).

Abstract: A zoom lens system includes negative first lens group, a positive second lens group and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, all of the negative first lens group, the positive second lens group and the positive third lens groups are arranged to move in the optical axis direction. The negative first lens group includes a negative lens element, a negative lens element and a positive lens element, in this order from the object. The positive second lens group includes a positive lens element, a positive lens element, a negative lens element, and a positive lens element, in this order from the object. The zoom lens system satisfies the following condition: 1.2<|f1G|/f2G<1.5 ??(1) wherein f1G designates the focal length of the negative first lens group (f1G<0); and f2G designates the focal length of the positive second lens group.

Abstract: A zoom lens of rear focus type in which a total lens system is able to be miniaturized by further miniaturizing a prism, without deteriorating an optical performance. The zoom lens has a first lens group (GR1) to a fifth lens group (GR5) having refraction powers of a positive, negative, positive, positive and negative from the object side in this order, respectively, and is configured to carry out a zooming operation by moving the second lens group (GR2) and the fourth lens group (GR4). In addition, the first lens group has a front-side lens group having an negative refracting power, an optical element for folding an optical path, and a backside lens group having a positive refracting power, from the object side in this order, and further a condition of 1.3<?5<2.2 is satisfied, provided that an imaging magnification of the fifth lens group (GR5) at where an object distance is at infinity is ?5.

Abstract: A telescopic zoom lens system includes first through fourth lens groups, wherein upon zooming from the short to long focal length extremities, the first and fourth lens groups remain stationary, the second lens group moves toward the image side, and the third lens group moves toward the image side and thereafter moves toward the object side. The first lens group includes positive first and second sub-lens groups, the second sub-lens group being a focusing lens group and including a negative meniscus lens element having a convex surface on the object side and a positive lens element having a convex surface on the object side. The following condition (1) is satisfied: 2.7<flR/ft<3.5; ??(1) wherein flR and ft designate the focal lengths of the second sub-lens group and the entire zoom lens system at the long focal length extremity, respectively.

Abstract: A zoom lens sequentially includes, along an optical axis from the object (to be imaged) side, a first lens group which has positive refracting power and is always fixed at a position in the optical axis direction in zooming and focusing, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth lens group having positive refracting power. Zooming is performed by moving at least the second lens group and fourth lens group. Focusing is performed by moving at least the fourth lens group. The first lens group includes an optical element having an effect of bending the optical path of a light beam and satisfies the following conditional expression: 2.0<f1/fw<4.5 where f1 is the focal length of the first lens group and fw is the focal length of the zoom lens at the wide-angle end.

Abstract: A zoom lens system includes a first group G1 of positive power, a second group G2 of negative power, a third group G3 of positive power and a fourth group G4 of positive power. Upon zooming, at least the first group G1, the second group G2 and the third group G3 move on an optical axis in such a way that, at a telephoto end with respect to a wide-angle end, the space between the first group G1 and the second group G2 and the third group G3 becomes narrow and the space between the third group G3 and the fourth group G4 becomes wide. The zoom lens system satisfies a condition that defines the ratio of the total length (length from the first surface of the lens system to an image plane) to the focal length of the zoom lens system at the wide-angle end.

Abstract: Providing a zoom lens system that can excellently correct aberrations over entire range from a wide-angle end state W to a telephoto end state T in spite of having a high zoom ratio including, in order from an object, a first group G1 having positive power, a second group G2 having negative power, a third group G3 having positive power, a fourth group G4 having negative power, and a fifth group G5 having positive power. When zooming from the wide-angle end state W to the telephoto end state T, a distance between the first group G1 and the second group G2 increases, a distance between the second group G2 and the third group G3 decreases, a distance between the third group G3 and the fourth group G4 increases, and a distance between the fourth group G4 and the fifth group G5 decreases. Given conditions are satisfied.

Abstract: The invention provides a zoom lens system much more reduced in size and cost than ever before and best-suited for use on portable information terminals of small size. The zoom lens system comprises, in order from an object side thereof, a first lens group G1 having positive refracting power and designed to be fixed during zooming, a second lens group G2 having negative refracting power and designed to move from the object side to an image plane side of the system for zooming from a wide-angle end to a telephoto end of the system, a third lens group having refracting power and designed to move from the image plane side to the object side for zooming from the wide-angle end to the telephoto end, and a fourth lens group G4 having positive refracting power and designed to be movable during zooming.