A zoom lens system includes a positive first lens group, a negative second lens group, a positive intermediate lens group, and a negative image-side lens group. Upon zooming from the short to long focal length extremities, a distance between the first and second lens groups increases, and a distance between the second and intermediate lens groups decreases. The image-side lens group consists of two lens elements. The following conditions are satisfied:

−6.0<f1/f2<−4.3,

−5.4<f1/fIMG<−3.9,

and

0.3<D2/fw<3.0.

f1, f2 and fIMG designate the focal lengths of the first, second and the image-side lens groups, respectively. D2 designates a distance between the second lens group and the intermediate lens group, at the short focal length extremity. fw designates the focal length of the zoom lens system at the short focal length extremity.

A camera lens module in which an optical system is configured to include five sheets of lenses is provided. In the camera lens module, first, second, third, fourth and fifth lenses are sequentially arranged from an object side, and the first lens performs a zooming operation while moving along an optical axis. Accordingly, the optical system is configured to include five sheets of lenses for performance of a zooming operation and to allow only the first lens to perform the zooming operation, so that it is possible to manufacture a high-resolution optical system in a compact size and to perform the zooming operation at a high speed.

Provided is a zoom lens including, in order from an object side: a first lens unit not moving for zooming; a second lens unit moving during the zooming; at least one lens unit moving during the zooming; and a rear lens group. The first lens unit includes a first lens sub unit not moving for focusing, and a second lens sub unit moving during the focusing. The first lens sub unit includes a negative lens and a positive lens. A focal length of the first lens unit, a distance on an optical axis from a lens surface closest to an image side of the first lens sub unit to a rear principal point position of the first lens sub unit, and a focal length of the zoom lens at a telephoto end are appropriately set.

An optical system (LS) has a lens (L11) that satisfies the following conditional expressions.

−0.010<ndLZ−(2.015−0.0068×νdLZ)

50.00<νdLZ<65.00 0.545<θgFLZ

−0.010<θgFLZ−(0.6418−0.00168×νdLZ) where ndLZ is the refractive index to the d line of the lens, νdLZ is the Abbe number with respect to the d line of the lens, and θgFLZ is the partial dispersion ratio of the lens.

This optical system (LS) has an aperture diaphragm (S) and a negative lens (L4) disposed closer to an object side than the aperture diaphragm (S) and satisfies the following conditional expression.

−0.010<ndN1−(2.015−0.0068×νdN1),

50.00<νdN1<65.00, 0.545<θgFN1,

−0.010<θgFN1−(0.6418−0.00168×νdN1).

Where, ndN1 is a refractive index of the negative lens with respect to a d-line, vdN1 is an Abbe number of the negative lens based on the d-line, and θgFN1 is a partial dispersion ratio of the negative lens.

There is provided a zoom lens, consisting of sequentially from an object side: a first lens group having a positive refractive power and a focusing function; a second lens group having a negative refractive power and having a variator function of performing zooming; a third lens group having a positive refractive power and a diaphragm; a fourth lens group having a positive refractive power, and having a compensator function of correcting a position of an imaging plane at the time of zooming; and a fifth lens group having a positive or negative refractive power, wherein the second lens group is moved to the imaging plane side from the object side along an optical axis, and the fourth lens group is moved along the optical axis in a state of fixing the first lens group, the third lens group, and the fifth lens group at the time of zooming from a wide angle end to a telephoto end, and only the first lens group is moved along the optical axis at the time of focusing.

A first lens group (G1) having positive refractive power, a front-side lens group (GX), an intermediate lens group (GM) having positive refractive power, and a rear-side lens group (GR) are arranged in order from an object side. The front-side lens group (GX) is composed of one or more lens groups and has a negative lens group At least part of the intermediate lens group (GM) is a focusing lens group (GF). The rear-side lens group (GR) is composed of one or more lens groups. Upon zooming, the first lens group (G1) is moved with respect to an image surface, a distance between the first lens group (G1) and the front-side lens group (GX) is changed, a distance between the front-side lens group (GX) and the intermediate lens group (GM) is changed, and a distance between the intermediate lens group (GM) and the rear-side lens group (GR) is changed.

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 having positive refractive power; upon varying a magnification, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the rear lens group being varied; the rear lens group comprising a focusing lens group which is moved upon carrying out focusing from an infinitely distant object to a closely distant object; and predetermined conditional expression(s) being satisfied, thereby various aberrations being corrected superbly.

A camera optical lens includes first to seventh lenses that are sequentially arranged from an object side to an image side. Each of the first lens, the third lens, and the fourth lens has a positive refractive power, and each of the second lens and the fifth lens has a negative refractive power. The camera optical lens satisfies: 0.50≤f1/f≤0.80; −1.20≤f2/f≤−0.70; 1.50≤d8/d9≤3.00; −1.50≤R3/R4≤−0.60; and 1.20≤R7/R8≤2.00, where f denotes a focal length of the camera optical lens; f1 denotes a focal length of the first lens; f2 denotes a focal length of the second lens; and d8 denotes an on-axis distance from an image-side surface of the fourth lens to an object-side surface of the fifth lens. The camera optical lens can achieve high optical performance while satisfying design requirements for being ultra-thin and having a wide-angle and a large apertures.

The present invention discloses a portable zoom microscope, comprising a case (15) and an optical system assembly installed in the case (15), characterized in that the optical system assembly comprises an objective I (1), an objective II (2), an eyepiece III (3), an eyepiece II (4) and an eyepiece I (5) arranged in sequence along an optical axis Z from an object plane to eyes, wherein the objective I (1) is a positive lens, the objective II (2) is a negative lens, the eyepiece III (3) is a positive lens, the eyepiece II (4) is a positive lens, and the eyepiece I (5) is a negative lens, which effectively eliminates the longitudinal chromatic aberration and the lateral colour, so that the zoom microscope can distinguish the details of small objects more clearly and intuitively, greatly improving the image quality of products.