Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including at least two lens units and having a positive refractive power as a whole, in order from an object side to an image side. An interval of each of the lens units changes in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side, the lens unit R includes a lens having a concave surface at the image side and having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and focal lengths f1, fR, and fw of the first lens unit, the lens unit R, and a whole system at a wide-angle end, respectively, are appropriately set.

Abstract: A nonvolatile semiconductor memory device includes a first string including a first number of memory cells connected in series each storing therein information in a nonvolatile manner; and a second string including a second number of memory cells connected in series each storing therein information in a nonvolatile manner, wherein the second number is smaller than the first number.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear lens group including lens units and as a whole having a positive refractive power. Distances between the lens units change during zooming. The second lens unit includes, in order from the object side to the image side, a negative lens component and a cemented lens including a negative lens component and a positive lens component. The second lens unit includes at least five lens components. A focal length f1 of the first lens unit, a focal length f2 of the second lens unit, a refractive index Ndp of the positive lens component of the cemented lens, and a refractive index Ndn of the negative lens component of the cemented lens are set appropriately.

Abstract: An optical system (OL) includes a magnification conversion optical unit (EXT) configured to be insertable and removable at a position between an aperture stop (SP) and an image plane (IP) of the optical system in order to change a focal length of the optical system, a total lens length of the optical system is constant before and after insertion of the magnification conversion optical unit, and a length Lp on an optical axis from the aperture stop to the image plane of the optical system, and a length Le on the optical axis from a lens surface closest to an object side of the magnification conversion optical unit to the image plane when the magnification conversion optical unit is inserted are appropriately set.

Abstract: A nonvolatile semiconductor memory device includes a first string including a first number of memory cells connected in series each storing therein information in a nonvolatile manner; and a second string including a second number of memory cells connected in series each storing therein information in a nonvolatile manner, wherein the second number is smaller than the first number.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including at least two lens units and having a positive refractive power as a whole, in order from an object side to an image side. An interval of each of the lens units changes in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side, the lens unit R includes a lens having a concave surface at the image side and having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and focal lengths f1, fR, and fw of the first lens unit, the lens unit R, and a whole system at a wide-angle end, respectively, are appropriately set.

Abstract: A nonvolatile semiconductor memory device includes a first string including a first number of memory cells connected in series each storing therein information in a nonvolatile manner; and a second string including a second number of memory cells connected in series each storing therein information in a nonvolatile manner, wherein the second number is smaller than the first number.

Abstract: An optical system includes a first lens unit, an aperture stop, and a second lens unit having a positive refractive power. In the optical system, the first lens unit includes at least one positive lens made of a material whose Abbe number (?dGP) and relative partial dispersion (?gFGP) satisfy a predetermined condition.

Abstract: A zoom lens comprises a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear group including at least two lens units and having a positive refractive power as a whole, in order from an object side to an image side. An interval of each of the lens units changes in a zoom operation, the rear group includes a lens unit R having a positive refractive power at the most image side, the lens unit R includes a lens having a concave surface at the image side and having an aspherical surface shape where a negative refractive power becomes stronger with increasing distance from an optical axis, and focal lengths f1, fR, and fw of the first lens unit, the lens unit R, and a whole system at a wide-angle end, respectively, are appropriately set.

Abstract: An optical system includes a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. The second lens unit includes a front lens unit, a stop, and a rear lens unit. The front lens unit includes a biconvex positive lens located closest to the image side. A back focus during focusing on an infinitely-distant object point (BF), a focal length of the entire optical system (f), a focal length of the positive lens of the front lens unit located closest to the image side (fp), a focal length of the front lens unit (f2a), a refractive power of a surface of the rear lens unit located closest to the object side (?f), and a refractive power of the entire optical system (?) satisfy the following conditions: 1.0<BF/f<3.0 0.1<fp/f2a<0.5 0.7<|?f/?|<1.5.

Abstract: An optical system includes a first lens unit, an aperture stop, and a second lens unit having a positive refractive power. In the optical system, the first lens unit includes at least one positive lens made of a material whose Abbe number (?dGP) and relative partial dispersion (?gFGP) satisfy a predetermined condition.

Abstract: A zoom lens includes, in order from object to image sides, first and second lens units having positive and negative refractive power, respectively, and a rear lens group including at least one lens unit having positive refractive power. The rear lens group includes a lens unit IS having negative refractive power and movable in a direction having a component perpendicular to an optical axis so as to displace an imaging position, and a lens unit R_IS having positive refractive power and arranged on the image side of the lens unit IS. The distance between the lens units IS and R_IS is varied during zooming. The following conditions are satisfied: 0.05<|fIS/fT|<0.18 2.0<f1/fR—IS<4.5 where fIS, fT, f1, and fR_IS are focal lengths of the lens unit IS, entire zoom lens at a telephoto end, first lens unit, and lens unit R_IS, respectively.

Abstract: An optical system includes a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. The second lens unit includes a front lens unit, a stop, and a rear lens unit. The front lens unit includes a biconvex positive lens located closest to the image side. A back focus during focusing on an infinitely-distant object point (BF), a focal length of the entire optical system (f), a focal length of the positive lens of the front lens unit located closest to the image side (fp), a focal length of the front lens unit (f2a), a refractive power of a surface of the rear lens unit located closest to the object side (?f), and a refractive power of the entire optical system (?) satisfy the following conditions: 1.0<BF/f<3.0 0.1<fp/f2a<0.5 0.7<|?f/?|<1.5.

Abstract: A zoom lens includes, in order from the object side to the image side, 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. The first lens unit and the third lens unit move in the optical axis direction during zooming. The following conditions are satisfied: 0.60<m3/m1<0.90, and 0.080<|f2/ft|<0.120, where m1 and m3 are maximum moving distances in the optical axis direction of the first lens unit and the third lens unit, respectively, during zooming from the wide-angle end to the telephoto end, ft is a focal length of the zoom lens at the telephoto end, and f2 is a focal length of the second lens unit.

Abstract: A zoom lens includes, in order from object to image sides, first and second lens units having positive and negative refractive power, respectively, and a rear lens group including at least one lens unit having positive refractive power. The rear lens group includes a lens unit IS having negative refractive power and movable in a direction having a component perpendicular to an optical axis so as to displace an imaging position, and a lens unit R_IS having positive refractive power and arranged on the image side of the lens unit IS. The distance between the lens units IS and R_IS is varied during zooming. The following conditions are satisfied: 0.05<|fIS/fT|<0.18 2.0<f1/fR_IS<4.5 where fIS, fT, f1, and fR_IS are focal lengths of the lens unit IS, entire zoom lens at a telephoto end, first lens unit, and lens unit R_IS, respectively.

Abstract: A zoom lens includes, in order from the object side to the image side, 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. The first lens unit and the third lens unit move in the optical axis direction during zooming. The following conditions are satisfied: 0.60<m3/m1<0.90, and 0.080<|f2/ft|<0.120, where m1 and m3 are maximum moving distances in the optical axis direction of the first lens unit and the third lens unit, respectively, during zooming from the wide-angle end to the telephoto end, ft is a focal length of the zoom lens at the telephoto end, and f2 is a focal length of the second lens unit.