Abstract: A zoom lens comprises four lens unit, and at the time of zooming, each of a distance between a first positive lens unit and a first negative lens unit and a distance between a second negative lens unit and a second positive lens unit changes, and a distance between the first positive lens unit and the second negative lens unit widens more at the telephoto end than at the wide angle end, and the first positive lens unit includes an object-side sub-lens unit and an image-side sub-lens unit, and an aperture stop is disposed between the object-side sub-lens unit and the image-side sub-lens unit, and the first negative lens unit includes a negative lens and a positive lens, and a refracting surface nearest to an image in the first negative lens unit is concave toward the image side, and a refracting surface nearest to an object in the second positive lens unit is concave toward the object side, and a refracting surface nearest to the image in the second positive lens unit is convex toward the image side, and the z

Abstract: The zoom lens has an aperture stop arranged between the second lens unit and the fourth lens unit. During zooming from the wide angle end to the telephoto end, the distances between the lens units vary in such a way that the distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end, the distance between the second lens unit and the third lens unit is smaller at the telephoto end than at the wide angle end, and the distance between the fourth lens unit and the fifth lens unit is larger at the telephoto end than at the wide angle end. The zoom lens satisfies the following conditional expression (1): 3.5?LTLw/IHt?8.9??(1).

Abstract: The zoom lens has an aperture stop arranged between the second lens unit and the fourth lens unit. During zooming from the wide angle end to the telephoto end, the distances between the lens units vary in such a way that the distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end, the distance between the second lens unit and the third lens unit is smaller at the telephoto end than at the wide angle end, and the distance between the fourth lens unit and the fifth lens unit is larger at the telephoto end than at the wide angle end. The zoom lens satisfies the following conditional expression (1): 3.5?LTLw/IHt?8.9??(1).

Abstract: An image forming lens system includes a front lens unit having a positive refractive power, and a rear lens unit, and does not include any other lens unit. The front lens unit includes a first lens unit having a positive refractive power and a second lens unit having a negative refractive power. Each of the first lens unit and the second lens unit includes a positive lens and a negative lens. The second lens unit is a focusing lens unit. The rear lens unit includes a positive lens and a negative lens. The second lens unit is the only lens unit that moves, in the front lens unit, and the following conditional expressions (1) and (2?) are satisfied: 0.5<fFF/f<1.65 ??(1) 0?|f/rG2b|<6.

Abstract: A single focal length lens system includes a front lens unit and a rear lens unit, and does not include any other lens unit. The front lens unit includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a negative refractive power. Each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the first lens unit and the second lens unit do not move all the time. An aperture stop is disposed on the image side of the second lens unit. Any one of the lens units positioned on the image side of the second lens unit is a focusing lens unit, and the following conditional expression (1) is satisfied: 0.06<|fG3/f|<0.

Abstract: An image forming lens system includes an aperture stop, and an image-side lens unit group which is disposed on an image side of the aperture stop. The image-side lens unit group includes a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power. Any one of the first image-side lens unit, the second image side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing, and the following conditional expression (1) is satisfied: 0.06<|ffo/f|<0.4 ??(1) where, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and ffo denotes a focal length of the focusing lens unit.

Abstract: A single focal length lens system includes a front lens unit having a positive refractive power, and a rear lens unit. The front lens unit includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and both the first lens unit and the second lens unit include a positive lens and a negative lens. The rear lens unit includes a focusing lens unit and a first predetermined lens unit. The first predetermined lens unit has a refractive power having a sign different from a refractive power of the focusing lens unit, and does not move at the time of focusing. The front lens unit does not include a lens which moves, and the rear lens unit does not include a lens which moves except at the time of focusing.

Abstract: A single focal length lens system includes in order from an object side to an image side along an optical axis, a front lens unit, and a rear lens unit which includes an aperture stop. The single focal length lens system does not include any other lens unit on the optical axis, and the rear lens unit includes a focusing lens unit having a negative refractive power. The focusing lens unit is disposed on the image side of the aperture stop, and moves along the optical axis at the time of focusing from an object at infinity to an object at a close distance. The front lens unit does not include a lens which moves in an optical axial direction, and the rear lens unit does not include a lens which moves in the optical axial direction except at the time of focusing.

Abstract: An image pickup apparatus includes a zoom lens and an image pickup element. The zoom lens includes a first positive lens unit, a first negative lens unit, a stop, and a second positive lens unit. For zooming, the first positive lens unit is stationary, the first negative lens unit moves, and the second positive lens unit moves. A position at a telephoto end of the first negative lens unit is on the image side of a position at the wide angle end. A position at a telephoto end of the second positive lens unit is on the object side of a position at the wide angle end. For focusing, the first positive lens unit is stationary. A first positive lens unit object-side system has a negative refractive power. A first positive lens unit image-side system has a positive refractive power. The image pickup apparatus satisfies predetermined conditional expressions.

Abstract: A zoom lens includes in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power. At the time of zooming, distances between the lens units change, and a distance between the first lens unit and the second lens unit at a telephoto end is shorter than a distance between the first lens unit and the second lens unit at a wide angle end, and an aperture stop is disposed on an image side of an image-side surface of the first lens unit, and on an object side of an image-side surface of the second lens unit, and the zoom lens satisfies the conditional expressions.

Abstract: A zoom lens includes a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power. At the time of zooming, distances between the lens units change, and a distance between the first lens unit and the second lens unit at a telephoto end is shorter than at a wide angle end. An aperture stop is disposed on the image side of an image-side surface of the first lens unit, and on the object side of an image-side surface of the second lens unit. The second lens unit includes two sub lens units. The object-side sub lens unit in the second lens unit includes one lens component. The following conditional expressions are satisfied. 3.0<?D12/ERS<4.5 1.05<|f3/fUN21|<2.

Abstract: The zoom lens has an aperture stop arranged between the second lens unit and the fourth lens unit. During zooming from the wide angle end to the telephoto end, the distances between the lens units vary in such a way that the distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end, the distance between the second lens unit and the third lens unit is smaller at the telephoto end than at the wide angle end, and the distance between the fourth lens unit and the fifth lens unit is larger at the telephoto end than at the wide angle end. The zoom lens satisfies the following conditional expression (1): 3.5?LTLw/IHt?8.9??(1).

Abstract: In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.

Abstract: An image pickup apparatus includes a zoom lens and an image pickup element. The zoom lens includes a first positive lens unit, a first negative lens unit, a stop, and a second positive lens unit. For zooming, the first positive lens unit is stationary, the first negative lens unit moves, and the second positive lens unit moves. A position at a telephoto end of the first negative lens unit is on the image side of a position at the wide angle end. A position at a telephoto end of the second positive lens unit is on the object side of a position at the wide angle end. For focusing, the first positive lens unit is stationary. A first positive lens unit object-side system has a negative refractive power. A first positive lens unit image-side system has a positive refractive power. The image pickup apparatus satisfies predetermined conditional expressions.

Abstract: A zoom lens includes a first lens group of positive refractive power; a second lens group of negative power; a third lens group of positive power; a fourth lens group of negative power, and a fifth lens group of positive power arranged from the object side to the image side. At activation of variable power from the wide angle end to the telescopic end, the first, third, fourth and fifth lens groups moves so as to get closer to the object side or the image side at the telescopic end than at the wide angle end; and a gap between the first lens group and the second lens group increases; a gap between the second lens group and the third lens group decreases; a gap between the third lens group and the forth lens group increases; and a gap between the forth lens group and the fifth lens group increases.

Abstract: A zoom lens comprising, in order from an object side thereof, a first lens group of positive refracting power, a second lens group of negative refracting power, an aperture stop, a third lens group of positive refracting power, a fourth lens group of negative refracting power, and a fifth lens group of positive refracting power. Upon zooming from the wide-angle end to the telephoto end, at least the first lens group and the aperture stop remain fixed in position, the second and third lens groups move in the optical axis direction, and the separation between each of the lens groups and the aperture stop changes. Upon focusing from a focusing-on-infinity state to a close-range-focusing state, the fourth lens group moves in the optical axis direction, with satisfaction of the following: ?0.36<f4/f1<?0.05??(1A), where fl and f4 are the focal lengths of the first and fourth lens groups, respectively.

Abstract: In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.

Abstract: An imaging optical system has, in order from the object side to the image side thereof, a front lens group, an aperture stop, and a rear lens group. A lens located closest to object side in said front lens group always remains fixed in position, with satisfaction of the following conditions (1) and (2): 1.15?fb/IH??1.7 ??(1) ?4.0?fn/f??1.3 ??(2) where f is a focal length of the whole imaging optical system, fn is a focal length of a first negative lens in said front lens group, fb is a back focus of the imaging optical system upon focusing on an object point at infinity, and IH? is a distance from an optical axis of a position where a chief ray from a maximum incident half angle of view (?) upon focusing on an object point at infinity is imaged at the imaging plane.

Abstract: A zoom lens includes a first lens group of positive refractive power; a second lens group of negative power; a third lens group of positive power; a fourth lens group of negative power, and a fifth lens group of positive power arranged from the object side to the image side. At activation of variable power from the wide angle end to the telescopic end, the first, third, fourth and fifth lens groups moves so as to get closer to the object side or the image side at the telescopic end than at the wide angle end; and a gap between the first lens group and the second lens group increases; a gap between the second lens group and the third lens group decreases; a gap between the third lens group and the forth lens group increases; and a gap between the forth lens group and the fifth lens group increases.

Abstract: A zoom lens comprising, in order from an object side thereof, a first lens group of positive refracting power, a second lens group of negative refracting power, an aperture stop, a third lens group of positive refracting power, a fourth lens group of negative refracting power, and a fifth lens group of positive refracting power. Upon zooming from the wide-angle end to the telephoto end, at least the first lens group and the aperture stop remain fixed in position, the second and third lens groups move in the optical axis direction, and the separation between each of the lens groups and the aperture stop changes. Upon focusing from a focusing-on-infinity state to a close-range-focusing state, the fourth lens group moves in the optical axis direction, with satisfaction of the following: ?0.36<f4/f1<?0.05??(1A), where f1 and f4 are the focal lengths of the first and fourth lens groups, respectively.