JP2007316287A - Zoom lens and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens having a wide view angle and a high zoom ratio, and capable of obtaining high optical performance over the entire zoom area, and to provide an imaging apparatus having the zoom lens. <P>SOLUTION: The zoom lens includes, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, wherein the second and fourth lens groups move when zooming. The first lens group is composed of: one or more negative lenses that have a concave face on the image side; a lens that has a concave face on the image side; one or more positive lenses that are convex on both sides; and a cemented lens or negative lens consisting of a negative lens and a positive lens; and a positive lens disposed closest to an image, having the absolute value of refractive force that is greater on the object side than on the image side, and having a convex face on the image side. The composite focal distance f1FF of one or more negative lenses of the first lens group, which have a concave face on the image side, a lens that has a concave face on the image side, and one or more positive lenses that are convex on both sides, and the focal distance f1 of the first lens group are appropriately set. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zoom lens and an imaging apparatus using the same, and is suitably used for electronic cameras such as video cameras and digital still cameras, film cameras, broadcast cameras, and the like.

  Recently, imaging devices (cameras) such as a video camera, a digital still camera, and a surveillance camera using a solid-state imaging device are required to have high functionality and to be small in size as a whole.

  Accordingly, an optical system (imaging optical system) used for these cameras is required to be a zoom lens having a small size, a wide angle of view, and high optical performance.

  Further, in an imaging apparatus using a color separation optical system such as a prism or a filter, these color separation optical systems are arranged on the image side. For this reason, the zoom lens used for these is required to have a back focus having a length corresponding to the optical path length of the color separation optical system.

  As a zoom lens that satisfies these requirements, there is known a four-group zoom lens including first to fourth lens units having positive, negative, positive, and positive refractive powers in order from the object side to the image side.

  Among these, a so-called rear focus type four-group zoom lens is known that performs zooming by moving the second lens group, corrects image plane fluctuations accompanying zooming by the fourth lens group, and performs focusing. Yes.

  In this rear focus type four-group zoom lens, a lens unit having a negative refractive power is disposed on the object side and a lens group having a positive refractive power is disposed on the image side as a lens configuration of the first lens unit, and a wide angle of view. A zoom lens that achieves the above has been known (Patent Documents 1 and 2).

  In addition, as a zoom lens that satisfies the above-described requirements, a five-group zoom lens that includes first to fifth lens units having positive, negative, positive, positive, and positive refractive powers in order from the object side to the image side is known. Yes.

In this 5-group zoom lens, a zoom lens having a relatively wide field angle is known in which zooming is performed by moving the second lens group and the fourth lens group, and focusing is performed by moving the fourth lens group (Patent Document). 3, 4).
JP-A-11-287952 JP-A-11-287554 JP 09-090221 A JP 2002-365539 A

  When the rear focus method is used in the zoom lens, the entire lens system is reduced in size compared to the zoom lens that performs focusing with the first lens group, enabling quick focusing and facilitating close-up photography. It is done.

  On the other hand, however, aberration fluctuations during focusing increase.

  In addition, if it is intended to increase the angle of view and the zoom ratio, it becomes difficult to obtain high optical performance over the entire zoom range.

  Therefore, in a rear focus type zoom lens, in order to obtain a high optical performance in the entire zoom range while achieving a wide angle of view and a high zoom ratio, the lens configuration of each lens group, particularly the lens configuration of the first lens group Must be set appropriately.

  Furthermore, in order to obtain a back focus that is long enough to arrange the color separation optical system on the image side, it is necessary to appropriately set the refractive power arrangement and the lens configuration of each lens group.

  In particular, in the zoom type 4-group zoom lens and 5-group zoom lens described above, if the lens configuration of the first lens group is not set appropriately, the entire screen and the entire zoom range can be obtained when a wide angle of view and a high zoom ratio are achieved. It becomes very difficult to obtain good optical performance over a long period of time.

  An object of the present invention is to provide a zoom lens that has a wide angle of view, a high zoom ratio, and high optical performance over the entire zoom range, and an image pickup apparatus having the zoom lens.

The zoom lens of the present invention is
In order from the object side to the image side, there is a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens group having a positive refractive power. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, and the most image side. The absolute value of refractive power is stronger on the object side than on the image side, and the object side consists of a convex positive lens.
In the first lens group, the composite focal length of one or more negative lenses having a concave surface on the image side, a concave lens on the object side, and one or more positive lenses having a biconvex shape is defined as f1FF, and the focal length of the first lens group is defined as f1. and when,
0.02 <f1 / f1FF <0.78 (1)
It is characterized by satisfying the following conditions.

In order from the object side to the image side, there is a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens group having a positive refractive power. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, a biconvex positive lens, a cemented lens of a negative lens having a concave surface and a positive lens on the image side, or a negative lens having a concave surface on the image side, Consists of two positive positive lenses,
When the composite focal length of the negative lens having the concave surface on the image side, the concave lens on the object side, and the positive lens having the biconvex shape is f1FF, and the focal length of the first lens group is f1 in the first lens group,
0.02 <f1 / f1FF <0.78 (1)
It is characterized by satisfying the following conditions.

In order from the object side to the image side, there is a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens group having a positive refractive power. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, The absolute value is larger on the object side than on the image side, and the object side consists of one or more positive lenses having a convex surface.
The composite focal length of one or more negative lenses having a concave surface on the image side, a concave lens on the object side, and one or more positive lenses having a biconvex shape in the first lens group is f1FF, and the focal length of the first lens group is f1. And when
0.02 <f1 / f1FF <0.78
It is characterized by satisfying the following conditions.

In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, A zoom lens having a fifth lens unit having a refractive power of 5 mm, and wherein the second and fourth lens units move during zooming,
The first lens group includes a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, a biconvex positive lens, a cemented lens of a negative lens having a concave surface and a positive lens on the image side, or a negative lens having a concave surface on the image side, and Consists of two positive positive lenses,
When the composite focal length of the negative lens having the concave surface on the image side, the concave lens on the object side, and the biconvex positive lens in the first lens group is f1FF, and the focal length of the first lens group is f1.
0.02 <f1 / f1FF <0.78 (1)
It is characterized by satisfying the following conditions.

  According to the present invention, as described above, by specifying the lens configuration, it is possible to obtain a zoom lens that achieves high optical performance over the entire zoom region with a wide angle of view and a high zoom ratio.

  Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below.

  1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention, and FIGS. 2, 3, and 4 are the wide-angle end and intermediate zoom position of the zoom lens according to Embodiment 1, respectively. FIG. 6 is an aberration diagram at the telephoto end (long focal length end).

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention, and FIGS. 6, 7, and 8 are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. It is.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 10, 11, and 12 are aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 3, respectively. It is.

  FIG. 13 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 4 of the present invention. FIGS. 14, 15, and 16 are aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 4, respectively. It is.

  FIG. 17 is a schematic diagram of a main part of a video camera (imaging device) including the zoom lens of the present invention.

  The zoom lens of each embodiment is a photographic lens system used in an imaging apparatus. In the lens cross-sectional view, ZL is a zoom lens, and CB is a camera body.

  L1 is a first lens group having a positive refractive power (optical power = reciprocal of focal length), L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is positive. A fourth lens unit having a refractive power, L5 is a fifth lens unit having a positive refractive power. SP is an aperture stop for adjusting the amount of light, and is located on the object side of the third lens unit L3.

  In Example 4 of FIG. 13, GA is a protective glass provided as needed for the purpose of protecting the zoom lens ZL. In addition, you may use protective glass GA similarly in Examples 1-3.

  GB is an optical block corresponding to a color separation prism, an optical filter, a face plate, a low-pass filter, and the like. IP is an image plane, and when used as a photographing optical system for a video camera or a digital still camera, when the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is a silver salt film camera Corresponds to the film surface.

  Each element from the first lens group L1 to the fifth lens group L5 (protective glass GA in Example 4 of FIG. 13) constitutes an element of the zoom lens (zoom lens unit) ZL. The glass block GB and the image sensor are housed in the camera body CB. The zoom lens unit ZL is detachably attached to the camera body CB via the mount member C.

  In the aberration diagrams, d and g are d-line and g-line, respectively, ΔM and ΔS are meridional image plane, sagittal image plane, and lateral chromatic aberration are represented by g-line.

  Fno is the F number, and ω is the half angle of view of the shooting angle of view.

  In each of the following embodiments, the zoom at the wide-angle end and the telephoto end when the lens unit for zooming (in each embodiment, the second lens unit L2) is positioned at both ends of the movable range on the optical axis on the mechanism. Says the position.

  In each embodiment, zooming (zooming) from the wide-angle end to the telephoto end is performed by moving the second lens unit L2 toward the image side as indicated by an arrow, and the image plane variation caused by the zooming is changed. The four lens unit L4 is moved and corrected so as to have a convex locus on the object side.

  Further, a rear focus type is employed in which focusing is performed by moving a part or all of the fourth lens unit L4 (which is all in each embodiment) on the optical axis.

  The movement trajectory accompanying zooming of the fourth lens group varies depending on the object distance.

  A solid curve 4a and a dotted curve 4b relating to the fourth lens unit L4 are movement trajectories for correcting image plane fluctuations accompanying zooming when focusing on an object at infinity and an object at close distance, respectively. Thus, by making the fourth lens unit L4 a locus convex toward the object side, the space between the third lens unit L3 and the fourth lens unit L4 can be effectively used, and the entire lens length can be shortened effectively. Has been achieved.

  In each embodiment, for example, when focusing from an infinitely distant object to a close object at the telephoto end, the fourth lens unit L4 is moved forward as indicated by an arrow 4c. The first lens unit L1 and the third lens unit L3 are fixed in the optical axis direction for zooming and focusing, but may be moved as necessary for aberration correction.

  In each embodiment, image blur when the entire optical system vibrates by moving a part or all of the third lens group (anti-vibration lens group) so as to have a component perpendicular to the optical axis. I am trying to correct it. That is, vibration isolation is performed.

  As a result, image stabilization is performed without newly adding an optical member such as a variable apex angle prism or a lens group for image stabilization, thereby preventing the entire optical system from becoming large.

  The video camera (imaging device) of the present invention shown in FIG. 17 has at least the zoom lens, a color separation element, an imaging element corresponding to each color divided by the color separation element, an imaging signal processing circuit, and the like. Yes.

  First, the lens configuration of each lens group of Examples 1 to 3 in FIGS. 1, 5, and 9 will be described.

  In Examples 1 to 3, in order from the object side to the image side, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, the third lens unit L3 having a positive refractive power, and a positive lens unit. The lens unit includes a fourth lens unit L4 having a refractive power and a fifth lens unit L5 having a positive refractive power.

  During zooming, the second and fourth lens units L2 and L4 move as described above.

  The first lens unit L1 includes a negative lens having a concave surface on the image side, a lens having a concave surface on the object side (refractive power may be positive or negative), a positive lens having a biconvex shape, and a negative lens having a concave surface on the image side. A cemented lens with the lens (Examples 1 and 3) or a negative lens (Example 2) having a concave surface on the image side, and two positive lenses having a convex surface on the object side. Note that the order of these is not necessarily the order from the object side.

  Further, the first lens unit L1 includes, from the object side, one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens including a negative lens and a positive lens, or a negative lens. The absolute value of the lens and refractive power may be larger on the object side than on the image side, and the object side may be a convex positive lens. Note that the order of these is not necessarily the order from the object side.

  Here, when the constituent elements as described above are arranged in order from the object side, a negative lens-positive lens cemented lens or a negative lens in the first lens unit L1 and a positive lens closest to the image plane side are provided. The axial chromatic aberration and spherical aberration at the telephoto end are corrected well.

  The first lens group includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, and a refractive power. One or more positive lenses having an absolute value larger on the object side than the image side and convex on the object side may be used. That is, the order of arrangement is not necessarily the order from the object side. However, as described above, in order to satisfactorily correct axial chromatic aberration and spherical aberration, it is desirable to provide a cemented lens or a negative lens and a positive lens closest to the image plane in the first lens group.

  In addition, by configuring the first lens unit L1 as described above, the distortion aberration can be reduced to a normal angle of view in spite of a zoom lens having an ultra wide angle of view of 75 degrees or more at the wide angle end. The aberration is corrected to the same level as the lens.

  Furthermore, astigmatism and curvature of field are corrected well.

  The second lens unit L2 includes, in order from the object side to the image side, a negative meniscus lens having a concave surface on the image side, a cemented lens of a positive lens having a convex surface on the image side and a biconcave negative lens, and a biconvex positive lens and a negative lens. It consists of a cemented lens with a lens or a single positive lens.

  By configuring the second lens unit L2 having a zooming function in this way, aberration correction is performed satisfactorily. In addition, the lens configuration of the second lens unit L2 favorably corrects aberration variations due to zooming in order to obtain high-performance optical performance.

  In each embodiment, an aspherical surface is introduced into the second lens unit L2. As a result, astigmatism at the wide-angle end is corrected well, and high optical performance is obtained.

  The third lens unit L3 includes, in order from the object side to the image side, a cemented lens of a biconcave negative lens and a positive lens, a cemented lens of a positive lens and a negative lens, or a positive lens.

  The third lens unit L3 has at least one aspheric surface. As a result, spherical aberration, coma and axial chromatic aberration at the wide-angle end are corrected well.

  When an aspheric surface is introduced into the third lens unit L3 at this time, it is desirable that the aspheric shape be such that the positive refractive power becomes weaker toward the periphery of the lens.

  A part or all of the third lens unit L3 moves so as to have a component perpendicular to the optical axis to displace the image. That is, vibration isolation is performed.

  The fourth lens unit L4 includes a positive lens and a cemented lens of a negative lens and a positive lens in order from the object side to the image side.

  The fifth lens unit L5 includes, in order from the object side to the image side, a cemented lens of a biconvex positive lens and a negative lens.

  The lens configuration of the fifth lens unit L5 affects the fourth lens unit as a whole. The fifth lens unit L5 bears part of correction of spherical aberration and chromatic aberration performed by the fourth lens unit L4. As a result, the number of lenses constituting the fourth lens unit L4, which is a moving lens unit, is reduced. Further, the fourth lens unit L4 has an optimum configuration for performing instantaneous focusing.

  The fifth lens unit L5 corrects aberrations that cannot be corrected by the first lens unit L1 to the fourth lens unit L4, particularly spherical aberration and chromatic aberration, and realizes aberration correction suitable for high image quality. .

  Next, the lens configuration of each lens group of Example 4 in FIG. 13 will be described.

  In Example 4, in order from the object side to the image side, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, the third lens unit L3 having a positive refractive power, and a positive refractive power. The fourth lens unit L4.

  During zooming, the second and fourth lens units L2 and L4 move as described above.

  The first lens unit L1 includes a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, a biconvex positive lens, a cemented lens of a negative lens having a concave surface on the image side and a positive lens, and two positive lenses having a convex surface on the object side. It is made up.

  The first lens unit L1 includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, and the most image side. In addition, the absolute value of the refractive power may be stronger on the object side than on the image side, and the object side may be composed of a convex positive lens.

  The lens configurations of the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 and the effects obtained therefrom are the same as those in Examples 1 to 3.

In each embodiment, the image side in the first lens unit L1 has one or more negative lenses having a concave surface, the object side has a concave lens, the combined focal length of one or more biconvex positive lenses or the image side has a concave negative lens, the object When the combined focal length of the concave lens on the side, the biconvex positive lens is f1FF, and the focal length of the first lens unit L1 is f1,
0.02 <f1 / f1FF <0.78 (1)
Is satisfied.

  In general, a wide converter lens that is inserted into and removed from the object side of the first lens unit is composed of an afocal system having a refractive power of approximately zero.

  In each embodiment, assuming that a part of the first lens unit L1 is an afocal system, the lens configuration corresponds to a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, and a positive lens having a biconvex shape. To do.

  However, in each of the embodiments, since no fall system is added, a composite system including a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, and a positive lens having a biconvex shape has a predetermined refractive power.

  Conditional expression (1) appropriately sets the refractive power (reciprocal of the focal length) of the synthesis system at this time.

  Conditional expression (1) is a condition for reducing the size of the entire lens system. If the combined focal length f1FF becomes longer than the lower limit of conditional expression (1), the entire lens system becomes larger. Conversely, if the upper limit is exceeded, it becomes difficult to correct spherical aberration.

  More preferably, the numerical range of conditional expression (1) should be set as follows.

0.2 <f1 / f1FF <0.7 (1a)
More preferably, the following should be satisfied.

0.3 <f1 / f1FF <0.65 (1b)
In each embodiment, at least one of the following conditions is satisfied, thereby obtaining an effect corresponding to each condition.

  Let the focal length of the second lens unit L2 be f2.

  The distance between the principal points of the first lens unit L1 and the second lens unit L2 at the wide-angle end is H12w. The focal length of the entire system at the wide angle end is fw.

  The curvature radii of the object side and the image side of the lens having a concave surface on the object side in the first lens unit L1 are RNF and RNR, respectively.

The F number of the entire system at the wide-angle end is F _no w. The air equivalent amount of the distance from the most image side lens surface at the wide angle end (from the final lens surface of the fifth lens group in Examples 1 to 3 and the final lens surface of the fourth lens group in Example 4) to the image surface. (Length when there is no optical block such as a prism) is defined as BF.

At this time,
-8.0 <H12w / fw <-3.2 (2)
0.8 <RNF / RNR <1.4 (3)
2.5 <| f2 / fw | <4.1 (4)

One or more of the following conditions are satisfied.

  Next, the technical meaning of each conditional expression described above will be described.

  Conditional expression (2) is a condition for shortening the overall length of the lens while favorably correcting various aberrations. If the distance between the principal points exceeds the upper limit of conditional expression (2), the diameter of the front lens increases and it becomes difficult to reduce the size.

  Conversely, when the principal point interval is reduced beyond the lower limit of conditional expression (2), it becomes difficult to correct astigmatism and lateral chromatic aberration at the intermediate zoom position from the wide-angle end.

  Conditional expression (3) is a condition for satisfactorily correcting various aberrations occurring at the wide-angle end, and in particular, a condition for satisfactorily correcting distortion and lateral chromatic aberration. If the curvature exceeds the upper limit of conditional expression (3), the lateral chromatic aberration increases in the positive direction, which is not preferable. On the contrary, when the lower limit of conditional expression (3) is exceeded, distortion is greatly generated in the minus direction, which is not preferable.

  Conditional expressions (4) and (5) are conditions for miniaturizing the entire lens system, widening the angle of view, and ensuring a long back focus. A balanced lens system can be achieved by satisfying at least one of conditional expressions (4) and (5).

  Conditional expression (4) specifies the refractive power of the zooming unit for achieving a wide angle of view with respect to the negative refractive power of the second lens unit L2.

  Conditional expression (4) is for ensuring a high zoom ratio while reducing aberration fluctuations associated with zooming.

  When the upper limit of conditional expression (4) is exceeded and the negative refractive power of the second lens unit L2 becomes weak, it is difficult to sufficiently increase the afocal magnification in the zooming unit, and it is difficult to secure a desired back focus length. Become.

  Further, the amount of movement of the second lens unit L2 for obtaining a desired zoom ratio increases, and the distance between the aperture stop SP and the first lens unit L1 increases, leading to an increase in the front lens diameter.

  Conversely, if the negative refractive power of the second lens unit L2 exceeds the lower limit of the conditional expression (4), the Petzval sum increases in the negative direction, the field curvature increases, and aberrations associated with zooming occur. Fluctuation increases.

  Conditional expression (5) is a relational expression between the back focus BF and the F number of the zoom lens. Conditional expression (5) is for obtaining a high-quality image by spectrally separating the three color lights using a color separation prism employed in a high-performance camera and capturing each image with an image sensor. .

  If the F number is increased beyond the upper limit of conditional expression (5), high-order spherical aberration and coma aberration are often generated, and correction of these aberrations becomes difficult. On the other hand, if the lower limit of conditional expression (5) is exceeded and the F-number becomes dark, the axial ray bundle becomes thin, and the color separation prism arranged on the image side of the zoom lens becomes smaller. As a result, the back focus becomes unnecessarily long, which leads to an increase in the total length of the lens system, which is not preferable.

In each embodiment, the third lens unit L3 includes a plurality of lenses with at least one air interval. The length of at least one air interval in the optical axis direction is D3a, and the focal length of the third lens group is f3. At this time, 0.01 <D3a / f3 <0.08 (6)
Is satisfied.

  The air gap in the third lens unit L3 is for inserting / removing a light amount adjusting filter such as a single or a plurality of ND filters in the optical path separately from the light amount adjusting diaphragm.

  In each embodiment, the amount of light incident on the image sensor is adjusted by inserting or removing a single or a plurality of light amount adjustment filters into the optical path.

  If the distance exceeds the upper limit of conditional expression (6) and the distance becomes too wide, the entire lens system becomes large, and at the same time, it becomes difficult to correct spherical aberration at the wide-angle end. On the other hand, when the lower limit is exceeded, it becomes difficult to insert the light amount adjustment filter into the optical path.

In Examples 1 to 3, the focal lengths of the third lens unit L3 and the fifth lens unit L5 are set to f3 and f5, respectively. At this time, 1.3 <f3 / f5 <3.1 (7)
Is satisfied.

  Conditional expression (7) relates to the ratio of the focal lengths of the third lens unit L3 and the fifth lens unit L5, and is a condition for increasing the zoom ratio and ensuring a long back focus. If the upper limit of conditional expression (7) is exceeded and the focal length of the third lens unit L3 increases, the divergence of the light beam emitted from the third lens unit L3 increases, and the back focus increases, but the fourth lens unit L4 is effective. The diameter increases and the entire lens system becomes heavier.

  Conversely, if the focal length of the third lens unit L3 becomes shorter than the lower limit of conditional expression (7), it will be difficult to ensure a sufficiently long back focus. Further, when the focal length of the fifth lens unit L5 is increased, the correction of spherical aberration becomes insufficient.

  It is more preferable to set the numerical ranges of the conditional expressions (2) to (7) as follows because it is easy to maintain good optical performance.

-7.0 <H12w / fw <-3.4 (2a)
0.9 <RNF / RNR <1.3 (3a)
2.7 <| f2 / fw | <3.8 (4a)

0.015 <D3a / f3 <0.06 (6a)
1.5 <f3 / f5 <2.6 (7a)
In each embodiment, each element is specified such that distortion aberration when focusing on an object at infinity at the wide-angle end is -8% to 0% over the entire screen.

  As the angle of view increases, the distortion increases more and more negative distortion, that is, barrel distortion occurs.

  In recent years, the image display surface has become a flat TV, and barrel distortion has become conspicuous. Therefore, it is necessary to correct distortion well.

  Conventionally, in order to correct distortion, a positive lens is disposed closest to the object side or an aspherical surface is disposed for correction.

  In each embodiment, the first lens unit L1 is configured as described above to correct distortion well.

  In Examples 1 to 3, an optical member having a small refractive power is provided on the image side of the fifth lens unit L5, in Example 4 on the image side of the fourth lens unit L4, and on the object side of the first lens unit L1. It may be arranged.

  Next, an embodiment of a video camera (imaging device) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 17, reference numeral 10 denotes a video camera body or digital still camera body, and 11 denotes a photographing optical system constituted by the zoom lens of the present invention. Reference numeral 12 denotes one of image sensors such as a CCD that receives a subject image by the photographing optical system 11, and 13 denotes a recording unit that records the subject image received by the image sensor 12. Reference numeral 14 denotes a finder for observing the subject image displayed on the display element.

  The display element is constituted by a liquid crystal panel or the like, and a live image formed on the image sensor 12 is displayed. Reference numeral 15 denotes a liquid crystal display panel having a function equivalent to that of the finder (not shown).

  Thus, by applying the zoom lens of the present invention to an imaging apparatus such as a video camera, an optical apparatus having high optical performance is realized.

  As described above, according to each embodiment, the entire lens system can be miniaturized, and a zoom lens having high optical performance despite a high zoom ratio and an imaging apparatus using the same can be achieved.

  In addition, according to each of the embodiments, the zoom ratio is 6 to 8 times, and the entire zooming range from the wide angle end to the telephoto end zoom position regardless of the high zooming ratio, and from an infinite object to an extremely close object. High optical performance can be obtained over the entire object distance.

  In addition, a long back focus in which an optical element such as a color separation prism enters can be obtained while the F-number is about 1.6 and a large aperture ratio. In addition, a zoom lens having good performance over the entire zoom range and the entire object distance can be obtained while ensuring a space for entering a complicated aperture mechanism and a space for entering an ND filter.

  The numerical examples 1 to 4 corresponding to the first to fourth examples are shown below. In each numerical example, i indicates the order of the surfaces from the object side, Ri is the radius of curvature of each surface, Di is the member thickness or air spacing between the i-th surface and the (i + 1) -th surface, Ni and νi are Refractive index and Abbe number for d line are shown respectively. In each numerical embodiment, the three surfaces closest to the image are planes corresponding to a crystal low-pass filter, an infrared cut filter, and the like.

  When the aspherical shape is X with respect to the displacement in the direction of the optical axis at the position of the height H from the optical axis,

It is represented by Where R is the paraxial radius of curvature, k is the conic constant, A, B, C.I. D and E are aspheric coefficients.

“E-X” means “× 10 ^−X ”. f represents a focal length, Fno represents an F number, and ω represents a half angle of view. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

Numerical example 1

f = 1 to 5.84 Fno = 1.68 to 2.65 2ω = 82.5 to 17.1

R 1 = -752.576 D 1 = 0.99 N 1 = 1.603112 ν 1 = 60.6
R 2 = 10.654 D 2 = 6.11
R 3 = -17.574 D 3 = 1.34 N 2 = 1.846660 ν 2 = 23.9
R 4 = -16.934 D 4 = 5.46
R 5 = 24.410 D 5 = 2.25 N 3 = 1.712995 ν 3 = 53.9
R 6 = -27.041 D 6 = 0.15
R 7 = 35.967 D 7 = 0.74 N 4 = 1.846660 ν 4 = 23.9
R 8 = 9.654 D 8 = 1.96 N 5 = 1.487490 ν 5 = 70.2
R 9 = 70.768 D 9 = 0.06
R10 = 24.197 D10 = 0.84 N 6 = 1.516330 ν 6 = 64.1
R11 = 156.617 D11 = 0.06
R12 = 9.104 D12 = 0.98 N 7 = 1.806098 ν 7 = 40.9
R13 = 20.646 D13 = Variable
R14 = 11.084 D14 = 0.29 N 8 = 1.882997 ν 8 = 40.8
R15 = 2.636 D15 = 1.02
R16 = -68.317 D16 = 1.49 N 9 = 1.805181 ν 9 = 25.4
R17 = -2.798 D17 = 0.29 N10 = 1.848620 ν10 = 40.0
R18 * = 5.554 D18 = 0.46
R19 = 5.750 D19 = 1.26 N11 = 1.603420 ν11 = 38.0
R20 = -3.153 D20 = 0.23 N12 = 1.882997 ν12 = 40.8
R21 = -9.077 D21 = variable
R22 = Aperture D22 = 1.17
R23 = -6.072 D23 = 0.26 N13 = 1.696797 ν13 = 55.5
R24 = 3.575 D24 = 1.14 N14 = 1.688931 ν14 = 31.1
R25 * = -13.784 D25 = 1.76
R26 = 21.400 D26 = 1.61 N15 = 1.581439 ν15 = 40.8
R27 = -4.097 D27 = 0.23 N16 = 2.003300 ν16 = 28.3
R28 = -7.310 D28 = variable
R29 = 51.299 D29 = 0.88 N17 = 1.583126 ν17 = 59.4
R30 * = -14.087 D30 = 0.06
R31 = 12.799 D31 = 0.26 N18 = 1.846660 ν18 = 23.9
R32 = 6.030 D32 = 1.48 N19 = 1.496999 ν19 = 81.5
R33 = -9.465 D33 = variable
R34 = 12.383 D34 = 0.70 N20 = 1.487490 ν20 = 70.2
R35 = -8.097 D35 = 0.20 N21 = 1.698947 ν21 = 30.1
R36 = -33.046 D36 = 1.46
R37 = ∞ D37 = 5.84 N22 = 1.589130 ν22 = 61.2
R38 = ∞ D38 = 1.10 N23 = 1.516330 ν23 = 64.2
R39 = ∞

* Aspherical aspherical coefficient
R18 k = -3.90735e-01 B = -2.47000e-03 C = -1.08204e-04 D = 0.00
E = 0.00 F = 0.00
R25 k = -1.14046e + 01 B = 1.43303e-05 C = -1.62497e-06 D = 1.20851e-06
E = 0.00 F = 0.00
R30 k = 2.73642 B = 2.51117e-04 C = 3.07675e-06 D = -5.87407e-07
E = 1.72443e-08 F = 0.00



\ Focal length 1.00 3.95 5.84
Variable interval \
D13 0.29 5.96 7.04
D21 7.60 1.93 0.85
D28 2.13 1.38 1.80
D33 1.46 2.21 1.79


Numerical example 2

f = 1 to 5.84 Fno = 1.68 to 2.65 2ω = 82.5 to 17.1

R 1 = 305.324 D 1 = 0.99 N 1 = 1.603112 ν 1 = 60.6
R 2 = 10.031 D 2 = 5.85
R 3 = -17.214 D 3 = 1.34 N 2 = 1.581439 ν 2 = 40.8
R 4 = -14.740 D 4 = 4.16
R 5 = 15.867 D 5 = 2.63 N 3 = 1.693495 ν 3 = 50.8
R 6 = -30.714 D 6 = 0.15
R 7 = 127.492 D 7 = 0.70 N 4 = 1.846660 ν 4 = 23.9
R 8 = 9.864 D 8 = 0.30
R 9 = 11.828 D 9 = 1.75 N 5 = 1.517417 ν 5 = 52.4
R10 = -111.042 D10 = 0.06
R11 = 10.549 D11 = 1.10 N 6 = 1.882997 ν 6 = 40.8
R12 = 35.921 D12 = variable
R13 = 11.785 D13 = 0.29 N 7 = 1.882997 ν 7 = 40.8
R14 = 2.562 D14 = 1.04
R15 = -85.374 D15 = 1.23 N 8 = 1.805181 ν 8 = 25.4
R16 = -2.788 D16 = 0.29 N 9 = 1.848620 ν 9 = 40.0
R17 * = 5.971 D17 = 0.39
R18 = 5.687 D18 = 1.23 N10 = 1.603420 ν10 = 38.0
R19 = -3.739 D19 = 0.23 N11 = 1.882997 ν11 = 40.8
R20 = -9.705 D20 = variable
R21 = Aperture D21 = 1.17
R22 = -5.601 D22 = 0.26 N12 = 1.677900 ν12 = 55.3
R23 = 3.560 D23 = 1.14 N13 = 1.688931 ν13 = 31.1
R24 * = -13.864 D24 = 1.75
R25 = 18.511 D25 = 1.61 N14 = 1.567322 ν14 = 42.8
R26 = -4.216 D26 = 0.23 N15 = 2.003300 ν15 = 28.3
R27 = -7.397 D27 = Variable
R28 = 68.339 D28 = 0.88 N16 = 1.583126 ν16 = 59.4
R29 * = -13.030 D29 = 0.06
R30 = 11.083 D30 = 0.26 N17 = 1.846660 ν17 = 23.9
R31 = 5.550 D31 = 1.45 N18 = 1.496999 ν18 = 81.5
R32 = -10.111 D32 = variable
R33 = 16.663 D33 = 0.70 N19 = 1.487490 ν19 = 70.2
R34 = -8.481 D34 = 0.20 N20 = 1.698947 ν20 = 30.1
R35 = -30.035 D35 = 1.46
R36 = ∞ D36 = 5.84 N21 = 1.589130 ν21 = 61.2
R37 = ∞ D37 = 1.10 N22 = 1.516330 ν22 = 64.2
R38 = ∞


* Aspherical aspherical coefficient
R17 k = -4.45518e-01 B = -2.21385e-03 C = -1.46718e-04 D = 0.00
E = 0.00 F = 0.00
R24 k = -5.98345 B = 4.19262e-04 C = -1.99511e-07 D = 1.53944e-07
E = 0.00 F = 0.00
R29 k = 1.43684 B = 2.42859e-04 C = 2.74441e-06 D = -7.00580e-07
E = 3.08679e-08 F = 0.00



\ Focal length 1.00 3.96 5.84
Variable interval \
D12 0.29 6.77 8.00
D20 8.58 2.10 0.87
D27 2.12 1.17 1.34
D32 1.46 2.41 2.24



Numerical example 3

f = 1 to 7.47 Fno = 1.68 to 2.85 2ω = 82.5 to 13.4

R 1 = -1283.218 D 1 = 0.99 N 1 = 1.603112 ν 1 = 60.6
R 2 = 10.756 D 2 = 6.16
R 3 = -17.733 D 3 = 1.34 N 2 = 1.846660 ν 2 = 23.9
R 4 = -16.973 D 4 = 5.48
R 5 = 25.632 D 5 = 2.25 N 3 = 1.712995 ν 3 = 53.9
R 6 = -26.065 D 6 = 0.15
R 7 = 39.658 D 7 = 0.74 N 4 = 1.846660 ν 4 = 23.9
R 8 = 9.968 D 8 = 1.96 N 5 = 1.487490 ν 5 = 70.2
R 9 = 101.722 D 9 = 0.06
R10 = 22.510 D10 = 0.88 N 6 = 1.516330 ν 6 = 64.1
R11 = 73.425 D11 = 0.06
R12 = 9.257 D12 = 0.98 N 7 = 1.806098 ν 7 = 40.9
R13 = 20.842 D13 = Variable
R14 = 12.558 D14 = 0.29 N 8 = 1.882997 ν 8 = 40.8
R15 = 2.661 D15 = 0.99
R16 = -166.292 D16 = 1.49 N 9 = 1.805181 ν 9 = 25.4
R17 = -2.792 D17 = 0.29 N10 = 1.848620 ν10 = 40.0
R18 * = 5.254 D18 = 0.44
R19 = 5.550 D19 = 1.26 N11 = 1.603420 ν11 = 38.0
R20 = -3.055 D20 = 0.23 N12 = 1.882997 ν12 = 40.8
R21 = -8.551 D21 = variable
R22 = Aperture D22 = 1.17
R23 = -6.232 D23 = 0.26 N13 = 1.696797 ν13 = 55.5
R24 = 3.709 D24 = 1.14 N14 = 1.688931 ν14 = 31.1
R25 * = -14.957 D25 = 1.67
R26 = 20.929 D26 = 1.61 N15 = 1.581439 ν15 = 40.8
R27 = -4.101 D27 = 0.23 N16 = 2.003300 ν16 = 28.3
R28 = -7.239 D28 = variable
R29 = 47.690 D29 = 0.88 N17 = 1.583126 ν17 = 59.4
R30 * = -13.707 D30 = 0.06
R31 = 12.761 D31 = 0.26 N18 = 1.846660 ν18 = 23.9
R32 = 5.986 D32 = 1.51 N19 = 1.496999 ν19 = 81.5
R33 = -9.611 D33 = variable
R34 = 13.277 D34 = 0.70 N20 = 1.487490 ν20 = 70.2
R35 = -8.604 D35 = 0.20 N21 = 1.698947 ν21 = 30.1
R36 = -39.874 D36 = 1.46
R37 = ∞ D37 = 5.84 N22 = 1.589130 ν22 = 61.2
R38 = ∞ D38 = 1.10 N23 = 1.516330 ν23 = 64.2
R39 = ∞


* Aspherical aspherical coefficient
R18 k = -6.63924e-01 B = -2.44889e-03 C = -1.23438e-04 D = 0.00
E = 0.00 F = 0.00
R25 k = -1.13530e + 01 B = 1.52934e-04 C = 2.28654e-06 D = -1.40095e-07
E = 0.00 F = 0.00
R30 k = 2.97547e + 00 B = 2.84769e-04 C = 3.41041e-06 D = -6.06424e-07
E = 2.48786e-08 F = 0.00


\ Focal length 1.00 4.68 7.47
Variable interval \
D13 0.29 6.65 7.87
D21 8.07 1.70 0.49
D28 2.12 1.41 2.17
D33 1.54 2.26 1.50



Numerical example 4

f = 1 to 7.27 Fno = 1.68 to 2.85 2ω = 82.5 to 13.8

R 1 = 140.342 D 1 = 0.99 N 1 = 1.603112 ν 1 = 60.6
R 2 = 10.377 D 2 = 6.77
R 3 = -18.307 D 3 = 1.34 N 2 = 1.846660 ν 2 = 23.9
R 4 = -18.744 D 4 = 6.08
R 5 = 33.008 D 5 = 2.25 N 3 = 1.712995 ν 3 = 53.9
R 6 = -24.336 D 6 = 0.15
R 7 = 54.160 D 7 = 0.74 N 4 = 1.846660 ν 4 = 23.9
R 8 = 12.226 D 8 = 1.96 N 5 = 1.487490 ν 5 = 70.2
R 9 = -92.832 D 9 = 0.06
R10 = 26.605 D10 = 0.80 N 6 = 1.516330 ν 6 = 64.1
R11 = 98.896 D11 = 0.06
R12 = 9.489 D12 = 0.89 N 7 = 1.806098 ν 7 = 40.9
R13 = 16.887 D13 = variable
R14 = 8.895 D14 = 0.29 N 8 = 1.882997 ν 8 = 40.8
R15 = 2.792 D15 = 1.08
R16 = -104.592 D16 = 1.49 N 9 = 1.805181 ν 9 = 25.4
R17 = -2.693 D17 = 0.29 N10 = 1.848620 ν10 = 40.0
R18 * = 5.697 D18 = 0.50
R19 = 5.667 D19 = 1.46 N11 = 1.603420 ν11 = 38.0
R20 = -3.180 D20 = 0.23 N12 = 1.882997 ν12 = 40.8
R21 = -11.328 D21 = variable
R22 = Aperture D22 = 1.17
R23 = -6.656 D23 = 0.26 N13 = 1.696797 ν13 = 55.5
R24 = 4.637 D24 = 1.14 N14 = 1.688931 ν14 = 31.1
R25 * = -15.371 D25 = 2.41
R26 = 33.101 D26 = 1.69 N15 = 1.567322 ν15 = 42.8
R27 = -4.447 D27 = 0.23 N16 = 2.003300 ν16 = 28.3
R28 = -7.148 D28 = variable
R29 = 17.519 D29 = 0.96 N17 = 1.516330 ν17 = 64.1
R30 * = -13.273 D30 = 0.06
R31 = 8.770 D31 = 0.26 N18 = 1.922860 ν18 = 18.9
R32 = 5.632 D32 = 1.50 N19 = 1.433870 ν19 = 95.1
R33 = -11.683 D33 = variable
R34 = ∞ D34 = 0.70 N20 = 1.487490 ν20 = 70.2
R35 = ∞ D35 = 0.20 N21 = 1.698947 ν21 = 30.1
R36 = ∞ D36 = 1.61
R37 = ∞ D37 = 5.84 N22 = 1.589130 ν22 = 61.2
R38 = ∞ D38 = 1.10 N23 = 1.516330 ν23 = 64.2
R39 = ∞


* Aspherical aspherical coefficient
R18 k = 3.06503e-02 B = -2.34534e-03 C = -1.05213e-04 D = 0.00
E = 0.00 F = 0.00
R25 k = -7.56262e + 00 B = 2.46057e-04 C = -1.35044e-06 D = -1.57075e-06
E = 0.00 F = 0.00
R30 k = 1.13937e + 00 B = 3.77437e-04 C = 4.70922e-06 D = -7.23878e-07
E = 2.90257e-08 F = 0.00



\ Focal length 1.00 4.49 7.27
Variable interval \
D13 0.29 7.14 8.45
D21 8.71 1.86 0.55
D28 2.98 2.44 2.83
D33 1.45 1.99 1.60

Lens sectional view of Example 1 Aberration diagram at the wide-angle end of the numerical example corresponding to Example 1. Aberration diagram at the intermediate zoom position in the numerical value example corresponding to Example 1. Aberration diagram at the telephoto end of a numerical example corresponding to Example 1. Lens sectional view of Example 2 Aberration diagram at the wide-angle end of a numerical example corresponding to Example 2. Aberration diagram at the intermediate zoom position of the numerical example corresponding to Example 2 Aberration diagram at the telephoto end of a numerical example corresponding to Example 2. Lens sectional view of Example 3 Aberration diagram at the wide-angle end of the numerical value example corresponding to Example 3 Aberration diagram at the intermediate zoom position in the numerical value example corresponding to Example 3 Aberration diagram at the telephoto end of a corresponding numerical example corresponding to Example 3. Lens sectional view of Example 4 Aberration diagrams at the wide-angle end of the numerical value example corresponding to Example 4. Aberration diagram at the intermediate zoom position in the numerical value example corresponding to Example 4 Aberration diagram at the telephoto end of a numerical example corresponding to Example 4. Schematic diagram of main parts of an imaging apparatus of the present invention

Explanation of symbols

ZL Zoom lens CB Camera body GA Protective glass GB Optical block C Mount member L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group SP Aperture IP Image surface G Glass block d d line g g line ΔS Sagittal image plane ΔM Meridional image plane Fno F number 10 Camera body 11 Imaging optical system 12 Imaging element 13 Recording means 14 Viewfinder 15 Liquid crystal display panel

Claims (15)

In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are provided. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, and the most image side. The absolute value of refractive power is larger on the object side than on the image side, and the object side consists of a positive lens with a convex surface,
In the first lens group, the composite focal length of one or more negative lenses having a concave surface on the image side, a concave lens on the object side, and one or more positive lenses having a biconvex shape is defined as f1FF, and the focal length of the first lens group is defined as f1. and when,
0.02 <f1 / f1FF <0.78
A zoom lens characterized by satisfying the following conditions: In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are provided. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes a negative lens having a concave surface on the image side, a lens having a concave surface on the object side, a biconvex positive lens, a cemented lens of a negative lens having a concave surface and a positive lens on the image side, or a negative lens having a concave surface on the image side, Consists of two positive positive lenses,
When the composite focal length of the negative lens having the concave surface on the image side, the concave lens on the object side, and the positive lens having the biconvex shape is f1FF, and the focal length of the first lens group is f1 in the first lens group,
0.02 <f1 / f1FF <0.78
A zoom lens characterized by satisfying the following conditions: In order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are provided. A zoom lens in which the second and fourth lens groups move during zooming,
The first lens group includes one or more negative lenses having a concave surface on the image side, a lens having a concave surface on the object side, one or more positive lenses having a biconvex shape, a cemented lens or a negative lens composed of a negative lens and a positive lens, The absolute value is larger on the object side than on the image side, and the object side consists of one or more positive lenses having a convex surface.
The composite focal length of one or more negative lenses having a concave surface on the image side, a concave lens on the object side, and one or more positive lenses having a biconvex shape in the first lens group is f1FF, and the focal length of the first lens group is f1. And when
0.02 <f1 / f1FF <0.78
A zoom lens characterized by satisfying the following conditions:   4. The zoom lens according to claim 1, further comprising a fifth lens unit having a positive refractive power and disposed on the image side of the fourth lens unit. 5. When the distance between the principal points of the first lens group and the second lens group at the wide angle end is H12w, and the focal length of the entire system at the wide angle end is fw,
-8.0 <H12w / fw <-3.2
The zoom lens according to claim 1, wherein the following condition is satisfied. When the radius of curvature of the object side and the image side of the lens having a concave surface on the object side in the first lens group is RNF and RNR,
0.8 <RNF / RNR <1.4
The zoom lens according to claim 1, wherein the following condition is satisfied. The focal length of the second lens group is f2, the focal length of the entire system at the wide angle end is fw, the F number of the entire system at the wide angle end is F _no w, and the distance from the lens surface closest to the image side to the image plane at the wide angle end. When the air equivalent amount is BF,
2.5 <| f2 / fw | <4.1

The zoom lens according to claim 1, wherein the following condition is satisfied.   The second lens group includes, in order from the object side to the image side, a negative meniscus lens having a concave surface on the image side, a cemented lens of a positive lens having a convex surface and a biconcave negative lens on the image side, and a biconvex positive lens. The zoom lens according to claim 1, comprising a cemented lens with a negative lens or a single positive lens.   The third lens group includes, in order from the object side to the image side, a cemented lens of a biconcave negative lens and a positive lens, a cemented lens of a positive lens and a negative lens, or a single positive lens. The zoom lens according to any one of claims 1 to 8.   10. The zoom lens according to claim 1, wherein a part or all of the third lens group moves so as to have a component perpendicular to the optical axis to displace the image. . When the third lens group has a plurality of lenses with at least one air gap, the length of the at least one air gap in the optical axis direction is D3a, and the focal length of the third lens group is f3. ,
0.01 <D3a / f3 <0.08
The zoom lens according to claim 1, wherein the following condition is satisfied.   5. The zoom lens according to claim 3, wherein the fifth lens group includes a cemented lens of a biconvex positive lens and a negative lens in order from the object side to the image side. When the focal lengths of the third lens group and the fifth lens group are f3 and f5, respectively.
1.3 <f3 / f5 <3.1
The zoom lens according to claim 3, 4 or 12, wherein the following condition is satisfied.   The zoom lens according to claim 1, wherein an image is formed on a solid-state image sensor.   15. A photographing apparatus comprising: the zoom lens according to claim 1; and a solid-state image sensor that receives an image formed by the zoom lens.