Abstract: An optical system includes, in order from object side: a positive first lens unit; and a positive second lens unit moving during focusing. The second lens unit includes, in order from object side, a front unit, an aperture stop, and a positive rear unit. The first unit includes a negative lens that has a convex surface facing object side and is arranged closest to object side, and three or more positive lenses on image side of the negative lens. A distance, on optical axis, from a lens surface on object side of a second positive lens counted from image side of the three or more positive lenses to a lens surface closest to image side of the first unit, and a distance, on optical axis, between a lens surface closest to object side and that closest to image side of the first unit are each appropriately set.

Abstract: An optical system includes, in order from object side: a positive first lens unit; and a positive second lens unit moving during focusing. The second lens unit includes, in order from object side, a front unit, an aperture stop, and a positive rear unit. The first unit includes a negative lens that has a convex surface facing object side and is arranged closest to object side, and three or more positive lenses on image side of the negative lens. A distance, on optical axis, from a lens surface on object side of a second positive lens counted from image side of the three or more positive lenses to a lens surface closest to image side of the first unit, and a distance, on optical axis, between a lens surface closest to object side and that closest to image side of the first unit are each appropriately set.

Abstract: A zoom lens which includes in order from an object side to an image side: a first lens unit with a positive refractive power; a second lens unit with a negative refractive power; and a subsequent lens unit. The second lens unit moves on an optical axis to increase an interval between the first and second lens units during zooming from a wide angle end to a telephoto end. The first lens unit includes a front side lens subunit immovable during focusing with a positive refractive power and a rear side lens subunit movable during focusing with a positive refractive power. A PR lens of the rear side lens subunit and a N2 lens of the second lens unit are made of a material wherein an Abbe number (?d) and a partial dispersion ratio (?gF) are suitably set.

Abstract: A zoom lens includes, from the object side, first and second lens units of negative and positive refractive power. The lens units move during zooming from the wide-angle end to the telephoto end. The first lens unit includes, from the object side, three negative lenses and a positive lens, at least one of the surfaces of these lenses being aspherical. A spherical surface whose center of curvature is on the optical axis and that includes a point of the intersection of a lens surface and the optical axis and a point on the lens surface determined by the effective aperture is referred to as reference spherical surface of the lens surface. In the first lens unit, the radiuses of curvature of the image-side reference spherical surface of the most object-side negative lens and the object-side reference spherical surface of the second most object-side negative lens are appropriately set.

Abstract: A zoom lens which includes in order from an object side to an image side: a first lens unit with a positive refractive power; a second lens unit with a negative refractive power; and a subsequent lens unit. The second lens unit moves on an optical axis to increase an interval between the first and second lens units during zooming from a wide angle end to a telephoto end. The first lens unit includes a front side lens subunit immovable during focusing with a positive refractive power and a rear side lens subunit movable during focusing with a positive refractive power. A PR lens of the rear side lens subunit and a N2 lens of the second lens unit are made of a material wherein an Abbe number (?d) and a partial dispersion ratio (?gF) are suitably set.

Abstract: A zoom lens includes, from the object side, first and second lens units of negative and positive refractive power. The lens units move during zooming from the wide-angle end to the telephoto end. The first lens unit includes, from the object side, three negative lenses and a positive lens, at least one of the surfaces of these lenses being aspherical. A spherical surface whose center of curvature is on the optical axis and that includes a point of the intersection of a lens surface and the optical axis and a point on the lens surface determined by the effective aperture is referred to as reference spherical surface of the lens surface. In the first lens unit, the radiuses of curvature of the image-side reference spherical surface of the most object-side negative lens and the object-side reference spherical surface of the second most object-side negative lens are appropriately set.

Abstract: A zoom lens system is disclosed which includes, in order from an object side to an image side, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit which have a positive, negative, positive and positive optical power, respectively, and at least the first, third and fourth lens units move during zooming so that the distance between the first and second lens units increases, the distance between the second and third lens units decreases and the distance between the third and fourth lens units decreases at the telephoto end compared to the wide-angle end. Then, by appropriately setting lens elements constituting each lens unit and focal lengths of the lens units which move during zooming, the present invention realizes high optical performance over the entire zooming range and entire image area while achieving a desired zoom ratio.

Abstract: This specification discloses a zoom lens having good optical performance over the whole of an object distance from an infinity object to a super-close range object. This zoom lens system comprises, in order from the front to the rear, a first lens unit of positive optical power, a second lens unit of negative optical power, and a following lens component of positive optical power as a whole. During zooming, the first lens unit moves so that the interval between the first lens unit and the second lens unit may become great at the telephoto end relative to the wide angle end. At least one lens unit moves for focusing resulting from a change in an object distance, and the lens unit moving for the focusing is provided with a diffractive optical surface.

Abstract: A zoom lens system is disclosed which includes, in order from an object side to an image side, a first lens unit, a second lens unit, a third lens unit and a fourth lens unit which have a positive, negative, positive and positive optical power, respectively, and at least the first, third and fourth lens units move during zooming so that the distance between the first and second lens units increases, the distance between the second and third lens units decreases and the distance between the third and fourth lens units decreases at the telephoto end compared to the wide-angle end. Then, by appropriately setting lens elements constituting each lens unit and focal lengths of the lens units which move during zooming, the present invention realizes high optical performance over the entire zooming range and entire image area while achieving a desired zoom ratio.

Abstract: A zoom lens includes a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a negative optical power in sequence from an object side. The zoom lens executes zooming by moving all the four lens units on an optical axis. At least one of the four lens units has at least one diffractive optical surface. By this arrangement, the size of the zoom lens can be easily reduced while securing a desired variable power ratio and correcting lateral chromatic aberration that is varied by zooming.

Abstract: This specification discloses a zoom lens having good optical performance over the whole of an object distance from an infinity object to a super-close range object. This zoom lens system comprises, in order from the front to the rear, a first lens unit of positive optical power, a second lens unit of negative optical power, and a following lens component of positive optical power as a whole. During zooming, the first lens unit moves so that the interval between the first lens unit and the second lens unit may become great at the telephoto end relative to the wide angle end. At least one lens unit moves for focusing resulting from a change in an object distance, and the lens unit moving for the focusing is provided with a diffractive optical surface.

Abstract: A zoom lens includes a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a negative optical power in sequence from an object side. The zoom lens executes zooming by moving all the four lens units on an optical axis. At least one of the four lens units has at least one diffractive optical surface. By this arrangement, the size of the zoom lens can be easily reduced while securing a desired variable power ratio and correcting lateral chromatic aberration that is varied by zooming.