A zoom optical system comprises, in order from an object side: a first lens group having positive refractive power; a front-side lens group; an intermediate lens group having positive refractive power; and a rear-side lens group. The front-side lens group is composed of one or more lens groups and has a negative lens group. At least part of the intermediate lens group is a focusing lens group. The rear-side lens group is composed of one or more lens groups. Upon zooming, the first lens group is moved with respect to an image surface and distances between the first lens group and the front-side lens group, between the front-side lens group and the intermediate lens group, and between the intermediate lens group and the rear-side lens group change. The following conditional expressions are satisfied:

−0.750<fF/fRF<4.000

2.250<TLW/ZD1<5.000

32.000≤Wω

where fF denotes a focal length of the focusing lens group, fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group, TLW denotes an entire length of the optical system in a wide angle end state, ZD1 denotes a movement amount of the first lens group upon zooming from the wide angle end state to a telephoto end state, and Wω denotes a half angle of view in the wide angle end state.

A variable magnification optical system includes a positive first lens group disposed at a most object side, a negative intermediate group disposed at an image side of the first lens group, a positive focusing group disposed at an image side of the intermediate group, and a positive image side group disposed at an image side of the focusing group. Upon varying magnification, a distance between the first lens group and the intermediate group, a distance between the intermediate group and the focusing group and a distance between the focusing group and the image side group are varied; and the image side group includes, in order from an object side, a positive A group, a negative B group satisfying a predetermined conditional expression with respect to the A group, and a C group, whereby excellent optical performance, high speed focusing, and other advantages are achieved.

An optical system (LS) has an aperture stop (S), and a negative lens (L73) disposed closer to the image side than the aperture stop (S) and satisfying the following conditional expressions.

−0.010<ndN2−(2.015−0.0068×νdN2),

50.00<νdN2<65.00,

0.545<θgFN2,

−0.010<θgFN2−(0.6418−0.00168×νdN2)

where ndN2 is the refractive index to the d line of the negative lens, νdN2 is the Abbe number with respect to the d line of the negative lens, and θgFN2 is the partial dispersion ratio of the negative lens.

A first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, a fourth lens group (G4) having positive refractive power, a fifth lens group (G5) are arranged in order from an object, and a distance between the first lens group (G1) and the second lens group (G2), a distance between the second lens group (G2) and the third lens group (G3), a distance between the third lens group (G3) and the fourth lens group (G4), and a distance between the fourth lens group (G4) and the fifth lens group (G5) change upon zooming, and a lens group arranged closest to an image is approximately fixed against an image surface (I) upon zooming, and the third lens group (G3) moves along the optical axis upon focusing, and the following expression (1) is satisfied.
0.480<f3/ft<4.000   (1)

A variable magnification optical system comprising, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear lens group; upon varying magnification, the first lens group being fixed with respect to the image plane and each distance between the neighboring lens groups being varied; the rear lens group comprising a focusing lens group which is moved upon carrying out focusing; and the predetermined conditional expressions being satisfied, whereby it is possible to suppress superbly variations in aberrations upon varying the magnification.

A zoom lens 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, a third lens unit with a positive refractive power, and a fourth lens unit with a positive refractive power. During zooming from a wide-angle end to a telephoto end, the first lens unit moves, the second lens unit is fixed, a distance between the first lens unit and the second lens unit is widened, a distance between the second lens unit and the third lens unit is narrowed, and a distance between the third lens unit and the fourth lens unit is narrowed. The first lens unit includes a positive lens and a negative lens. Each of the second, third, and fourth lens units consists of two lenses or less.

An optical zoom camera and an optical zoom system for the optical zoom camera. The optical zoom system comprises at least three spatially separated lens groups, which are arranged on an optical axis. The optical zoom system does not include any further lens groups on the optical axis. A third lens group is immovable along the optical axis, a second lens group is movable along the optical axis to set a magnification of the optical zoom system, and a first lens group is movable along the optical axis to focus the optical zoom system.

A camera optical lens includes first to fifth lenses from an object side to an image side, the first, third, and fourth lenses having positive refractive power, the second and fifth lenses having negative refractive power, and satisfies: −6.00≤f2/f≤−3.00; −20.00≤(R7+R8)/(R7−R8)≤−2.00; and 1.60≤d2/d4≤6.00, where f denotes focal length of the camera optical lens, f2 denotes focal length of the second lens, R7 denotes central curvature radius of an object side surface of the fourth lens, R8 denotes central curvature radius of an image side surface of the fourth lens, d2 denotes on-axis distance from an image side surface of the first lens to an object side surface of the second lens, and d4 denotes on-axis distance from an image side surface of the second lens to an object side surface of the third lens, thereby having good optical performance while meeting design requirements of a wide angle and ultra-thinness.

Comprising a positive first lens group G1 disposed at a most object side, a negative intermediate group G2 disposed at an image side of the first lens group G1, a positive focusing group G3 disposed at an image side of the intermediate group G2, the focusing group G3 being moved upon focusing, and a positive image side group G4 disposed at an image side of the focusing group G3; upon varying magnification, a distance between the first lens group G1 and the intermediate group G2, a distance between the intermediate group G2 and the focusing group G3 and a distance between the focusing group G3 and the image side group G4 being varied; and a predetermined conditional expression being satisfied. Whereby a variable magnification optical system having excellent optical performance and a focusing lens group reduced in weight in order to attain high speed focusing operation, and others are provided.

A zoom lens including, in order from object side to image side, first to fourth lens units respectively having positive, negative, positive, and positive refractive powers. During zooming from a wide-angle end to a telephoto end, the first lens unit is arranged to move, the distance between the first lens unit and the second lens unit increases, the distance between the second lens unit and the third lens unit decreases, and the distance between the third lens unit and the fourth lens unit decreases. The second lens unit consists of a first lens having a negative refractive power and a second lens having a positive refractive power, the second lens being disposed on the image side of the first lens. A predetermined condition is satisfied.