Abstract: The zoom lens according to the present invention includes in order from an object side to an image side: a first lens unit; a second lens unit; a third lens unit; an aperture stop; and a fourth lens unit; wherein a partial dispersion ratio ?Lm of a material of a positive lens Lm formed of a material having a highest partial dispersion ratio, which is contained in a rear group, a distance d from the aperture stop to an image plane, a distance dLm from the aperture stop to a positive lens Lm, an average value ?Rfp of Abbe constants of materials of positive lenses contained in a front group, an average value ?Rfp of partial dispersion ratios thereof, an average value ?Rfn of Abbe constants of materials of negative lenses contained in the front group, and an average value ?Rfn of partial dispersion ratios thereof are each appropriately set.

Abstract: A zoom lens include, from an object side: a positive first unit that does not move for zooming; a negative second unit that moves during zooming; a negative third unit that moves during zooming; a positive fourth unit that moves during zooming; and a positive fifth unit, wherein the second unit moves towards the image side during zooming towards a telephoto end, the third unit moves towards the object side during focus adjustment towards a close distance, and a focal length of the zoom lens at the wide angle end, a zoom ratio, a focal length of the zoom lens at a zoom position where the third unit is closest to the object, a focal length of the first unit, a focal length of the second unit, a focal length of the third unit, and a focal length of the fourth unit are appropriately set.

Abstract: The zoom lens according to the present invention includes in order from an object side to an image side: a first lens unit; a second lens unit; a third lens unit; an aperture stop; and a fourth lens unit; wherein a partial dispersion ratio ?Lm of a material of a positive lens Lm formed of a material having a highest partial dispersion ratio, which is contained in a rear group, a distance d from the aperture stop to an image plane, a distance dLm from the aperture stop to a positive lens Lm, an average value ?Rfp of Abbe constants of materials of positive lenses contained in a front group, an average value ?Rfp of partial dispersion ratios thereof, an average value ?Rfn of Abbe constants of materials of negative lenses contained in the front group, and an average value ?Rfn of partial dispersion ratios thereof are each appropriately set.

Abstract: The ranging apparatus of the present invention measures the distance to an object to be imaged by an imaging apparatus using the principle of triangulation ranging, and has a measurement unit in which a maximum distance that can be ranged to an object is not less than ½ of a maximum value of the hyper focal length of the imaging apparatus.

Abstract: A zoom lens, including: a front lens group; an aperture stop; and a rear lens group, in which the rear lens group includes: a front lens unit and a rear lens unit, a maximum air interval of the rear lens group being interposed between the front lens unit and the rear lens unit, in which the rear lens unit includes: a first lens which is located on the most object side; a second lens which is located on the most image side, and the following conditional expressions are satisfied: ?6.0?fs1/frr??1.0; and ?9.0?fs3/frr??2.0, where frr indicates a focal length of the rear lens unit, and fs1 and fs3 indicate a focal length of the first lens and a focal length of the second lens, respectively.

Abstract: A zoom lens, including: a first lens unit and a second lens unit, in which the first lens unit includes: a first lens sub unit which does not move; a second lens sub unit which moves for focusing; and a third lens sub unit which does not move; and in which the following expression is satisfied, ?2.27×10?3<(?p??na)/(?p??na)<?1.9×10?3, where ?na and ?na represent an average value of an Abbe number ? and an average value of a partial dispersion ratio ? of negative lenses included in the first lens sub unit, respectively, ?p and ?p represent an Abbe number and a partial dispersion ratio of a positive lens having a smallest Abbe number among lenses constituting the first lens sub unit, respectively, ?=(Ng?NF)/(NF?NC), and Ng, NF and NC denote refractive indexes at the g-line, the F-line and a C-line, respectively.

Abstract: The ranging apparatus of the present invention measures the distance to an object to be imaged by an imaging apparatus using the principle of triangulation ranging, and has a measurement unit in which a maximum distance that can be ranged to an object is not less than ½ of a maximum value of the hyper focal length of the imaging apparatus.

Abstract: A zoom lens, including: a first lens unit and a second lens unit, in which the first lens unit includes: a first lens sub unit which does not move; a second lens sub unit which moves for focusing; and a third lens sub unit which does not move; and in which the following expression is satisfied, ?2.27×10?3<(?p??na)/(?p??na)<?1.9×10?3, where ?na and ?na represent an average value of an Abbe number ? and an average value of a partial dispersion ratio ? of negative lenses included in the first lens sub unit, respectively, ?p and ?p represent an Abbe number and a partial dispersion ratio of a positive lens having a smallest Abbe number among lenses constituting the first lens sub unit, respectively, ?=(Ng?NF)/(NF?NC), and Ng, NF and NC denote refractive indexes at the g-line, the F-line and a C-line, respectively.

Abstract: A zoom lens, including: a front lens group; an aperture stop; and a rear lens group, in which the rear lens group includes: a front lens unit and a rear lens unit, a maximum air interval of the rear lens group being interposed between the front lens unit and the rear lens unit, in which the rear lens unit includes: a first lens which is located on the most object side; a second lens which is located on the most image side, and the following conditional expressions are satisfied: ?6.0?fs1/frr??1.0; and ?9.0?fs3/frr??2.0, where frr indicates a focal length of the rear lens unit, and fs1 and fs3 indicate a focal length of the first lens and a focal length of the second lens, respectively.

Abstract: A zoom lens system includes four lens units each having positive, negative, negative and positive refractive powers in the stated order from an object side to an image side. A first lens unit includes a variable apex angle prism on the image side of at least one lens element. In this zoom lens system, a focal length of the first lens unit and imaging magnifications of a second lens unit and a fourth lens unit are set appropriately so as to suppress occurrence of decentering aberration accompanying a variation of a prism apex angle.

Abstract: A zoom lens system includes, in order from the object side to the image side, four lens units having positive, negative, negative and positive refractive powers. A first lens unit includes, in order from the object side to the image side: a front subunit having a negative refractive power; a middle subunit that has a positive refractive power and moves during focusing; and a rear subunit having a positive refractive power. The zoom lens system further includes a variable apex angle prism disposed on the image side of the front subunit. An average Abbe number of materials of a negative lens element and a positive lens element included in the front subunit is set appropriately so as to suppress occurrence of decentering aberration accompanying a variation of a prism apex angle.

Abstract: A zoom lens system includes, in order from the object side to the image side, four lens units having positive, negative, negative and positive refractive powers. A first lens unit includes, in order from the object side to the image side: a front subunit having a negative refractive power; a middle subunit that has a positive refractive power and moves during focusing; and a rear subunit having a positive refractive power. The zoom lens system further includes a variable apex angle prism disposed on the image side of the front subunit. An average Abbe number of materials of a negative lens element and a positive lens element included in the front subunit is set appropriately so as to suppress occurrence of decentering aberration accompanying a variation of a prism apex angle.

Abstract: A zoom lens system includes four lens units each having positive, negative, negative and positive refractive powers in the stated order from an object side to an image side. A first lens unit includes a variable apex angle prism on the image side of at least one lens element. In this zoom lens system, a focal length of the first lens unit and imaging magnifications of a second lens unit and a fourth lens unit are set appropriately so as to suppress occurrence of decentering aberration accompanying a variation of a prism apex angle.