Multi-cameras and in particular dual-cameras comprising a Wide camera comprising a Wide lens and a Wide image sensor, the Wide lens having a Wide effective focal length EFL.sub.W and a folded Tele camera comprising a Tele lens with a first optical axis, a Tele image sensor and an OPFE, wherein the Tele lens includes, from an object side to an image side, a first lens element group G1, a second lens element group G2 and a third lens element group G3, wherein at least two of the lens element groups are movable relative to the image sensor along the first optical axis to bring the Tele lens to two zoom states, wherein an effective focal. length (EFL) of the Tele lens is changed from EFL.sub.T,min in one zoom state to EFL.sub.T,max in the other zoom state, wherein EFL.sub.Tmin>1.5×EFL.sub.W and wherein EFL.sub.Tmax>1.5×EFL.sub.Tmin.

A lens system is provided. The lens system includes a positive first lens group, an aperture diaphragm, a positive second lens group, and a third lens group, disposed sequentially from a subject side. The first lens group includes at least three positive lenses and at least one negative lens. The second lens group includes four or more lenses including at least one cemented lens. A negative lens with a concave surface toward the subject side is disposed at the subject side. The third lens group includes three or more lenses including at least one positive lens and at least one negative lens. When focusing is moving from an infinity-distance subject to a short-distance subject, the first lens group, the aperture diaphragm, and the second lens group move integrally toward the subject side, while the third lens group is fixed with respect to an image surface.

Multi-cameras and in particular dual-cameras comprising a Wide camera comprising a Wide lens and a Wide image sensor, the Wide lens having a Wide effective focal length EFL.sub.W and a folded Tele camera comprising a Tele lens with a first optical axis, a Tele image sensor and an OPFE, wherein the Tele lens includes, from an object side to an image side, a first lens element group G1, a second lens element group G2 and a third lens element group G3, wherein at least two of the lens element groups are movable relative to the image sensor along the first optical axis to bring the Tele lens to two zoom states, wherein an effective focal length (EFL) of the Tele lens is changed from EFL.sub.T,min in one zoom state to EFL.sub.T,max in the other zoom state, wherein EFL.sub.Tmin>1.5×EFL.sub.W and wherein EFL.sub.Tmax>1.5×EFL.sub.Tmin.

A zoom optical system (ZL) comprises: a first lens group (G1) disposed closest to an object and having a positive refractive power; an aperture stop (S) disposed closer to an image than the first lens group (G1); a positive lens component disposed so as to oppose the image side of the aperture stop (S); and a lens group (G3) having the positive lens component, wherein a distance between the first lens group (G1) and the lens group (G3) having the positive lens component changes during zooming, at least one lens surface of the positive lens component has an aspherical surface, and the following conditional expression,

0.40<fp/fGp<3.60

is satisfied,
where fp: a focal length of the positive lens component, and fGp: a focal length of the lens group (G3) having the positive lens component.

Multi-cameras and in particular dual-cameras comprising a Wide camera comprising a Wide lens and a Wide image sensor, the Wide lens having a Wide effective focal length EFL.sub.W and a folded Tele camera comprising a Tele lens with a first optical axis, a Tele image sensor and an OPFE, wherein the Tele lens includes, from an object side to an image side, a first lens element group G1, a second lens element group G2 and a third lens element group G3, wherein at least two of the lens element groups are movable relative to the image sensor along the first optical axis to bring the Tele lens to two zoom states, wherein an effective focal length (EFL) of the Tele lens is changed from EFL.sub.T,min in one zoom state to EFL.sub.T,max in the other zoom state, wherein EFL.sub.Tmin>1.5×EFL.sub.W and wherein EFL.sub.Tmax>1.5×EFL.sub.Tmin.

An image formation optical system includes a first optical system, in which a first refractive system is arranged toward the reduction side of an intermediate image and a second refractive system is arranged toward the magnification side of the intermediate image, and the first refractive system has a first stop, and the second refractive system has a second stop. Lens surfaces are arranged next to and both toward the reduction side and toward the magnification side of the first stop and the second stop, and the following condition is satisfied:

1.5<Y1-1 (unit of mm), where Y1-1 is the absolute value of the ray height of a principal ray at an outermost angle of view in rays emitted from a lens surface arranged next to and toward the reduction side of the first stop.

An imaging lens comprises in order from an object, a first lens group of positive refractive power, a second lens group of positive refractive power, and a third lens group of negative refractive power. In focusing from infinity to a close object, the first lens group is fixed in position, and the second lens group and the third lens group are moved so that the distance between the first lens group and the second lens group is reduced, and the distance between the second lens group and the third lens group is increased. Further, the following conditional expression (1) is satisfied:
1.0<f1/f<2.5  (1) where f1: is the focal length of the first lens group, and f: the focal length of the entire system.

An optical system 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 positive refractive power, and a third lens unit having a negative refractive power. The second lens unit moves during focusing and a distance between adjacent lens units changes. The second lens unit includes a cemented lens closest to an object. The cemented lens includes a positive lens and a negative lens disposed on the image side of the positive lens. A predetermined condition is satisfied.

Folded Tele cameras comprising an optical path folding element (OPFE) for folding a first optical path OP1 to a second optical path OP2, a lens including N=8 lens elements, the lens being divided into three lens groups numbered, in order from an object side of the lens, G1, G2 and G3, and an image sensor, wherein G1 and G3 are included in a single G13 carrier, wherein G2 is included in a G2 carrier, wherein both the G13 carrier and the G2 carrier include rails for defining the position of G2 relative to G13, wherein the Tele camera is configured to change a zoom factor continuously between a minimum zoom factor ZF.sub.MIN and a maximum zoom factor ZF.sub.MAX by moving the G2 carrier relative to the G13 carrier and by moving the G13 carrier relative to the image sensor, and wherein an effective focal length (EFL) is 7.5 mm<EFL<50 mm. The G2 carrier may be positioned by a lens transporter within the G13 carrier at a particular zoom factor to form a lens pair to enable optical investigation and/or transporting of the lens pair.

Multi-cameras and in particular dual-cameras comprising a Wide camera comprising a Wide lens and a Wide image sensor, the Wide lens having a Wide effective focal length EFL.sub.W and a folded Tele camera comprising a Tele lens with a first optical axis, a Tele image sensor and an OPFE, wherein the Tele lens includes, from an object side to an image side, a first lens element group G1, a second lens element group G2 and a third lens element group G3, wherein at least two of the lens element groups are movable relative to the image sensor along the first optical axis to bring the Tele lens to two zoom states, wherein an effective focal length (EFL) of the Tele lens is changed from EFL.sub.T,min in one zoom state to EFL.sub.T,max in the other zoom state, wherein EFL.sub.Tmin>1.5×EFL.sub.W and wherein EFL.sub.Tmax>1.5×EFL.sub.Tmin.