A zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group which are sequentially disposed in a direction from an object side to an image side, wherein the second lens group and the third lens group are movable, a total track length (TTL) is less than 20 mm, and an effective focal length (EFL) in a telephoto is greater than 25 mm.

Embodiments of this application provide a lens group, a camera module, and a terminal device. The lens group includes a first group, a second group, a third group, and a fourth group that are sequentially disposed from an object side to an image side along an optical axis of the lens group. The second group includes a doublet formed by gluing a second lens and a third lens together. The optical power of a lens in each group is designed to match the optical power of the doublet so that a compact high-quality long-focus lens group can be implemented and chromatic aberration may be eliminated.

A zoom optical system according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, and a fourth lens group which are sequentially arranged in a direction from a subject side to an image side, wherein the second lens group and the third lens group are movable, and an effective focal length (EFL) in a telephoto mode is defined by an expression below.

[00001]$11.5<\frac{{\mathrm{EFL}}_{\mathrm{tele}}}{H_{\mathrm{imageD}}}<12.5$

Here, EFL.sub.tele is the EFL of the zoom optical system in the telephoto mode, and tele H.sub.imageD is a half value of a diagonal length of a pixel area of an image sensor.

The invention discloses a lamp with a zoom lens, which comprises the zoom lens and a lamp body, the lamp body is connected with the zoom lens, the zoom lens comprises: a rear fixed group, comprising a first biconvex lens; a zooming group, comprising a first concave-convex meniscus lens and a plano-convex lens; a compensating group, comprising a biconcave meniscus lens and a second concave-convex meniscus lens; and a front fixed group, comprising a second biconvex lens. The four groups are sequentially arranged in the direction of an optical axis; and the lamp realizes zooming by movement of the zooming group and the compensating group in the direction of the optical axis. A change of a pattern or a beam size is realized; the number of lenses is reduced; zooming of the zoom lens is realized only by movement of the zooming group and the compensating group.

A zoom optical system according to an embodiment of the present invention comprises a first lens group, a second lens group, a third lens group, and a fourth lens group which are sequentially arranged in a direction from a subject side to an image side, wherein each of the first lens group to the fourth lens group includes at least two lenses, the second lens group and the third lens group are movable, and an effective focal length (EFL) in a wide angle mode is defined by an expression below.

[00001]$5.5<\frac{{\mathrm{EFL}}_{\mathrm{wide}}}{H_{\mathrm{image}D}}<6.5.$

Here, EFL.sub.wide is the EFL of the zoom optical system in the wide angle mode, and H.sub.imageD is a half value of a diagonal length of a pixel area of an image sensor.

A lens interchangeable digital camera includes an image sensor in which a subject image is formed on an imaging surface through an imaging optical system including a zoom lens and a sensor movement type shake correction mechanism that performs a sensor movement operation of moving the image sensor in a direction to cancel a shake. A zoom operation determination unit determines whether or not a zoom operation in which the zoom lens moves is being performed. In a case where the zoom operation determination unit determines that the zoom operation is being performed, an operation deciding unit prohibits a shift operation which is at least a part of a sensor movement operation which is allowed while the zoom operation is stopped.

An image lens assembly includes, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. A total number of lens elements in the image lens assembly is seven. The first lens group includes a first lens element with positive refractive power and a second lens element with negative refractive power. Each of the second lens group and the third lens group includes at least one lens element. The fourth lens group includes a seventh lens element. When the image lens assembly is focusing or zooming, a relative position between the first lens group and an image surface is fixed, a relative position between the fourth lens group and the image surface is fixed, and the second lens group and the third lens group move along the optical axis.

The imaging lens includes, in order from a position closest to an object side to an image side: a front lens group that has a positive refractive power and is immovable during focusing; a stop that is disposed subsequent to the front lens group; a first focus lens group that has a positive refractive power; a second focus lens group that has a negative refractive power; and a final lens group that has a positive refractive power, is disposed closest to the image side, and is immovable during focusing. During focusing from an infinite distance object to a short range object, the first focus lens group and the second focus lens group move to increase a mutual distance therebetween.

The invention discloses a lamp with a zoom lens, which comprises the zoom lens and a lamp body, the lamp body is connected with the zoom lens, the zoom lens comprises: a rear fixed group, comprising a first biconvex lens; a zooming group, comprising a first concave-convex meniscus lens and a plano-convex lens; a compensating group, comprising a biconcave meniscus lens and a second concave-convex meniscus lens; and a front fixed group, comprising a second biconvex lens. The four groups are sequentially arranged in the direction of an optical axis; and the lamp realizes zooming by movement of the zooming group and the compensating group in the direction of the optical axis. A change of a pattern or a beam size is realized; the number of lenses is reduced; zooming of the zoom lens is realized only by movement of the zooming group and the compensating group.

The present embodiment discloses an interchangeable lens that can be detachably attached to an apparatus body having an image forming surface on which an image is formed, and the interchangeable lens has a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side. The interchangeable lens includes a focus lens group that can move along an optical axis to adjust a focus at the magnification conjugate point and a flange back distance correction lens group that can move along the optical axis to correct an error in a flange back distance of the interchangeable lens with respect to the image forming surface.