Abstract: A zoom lens has a field view of 60° to 70° at a wide-angle end, a magnification change ratio of about five to six times, and a small number of component lenses, enables retraction to a compact size when not in use, provides high resolution, and is compatible with a compensation function for zoom lens vibrations. Comprised are, in order from an object side, a first lens unit (G1) of positive optical power, a second lens unit (G2) of negative optical power, a third lens unit (G3) of positive optical power, and a fourth lens unit (G4) of positive optical power. When zooming from the wide-angle end to a telephoto end, the first lens unit (G1) and the second lens unit (G2) move so as to trace a convex path toward an image side, and the third lens unit and the fourth lens unit (G4) move monotonously toward an object side.

Abstract: In a lens barrel for holding an imaging optical system that forms an optical image of an object, the imaging optical system comprises an object side lens unit 4 onto which light ray from the object is incident and a reflective optical element 5 having a reflecting surface 5a for bending the light ray exiting from the object side lens unit 4, and in an imaging state, the object side lens unit 4 is held in a manner movable in a direction of the light ray from the object, and while in an accommodated state, the reflective optical element 5 is escaped to an escape position different from a position located in the imaging state.

Abstract: It is an object to provide a zoom lens made of three groups having a zoom ratio of ×2.5 to ×3.2 if the object distance is ?, an field angle at the wide-angle end of 60° to 70°, high resolution, and a short optical total length when not in use. The zoom lens is made of a first lens group (G1) with a negative power, a second lens group (G2) with a positive power, and a third lens group (G3) with a positive power, arranged in that order from an object side to an image plane (S) side. The first lens group (G1) is made of a first lens (L1) that is a negative meniscus lens whose surface with strong curvature is facing the image plane (S) side and a second lens (L2) that is a positive meniscus lens whose surface with strong curvature is facing the object side, arranged in that order from the object side.

Abstract: A zoom lens system, in order from the object side to the image side, comprises a first lens unit G1 having positive optical power, a second lens unit G2 having negative optical power, a third lens unit G3 having positive optical power and a fourth lens unit G4 having positive optical power. Magnification varying is performed by varying the distances between the lens units by moving the lens units along the optical axis. The third lens unit G3 comprises at least two lens elements including a third lens unit object side lens element which is a positive lens element disposed on the most object side and whose high-curvature surface faces the object side and a third lens unit image side lens element which is a negative lens element disposed on the most image side and concave to the image side.

Abstract: An object is to provide a high-resolution zoom lens system which has fewer lens elements and therefore, can be retracted into a compact form when not in use; and the zoom lens system, in order from the object side, comprises a first lens unit G1 having negative power, a second lens unit G2 having positive power and a third lens unit G3 having positive power, wherein magnification is varied with change in intervals between each lens unit by independently moving each lens unit along an optical axis, in which the first lens unit G1 comprises one negative lens element L1 and one positive lens element L2, the second lens unit G2 comprises only a cemented lens element having set of three lens elements L3, L4 and L5 which are cemented with each other, and the third lens unit G3 comprises one positive lens element L6.

Abstract: It is an object to provide a zoom lens made of three groups having a zoom ratio of ×2.5 to ×3.2 if the object distance is ?, an field angle at the wide-angle end of 60° to 70°, high resolution, and a short optical total length when not in use. The zoom lens is made of a first lens group (G1) with a negative power, a second lens group (G2) with a positive power, and a third lens group (G3) with a positive power, arranged in that order from an object side to an image plane (S) side. The first lens group (G1) is made of a first lens (L1) that is a negative meniscus lens whose surface with strong curvature is facing the image plane (S) side and a second lens (L2) that is a positive meniscus lens whose surface with strong curvature is facing the object side, arranged in that order from the object side.