JP2001305426A - Zoom lens and image pickup unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized portable zoom lens capable of covering an extremely wide variable power area by switching a wide angle state, a standard state and a telephoto state by a focal distance extent changeover switch, etc., besides, which can be manufactured at a low cost, and to provide an image pickup device using the zoom lens. SOLUTION: The zoom lens is constituted of a master lens system, a 5th lens group and a 6th lens group, the master lens system is constituted of a 1st lens group, a 2nd lens group, a 3rd lens group and a 4th lens group, the 5th lens group whose refractive power is negative is functioned as an auxiliary lens, is made to retreat outside the optical path in the standard state, and is inserted on the image side of the 4th lens group when in use so as to shift the focal distance extent of the master lens system to the telephoto side and so as to make the telephoto state, and the 6th lens group whose refractive power is negative as an auxiliary lens, is made to retreat outside the optical path in the standard state, and is inserted on the object side of the 1st lens group at the wide angle end in the standard state when in use so as to shift to a wide angle state shorter than the wide angle end in the standard state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens which realizes a lens system having a high zoom ratio mainly used for a consumer video camera by combining a main lens system, a wide-angle auxiliary lens and a telephoto auxiliary lens. The present invention relates to an imaging device using the zoom lens.

[0002]

2. Description of the Related Art In a conventional imaging apparatus, for example, a zoom lens used in a consumer video camera, a wide-angle conversion lens having an afocal system and an angular magnification of less than 1 is provided on the object side as means for changing a focal length range. In general, a telephoto conversion lens having an angular magnification of greater than 1 is mounted. With this method, the F-number of the zoom lens does not change.

Further, a lens system having a negative refractive power is mounted on the object side of the zoom lens, and an image of a subject viewed through the lens system having the negative refractive power is focused at a wide-angle end to form a wide-angle lens. There is also a method of changing, and there is a video camera incorporating the above lens system.

In a so-called single-lens reflex camera or video camera of an interchangeable lens type, a telephoto converter for mounting a negative lens system between an imaging lens and a camera body so as to convert the focal length of the imaging lens to the telephoto side. Some are called. With such a means, the F number of the entire lens system becomes darker by an amount multiplied by the magnification of the telephoto converter.

[0005] In a video camera for business use, a focus lens, a variable power lens,
By disposing the focus correction lens and the imaging lens in this order, and providing a long air gap in the imaging lens system, and inserting the lens system normally retracted out of the optical path into the air gap, the lens is removed from the camera body. A so-called built-in extender that converts the focal length to the telephoto side without detaching or changing the overall length is also used.

However, these conventional means for converting the focusable range of a zoom lens have the following problems.

That is, a detachable afocal conversion lens to be mounted on the object side of the zoom lens is large and heavy, and is inconvenient since a separate portable case or the like used when detached is required. When carrying both the telephoto conversion lens and the wide-angle conversion lens, the burden on the user is, for example, as much as carrying another video camera body.

The telephoto converter which is mounted between the imaging lens and the camera body can be made smaller than the afocal telephoto conversion lens. However, once the imaging lens is detached and mounted on the camera body. Since it is necessary to mount the imaging lens again, the detachability is inconvenient and the portability when detached is not as good as that of the afocal conversion lens.

The built-in extender, which is mainly used in professional video cameras, does not need to be attached and detached, so there is no particular problem in terms of portability. However, a configuration in which an extender optical system is incorporated in a fixed imaging lens group. Therefore, a space in which the extender optical system can be inserted is required in the imaging lens, and an increase in the size of the imaging lens, such as an increase in the overall length of the imaging lens, cannot be avoided. In general, in a consumer zoom lens, the position of the lens group closest to the object side is fixed, and correction and focusing at the time of zooming are performed by a lens group close to the image plane. None of them had both the zoom system and the function of the built-in extender.

[0010] Further, Japanese Patent Application Laid-Open No.
In Japanese Patent Publication No. 39, a zoom lens alone has a zoom ratio of 50.
Although a lens configuration capable of obtaining a magnification of 2.times. Is disclosed, in this zoom lens having a five-group configuration, it is possible to extend the focal length on the telephoto side without increasing the diameter of the front lens very much, but to increase the angle of view on the wide-angle side. If it is widened, the diameter of the front lens becomes large, making it impractical.

Although the zoom lens having the above five groups can make the diameter of the front lens relatively small, it has a drawback that the overall length becomes long. Also, due to extreme darkening at the telephoto end, an aspheric surface must be arranged in the first lens group in order to correct spherical aberration at the telephoto end, but the processing cost of the aspheric surface is high, Since the total number of lenses is large, there is a problem that the manufacturing cost is high.

Further, in a consumer video camera,
It is rare that the zooming effect during recording requires a continuous magnification of 50 times or more. In other words, there is a tendency that priority is given to a wider angle of view on the wide-angle side, smaller size, better portability, and lower manufacturing cost than the function of continuous high magnification, and the super-telephoto effect can be easily obtained when necessary. It is enough if it can be realized.

[0013]

SUMMARY OF THE INVENTION In view of the above problems, the present invention covers an extremely wide zoom range by switching between a wide-angle state, a standard state, and a telephoto state with a focal length range switch. It is another object of the present invention to provide a zoom lens which is small in size, has good portability, and is inexpensive to manufacture, and an imaging apparatus using the zoom lens.

[0014]

In order to solve the above problems, a zoom lens according to the present invention comprises, in order from the object side, a first lens group having a positive refractive power and a fixed position at all times; Which mainly performs zooming by moving on the optical axis.
A lens group, a third lens group having a positive refractive power and a fixed position at all times, and a fourth lens group having a positive refractive power and moving on the optical axis to correct and focus on fluctuations in image position. And a main lens system having a negative refractive power and retracted outside the optical path in a standard state. In use, the main lens system is inserted into the image side of the fourth lens group so that the optical axis coincides with the main lens system. A fifth lens group functioning as a variable power auxiliary lens that shifts the focal length range to the telephoto side and sets the telephoto state, and the fifth lens group is a cemented lens of a convex lens and a concave lens or a concave lens and a convex lens in order from the object side. Where f3 is the focal length of the third lens group, f5 is the focal length of the fifth lens group, β5 is the lateral magnification of the fifth lens group, and n5n is the refraction at the d-line of the concave lens of the fifth lens group. Rate, n5p to the d-line of the convex lens in the fifth lens group Ν5n is the Abbe number at the d-line of the concave lens of the fifth lens group, ν5p is the Abbe number at the d-line of the convex lens of the fifth lens group, and r5,3 is the fifth.
If the radius of curvature of the third surface counted from the object side of the lens group is 0.4 <| f5 / f3 | <0.7, 1.25 <β5 <
2.1, 0.1 <n5n-n5p, 10 <ν5n-ν5p, 0.2
<| R5,3 / f5 | <0.6.

A second zoom lens according to the present invention includes, in order from the object side, a first lens group whose position is fixed at all times, a second lens group which mainly performs zooming by moving on the optical axis,
A main lens system including a third lens group whose position is fixed at all times, a fourth lens group that moves on the optical axis and corrects and focuses on fluctuations in the image position, and is retracted outside the optical path in a standard state. In use, it is inserted so that the optical axis is coincident with the image side of the fourth lens group, and functions as a variable power auxiliary lens that shifts the focal length range of the main lens system to the telephoto side to bring the telephoto state. The first lens group is composed of five lens groups and has a zoom ratio of 15 or more. The first lens group has a positive refractive power and, in order from the object side, a cemented lens of a concave meniscus lens and a convex lens and a convex meniscus lens. Consisting of
fT is the focal length at the telephoto end of the main lens system in the standard state and the telephoto state, f1 is the focal length of the first lens group, ΔP1,2 is the anomalous dispersion of the second lens, counting from the object side of the first lens group. Assuming that ΔP1,3 is a value indicating the anomalous dispersion of the third lens, counting from the object side of the first lens group,
1.65 <fT / f1 <2.7, 0.035 <ΔP1,2, −
The condition of 0.003 <ΔP1,3 <0.003 is satisfied.

A third zoom lens system according to the present invention includes, in order from the object side, a first lens unit having a positive refractive power and a fixed position at all times, and moving on the optical axis having a negative refractive power. A second lens group that mainly performs zooming, a third lens group that has a positive refractive power and a fixed position at all times, and has a positive refractive power and moves on the optical axis to change the image position. The main lens system consisting of a fourth lens group that performs correction and focusing, and has a negative refractive power and is retracted outside the optical path in a standard state, and the optical axis coincides with the image side of the fourth lens group when used. And a fifth lens unit functioning as a variable power auxiliary lens which shifts the focal length range of the main lens system to the telephoto side to bring it into the telephoto state, and has a standard state on the object side of the first lens group. In the negative refraction functioning as a zooming auxiliary lens that is retracted outside the optical path Is disposed, and when the fifth lens group is retracted out of the optical path, the sixth lens group is inserted so that the optical axes coincide with each other, and the second lens group is moved to the position at the wide-angle end. Thereby, the focal length of the entire lens system is shifted to a wide-angle state shorter than that at the wide-angle end in the standard state.

Therefore, by switching between a wide-angle state, a standard state, and a telephoto state with a focal length range changeover switch or the like, a zoom which is small in size, has good portability, and has a low manufacturing cost while covering an extremely wide zoom range. It becomes possible to provide a lens.

The image pickup apparatus according to the present invention mainly includes a first lens unit having a positive refractive power and a fixed position at all times and a negative refractive power and moving on the optical axis in order from the object side. A second lens group for performing zooming, a third lens group having a positive refractive power and a fixed position at all times, and a third lens group having a positive refractive power and moving on the optical axis to correct the fluctuation of the image position. 4th Focusing
A zoom lens composed of a main lens system including a lens group, a fifth lens group having a negative refractive power, and a sixth lens group having a negative refractive power, each functioning as a variable power auxiliary lens, is used as an imaging lens. The fifth lens group is retracted out of the optical path in the standard state, and is inserted into the image side of the fourth lens group so that the optical axis coincides with the image side of the fourth lens group in use, so that the focal length range of the main lens system is shifted to the telephoto side. The sixth lens group has a function of moving out of the optical path in a standard state, and has a function of moving the telephoto state to the telephoto state. When the fifth lens group is in the state of retracting out of the optical path, the sixth lens group is located on the object side of the first lens group. A function to shift the focal length of the entire lens system to a wide-angle state shorter than that at the wide-angle end in a standard state by moving the second lens group to the position at the wide-angle end and inserting the second lens group to the position at the wide-angle end. Also have It is.

Therefore, by switching between a wide-angle state, a standard state, and a telephoto state with a focal length range changeover switch or the like, a zoom that covers a very wide zoom range, is small in size, has good portability, and has a low manufacturing cost. An imaging device using a lens can be provided.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, common items of the present invention will be described.

According to the present invention, the focal length of the main lens system is switched between a wide-angle state, a standard state, and a telephoto state by a focal length range changeover switch or the like. It is an object of the present invention to provide a zoom lens that is good and has a low manufacturing cost.

As shown in FIGS. 1 to 3 and FIGS. 11 to 13, the zoom lens according to the present invention has, in order from the object side, a first lens group GI having a positive refractive power and a fixed position at all times. A second lens group GII having a negative refractive power and mainly performing zooming by moving on the optical axis; a third lens group GIII having a positive refractive power and a fixed position at all times; A main lens system including a fourth lens group GIV that has a refractive power of and moves along the optical axis to correct and focus on fluctuations in image position;
It has a negative refractive power and is retracted out of the optical path in the standard state. In use, it is inserted into the image side of the fourth lens group GIV so that the optical axis coincides with it, and the focal length range of the main lens system is set to the telephoto side. And a fifth lens group GV functioning as a variable power assisting lens that changes to a telephoto state.

The second lens group GII and the third lens group GII
A stop IR is disposed at a position closer to the third lens group GIII between the lens group I and the fourth lens group GIV and the image plane IMG in a standard state.
Between the fifth lens group GV and the image plane IMG in the telephoto state.
L is provided.

The fifth lens group GV is, in order from the object side,
A cemented lens of the convex lens L5,1 and the concave lens L5,2, or a cemented lens of the concave lens L5,1 and the convex lens L5,2, f3
Is the focal length of the third lens group GIII, and f5 is the fifth lens group GV.
, Β5 is the lateral magnification of the fifth lens group GV, n5n is the refractive index at the d-line of the concave lens of the fifth lens group GV, n5p is the refractive index at the d-line of the convex lens of the fifth lens group GV, ν5
n is the Abbe number at the d-line of the concave lens of the fifth lens group GV, ν5p is the Abbe number at the d-line of the convex lens of the fifth lens group GV, and r5,3 is the third from the object side of the fifth lens group GV. Assuming the curvature radius of the surface, 0.4 <| f5 / f3 | <0.7 (conditional expression 1), 1.25 <β5 <2.1 (conditional expression 2), 0.1 <n5n−n5p (condition (Equation 3) 10 <ν5n−ν5p (conditional expression 4) and 0.2 <| r5,3 / f5 | <0.6 (conditional expression 5)

The first lens group GI includes, in order from the object side, a cemented lens of the concave meniscus lens L1,1 and the convex lens L1,2 and a convex meniscus lens L1,3.
ΔP1,2 is a value indicating the anomalous dispersion of the second lens (convex lens L1,2) counting from the object side of the first lens group, and n1,3 is the first.
If the refractive index at the d-line of the third lens (convex meniscus lens L1,3) counted from the object side of the lens group is 0.008 <ΔP1,2 (conditional expression 6), 1.67 <n1,3 ( It is desirable to satisfy each condition of the conditional expression 7).

A value ΔP indicating the anomalous dispersion of the second lens (convex lens L1, 2) counted from the object side of the first lens group.
The value ΔPi, j indicating the anomalous dispersion of the j-th lens counted from the object side of the i-th lens group, such as 1, 2, etc., is defined as P = (ng−nF) / (nF−nC). When the values of various glasses are plotted on a graph with the axis P and the horizontal axis Abbe number ν, the value of the arbitrary glass type g serving as a sample, that is, the value of the i-th lens counted from the object side of the i-th lens group is , The vertical deviation from a standard line passing through the values of glass types C7 and F2. Here, ng, nF and nC indicate the refractive indexes of arbitrary glass types g, C7 and F2, respectively.

Particularly, in a zoom lens having a zoom ratio of 15 times or more, the first lens group GI has a positive refractive power, and the concave meniscus lens L1,1 and the convex lens L1,2 in order from the object side. Cemented lens and convex meniscus lens L
FT is the focal length of the main lens system at the telephoto end in the standard state and the telephoto state, f1 is the focal length of the first lens group GI, and ΔP1,2 is the object side of the first lens group GI. Is a value indicating the anomalous dispersion of the second lens (convex lens L1,2), ΔP1,3 is the anomalous dispersion of the third lens (convex meniscus lens L1,3) counted from the object side of the first lens group If the value indicates the property, 1.65 <fT / f1 <2.7 (conditional expression 8), 0.035 <ΔP1,2 (conditional expression 9), −0.003 <ΔP1,3 <0.003 ( It is desirable to satisfy each condition of the conditional expression 10).

In the zoom lens having a zoom ratio of 15 times or more, if conditional expression 9 is satisfied, a surface other than the cemented surface of the convex lenses L1, 2 of the first lens group GI is It is desirable to form a thin resin layer so that the surface has a spherical shape or an aspherical shape.

The F number at the wide-angle end of the main lens system in the telephoto state is determined by the effective diameter of the fifth lens group GV.

That is, the fifth lens group GV is replaced with the fourth lens group GI
By increasing the focal length by inserting it on the image side of V, not only the chromatic aberration at the telephoto end but also the chromatic aberration correction situation changes at the wide-angle end, and a good balance is likely to be lost. Therefore, the F number at the wide-angle end is set such that the effective diameter of the fifth lens group GV is set to be small to limit the light flux, so that it becomes darker than passing the light flux all the way to the full aperture diameter and balance aberration correction. It is desirable to do so. still,
The F-number at the telephoto end is determined by being limited by the effective diameter of the first lens group GI, as in the case of the standard state.

Further, the zoom lens of the present invention has a negative refractive power and is retracted outside the optical path in a standard state, and is inserted into the fourth lens group GIV so that the optical axis coincides with the image side in use. The fifth lens functioning as a variable power auxiliary lens that shifts the focal length range of the main lens system to the telephoto side to bring it into a telephoto state.
On the object side of the first lens group GI, a sixth lens group GVI having a negative refractive power and functioning as a variable power auxiliary lens which is retracted out of the optical path in a standard state is disposed on the object side of the first lens group GI. When the fifth lens group GV is retracted out of the optical path, the sixth lens group GVI is inserted so that the optical axes thereof coincide with each other, and the second lens group GII is moved to the position at the wide-angle end. The focal length of the system is shifted to a wide-angle state shorter than that at the wide-angle end in the standard state.

The sixth lens group GVI is constituted by a concave single lens L6,1, f6 is the focal length of the sixth lens group GVI, fW is the focal length at the wide-angle end of the main lens system in a standard state, and r6,2 is If the radius of curvature of the second surface counted from the object side of the sixth lens group GVI and ν6 is the Abbe number of the concave single lens L6,1 constituting the sixth lens group, 16 <| f6 / fW | <25, (Conditional expression 11), 0.25 <| r6,2 / f6 | <0.45 (conditional expression 12), and 46 <ν6 (conditional expression 13).

The conditions defined by the above conditional expressions 1 to 13 will be described below.

Conditional expression 1 defines the refracting power of the fifth lens group GV for exhibiting the telephoto effect.

That is, when the value of | f5 / f3 | exceeds the upper limit, the effect of shifting the focal length of the main lens system to the telephoto side is weakened. Conversely, the value of | f5 / f3 | Below this value, the Petzval sum is negative and the absolute value is large, making it difficult to correct sagittal field curvature.

Conditional expression 2 defines conditions relating to the telephoto effect of the fifth lens group GV, as in conditional expression 1.

That is, when the value of β5 exceeds the upper limit value, the axial chromatic aberration mainly generated from the first lens group GI becomes smaller than the fifth value.
The enlargement by the lens group GV deteriorates the secondary spectrum at the telephoto end, and inevitably deteriorates the image quality. Conversely, when the value of β5 is equal to or less than the lower limit, the effect of shifting the focal length of the main lens system to the telephoto side is weakened.

Conditional expression 3 defines conditions for strongly exerting the telephoto effect by the fifth lens group GV within the range defined by conditional expressions 1 and 2.

That is, by making the refractive index of the concave lens of the fifth lens group GV sufficiently higher than the refractive index of the convex lens, the Petzval sum can be reduced in the negative direction even if a little. Can be made closer to the upper limit.

Conditional expression 4 defines the range of the glass material applied to the fifth lens group GV together with conditional expression 3.
By making the Abbe number of the concave lens larger than that of the convex lens, achromatism of the fifth lens group GV is realized, and fluctuation of chromatic aberration due to retreat of the fifth lens group GV from the optical axis can be suppressed.

Therefore, from the conditions of the conditional expressions 3 and 4, the glass material used for each lens of the fifth lens group GV is naturally determined.

Conditional expression 5 defines a shape for suppressing the aberration generated from the fifth lens group GV to a small value. The fifth lens group GV has a shape of a cemented convex meniscus lens having a strong concave surface facing the image side as a whole, defines the curvature of the concave surface, and combines the conditions with the conditions specified in conditional expressions 1 to 4, respectively. , The shape of the fifth lens group GV is substantially determined.

That is, when the value of r5,3 / f5 is equal to or more than the upper limit, the meridional field curvature becomes under side, and correction becomes difficult. Conversely, if the value of r5,3 / f5 is equal to or less than the lower limit, the Petzval sum increases to the negative side by the fifth lens group GV, and it becomes difficult to correct sagittal field curvature.

Conditional expression 6 defines conditions relating to the secondary spectrum of chromatic aberration at the telephoto end of the main lens system, which becomes a problem when the focal length is enlarged by the fifth lens group GV.

That is, if the value ΔP indicating the anomalous dispersion of the convex lens of the first lens group GI is set to the plus side from the standardity, the secondary spectrum of the chromatic aberration can be improved. However, in general, a glass material having a large ΔP and a large Abbe number tends to have a low refractive index, but among the convex lenses in the first lens group, a convex lens (the second lens group) having a small influence on aberration correction even if the refractive index is lowered. 2
For example, when a lens material FC5 having a ΔP of 0.0091 (manufactured by HOYA CORPORATION) is used for the lens L1, 2), the effect is improved.

In the conditional expression 7, the refractive index of the convex lens (second lens L1, 2) of the first lens group GI is reduced by the conditional expression 6, and it becomes difficult to correct the spherical aberration at the telephoto end of the main lens system. Accordingly, the conditions for increasing the refractive index of the convex meniscus lens (third lens L1, 3) to facilitate monochromatic aberration correction are defined.

That is, a glass material having a high refractive index and a large Abbe number generally has a negative value ΔP showing the above-mentioned dispersibility and a large absolute value, and is somewhat disadvantageous for improving the secondary spectrum. However, the condition defined by the conditional expression 7 is required from the balance between the manufacturing cost and the improvement of the secondary spectrum.

Conditional expression 8 defines conditions for judging whether a glass material having anomalous dispersion is positively used for correcting the secondary spectrum.

That is, when the value of fT / f1 becomes equal to or less than the lower limit,
In the glass material used for the convex lens (second lens L1, 2) of the first lens group GI, practically sufficient performance can be obtained if at least the condition defined by the conditional expression 6 is satisfied. When the value of / f1 is larger than the lower limit, sufficient performance is not always obtained. Therefore, by selecting a glass material so as to satisfy the condition defined by the conditional expression 9, the secondary spectrum can be remarkably improved. Also, fT /
As the value of f1 approaches the upper limit, it is desirable to darken the F-number at the telephoto end of the main lens system to make the deterioration of the secondary spectrum inconspicuous, but if the value of fT / f1 exceeds the upper limit, Even if the F-number is darkened, the deterioration of the performance becomes remarkable and often causes a practical problem.

Forming the resin layer on the surface of the convex lens (second lens L1, 2) of the first lens group GI further satisfies the above-mentioned problems relating to the secondary spectrum, as defined by the conditional expressions 9 and 10. The purpose is to improve and to suppress the increase in the cost as much as possible.

That is, the convex lens of the first lens group GI (the second lens
For example, when the glass material FCD1 having a value of ΔP of 0.0374 is used for the lens L1, 2), the secondary spectrum is significantly improved. The concave lens (first lens L1,1) of the first lens group GI is made of a glass material having a small Abbe number, for example, FDS.
When 90 is used, the chromatic aberration can be overcorrected by the concave lens (first lens L1,1) and the convex lens (second lens L1,2), so that the convex lens (L1,3) is set to the condition defined by the conditional expression 7. , The chromatic aberration can be corrected even if the Abbe number is slightly reduced, and a glass material having ΔP close to the standard line can be selected. For example, NbF with ΔP of −0.0021
D10, NbFD15 where ΔP is zero, ΔP is 0.0020
BaFD8, BaFD7 with ΔP of 0.0027 and ΔP
However, BaFD15 having -0.0015 has a high refractive index, which is advantageous for correcting monochromatic chromatic aberration, and is suitable as having little adverse effect on the secondary spectrum.

By the way, the glass material such as the glass material FCD1 and the like having low dispersion and anomalous dispersibility is generally liable to cause scratches during the polishing step and latent scratches that become apparent due to ultrasonic cleaning or the like. In the same manner as in the above, a time-consuming process must be performed because the polishing operation cannot be performed. Further, since the coefficient of linear expansion is as large as about 1.8 times FC5, when coating with a vacuum evaporation machine,
If the vacuum is broken after heating and coating the glass material, the glass material may be quenched by air and cracked.To prevent this, it is necessary to gradually cool the glass material. And the cost of processing the glass material increases.

The convex lens of the first lens group GI (the second lens L
Even if there is a polishing flaw, the bonding surface of (1) and (2) is buried with an adhesive to make the flaw inconspicuous, and no coating is required, so that the above-mentioned cost increase factor can be avoided.
Therefore, similarly to the case of the cemented surface, the convex lens (the second lens
At the room temperature, UV-curable resin, etc., is used to cover the surface other than the joint surface of L1, 2) with a thin layer of resin to bury and hide the scratches during the above polishing process and latent scratches that become apparent due to ultrasonic cleaning. By vapor-depositing the resin layer, it is possible to eliminate the step of gradually cooling the heated glass material, which is a factor of high cost. The resin layer is the same as that used for forming a so-called composite aspherical surface, but the surface shape may be either spherical or aspherical for the purpose of reducing the processing cost of the glass material.

Conditional expression 11 represents a virtual image of a subject at infinity,
The sixth lens group GVI defines a condition of how far from the first lens group GI.

That is, when the value of f6 / fW exceeds the upper limit,
The change in magnification when switching to the wide-angle state is small, and the object of the present invention cannot be achieved. Conversely, if the value of f6 / fW is equal to or less than the lower limit, it becomes difficult to correct barrel-shaped distortion generated by the sixth lens group GVI and curvature of the image plane to the over side. In addition, since the main lens system is used in the macro area at the wide-angle end, the aberration of a short-distance subject is significantly deteriorated. Therefore, the value of f6 / fW exceeds the lower limit, that is, the virtual image is converted to the first lens. It is not preferred to approach group GI.

Conditional expression 12 is a condition for defining the surface shape of the sixth lens group GVI.

That is, when the value of | r6,2 / f6 | is equal to or larger than the upper limit, barrel-shaped distortion becomes large and correction becomes difficult. Conversely, if the value of | r6,2 / f6 | is less than or equal to the lower limit, the curvature of the image plane toward the over side becomes large, and correction becomes difficult.

Conditional expression 13 defines a condition for constituting the sixth lens group GVI by a single lens and for suppressing deterioration of chromatic aberration of magnification within a practical range.

That is, when the Abbe number is small, a short wavelength image blurs inward to the inside of the screen. To make this inconspicuous, it is possible to some extent to make the chromatic aberration of magnification at the wide-angle end in the standard state blur a short wavelength to the outside of the screen in advance, but if the Abbe number of the sixth lens group is too small, the standard state will be reduced. Chromatic aberration of magnification between the wide-angle end and the wide-angle state cannot be balanced.

Next, an image pickup apparatus using the zoom lens 1 or 1A as an image pickup lens will be described.

As shown in FIG. 21, the imaging device 10 of the present invention comprises, in order from the object side, a first lens group GI having a positive refractive power and a fixed position at all times, and an optical axis having a negative refractive power and an optical axis. A second lens group GII which mainly performs zooming by moving upward, and a third lens group GIII which has a positive refractive power and has a fixed position at all times.
And a main lens system 2 or 2A comprising a fourth lens group GIV having a positive refractive power and moving on the optical axis to correct and focus on fluctuations in the image position, and a negative lens functioning as a zooming auxiliary lens. Using a zoom lens 1 or 1A constituted by a fifth lens group GV having a refractive power of and a sixth lens group GVI having a negative refractive power as an imaging lens;
The fifth lens group GV is retracted out of the optical path in the standard state, and is inserted into the image side of the fourth lens group GIV so that the optical axis coincides with the fourth lens group GIV in use, so that the focal length range of the main lens system 2 or 2A is adjusted. The sixth lens group GVI has a function of retracting out of the optical path in the standard state, and has a function of shifting to the telephoto side to shift to the telephoto state. By inserting the second lens group GII to the position at the wide-angle end and inserting the second lens group GII to the position at the wide-angle end, the focal length of the entire lens system is set higher than that at the wide-angle end in the standard state. Also has a function of shifting to a short wide-angle state.

In the image pickup apparatus 10, the position where the fourth lens group GIV is closest to the image side when focusing on infinity in the standard state and the fifth lens group GV inserted in the telephoto state are the optical axis. Therefore, when the fifth lens group GV is inserted, it is necessary to first move the fourth lens group GIV to the object side.

Accordingly, the image pickup apparatus 10 is provided with a position detecting means 11 for detecting the current position of the fourth lens group GIV and a driving means 12, and further includes a fifth lens group GV which is a telephoto auxiliary lens. Position detecting means 13 and driving means 14 for detecting insertion on the optical axis and retreating off the optical axis are also provided. Further, it also has a control circuit 15 for controlling the position detecting means 11 and 13 and the driving means 12 and 14, and a focal length range changeover switch 16.

When shifting from the standard state to the telephoto state, the control circuit 15 issues an instruction to the driving means 12 and 14 in accordance with the instruction of the focal length range changeover switch 16 and firstly moves the fourth lens group GIV to the object side. The main lens systems 2 and 2A are moved by securing a space in which the fifth lens group GV can be inserted, and then inserting the fifth lens group GV into the space.
The operation is controlled so that the focus is adjusted by appropriately moving the fourth lens group GIV.

When shifting from the telephoto state to the standard state, on the contrary, the control circuit 15 issues an instruction to the driving means 12 and 14 to first retract the fifth lens group GV out of the optical path. The fourth lens group GIV retreats (moves to the image side)
After securing a space for the fourth lens group G
Each operation is controlled so that focusing can be performed by retracting the IV.

The control circuit 15 calculates the relative positional relationship between the second lens group GII for mainly performing zooming and the fourth lens group GIV for focusing in advance with respect to a plurality of object distances and stores the data. The data recorded in the storage unit 17 can be operated so as to prevent the focus from moving during zooming at an arbitrary distance. The second lens group GII and the fourth lens group G stored in the storage unit 17 are stored.
The data of the relative positional relationship with the IV is recorded as separate data corresponding to the standard state and the telephoto state, and these data are selectively used by the control circuit 15 in response to the operation of the focal length range switch 16. Is desirable.

However, in order to record data relating to each of the standard state and the telephoto state of the zoom lens 1 or 1A in the storage means 17 for supplying data to the control circuit 15, a large capacity is required for the storage means 17. Required. When comparing the data in the standard state and the data in the telephoto state, the data in the telephoto state is approximately similar to the trajectory of the fourth lens group GIV being translated toward the object side from the data in the standard state. If only the data and the correction coefficient for correcting the error are recorded, and the other data is required, the data is calculated based on one of the data by using the correction coefficient. Can be saved.

Further, the image pickup apparatus 10 has a video signal processing circuit 18 for extracting a valid pixel range from the total pixel range of the image pickup device and forming a video screen as a function of correcting a camera shake of a moving image. Then, the video signal processing circuit 18 detects the shaking of the imaging device 10 by the angular velocity sensor, calculates the focal length of the zoom lens 1 or 1A and the data of the angular velocity sensor, and calculates the data within the total pixel range of the imaging element. The position of the second lens group GII is configured to correct the fluctuation of the image by moving the position from which the effective pixel range is extracted at any time, and to determine whether the focal length range switch 16 is in the standard state or the telephoto state. It is desirable to switch the value of the focal length with respect to and perform the calculation to optimize the amount of shake correction.

Since the image pickup apparatus 10 has the sixth lens group GVI functioning as a wide-angle auxiliary lens as described above, the focal length range changeover switch 16 is set in three positions: a standard state, a telephoto state, and a wide-angle state. It can be switched.

Then, the focal length range switch 1
When the sixth lens group is switched to the wide-angle state, the sixth lens group GVI becomes the first lens group.
When the main lens system 2 or 2A is inserted into the position on the object side of the lens group GI so that the optical axis coincides with the main lens system 2 and the fifth lens group GV is inserted on the image side of the fourth lens group GIV, The second lens group GII is moved to the position at the wide-angle end and fixed, and the fourth lens group GIV is further extended from the position where it is focused at infinity, so that the sixth lens group GII is retracted.
It is desirable to control a series of operations of each unit so as to focus on a virtual image of a subject viewed through VI.

The sixth lens group GVI includes the main lens system 2 or 2
A position retracted from the optical path of A and a position where the optical axis coincides with the main lens system 2 or 2A are configured to be switched by a driving unit 19 composed of a toggle spring or the like. It moves mechanically in conjunction with the switching operation between the state and the wide-angle state.

As for the position information of the sixth lens group GVI, only the position information of the focal length range changeover switch 16 in the switching operation between the standard state and the wide angle state is transmitted to the control circuit 15, and the control circuit 15 controls the position information. It is desirable that the imaging apparatus 10 be configured to be able to appropriately switch among three magnification states, a standard state, a telephoto state, and a wide-angle state, according to an instruction.

Hereinafter, numerical examples 1 and 2 that embody the zoom lens of the present invention will be described.

In the following description, “ri, j” is the i-th
Radius of curvature of the j-th surface counted from the object side of the lens group,
“Ri, j ′” is the radius of curvature of the surface of the thin resin layer formed on the ri, j surface, and “di, j” is the j-th surface and the (j + 1) -th surface counted from the object side of the i-th lens unit. "Di, j '" is the thickness of the thin resin layer formed on the ri, j surface, "dIR" is the air gap between the stop IR and the most object-side surface of the third lens group GIII, “DFL” is the surface interval of the filter FL, and “ni, j” is the j-th lens (Li,
The refractive index at d-line of the material constituting j), "ni, j '" is the refractive index at d-line of the resin layer formed on the lens Li, j,
“NFL” is the refractive index of the material constituting the filter FL at d-line, “νi, j” is the Abbe number of the material constituting the lens Li, j, and “νi, j ′” is the lens Li, j. The Abbe number of the material forming the resin layer and “νFL” indicate the Abbe number of the material forming the filter FL.

Assuming that “xi, j” is the depth of the aspheric surface and “H” is the height from the optical axis, xi, j = H ² / ri, j ｛1 + √ (1- H ² / ri, j ² )｝ + ΣA
jH ^{j is} defined.

The zoom lens 1 according to Numerical Example 1 is
It has a configuration as shown in FIG.

In the main lens system 2, the first lens group GI includes, in order from the object side, a cemented lens of a concave meniscus lens L1.1 and a convex lens L1,2 and a convex meniscus lens L1,3. A spherical resin layer is formed on the image-side surfaces r1 and r3, and the second lens group GII is a concave lens in order from the object side.
L2,1 and a cemented lens of a concave lens L2,2 and a convex lens L2,3, the third lens group GIII is composed of a convex lens L3,1,
The fourth lens group GIV is composed of three cemented lenses of a convex lens L4,1, a concave lens L4,2, and a convex lens L4,3 in order from the object side.

Further, a fifth telephoto auxiliary lens is used.
The lens group GV includes, in order from the object side, a cemented lens of a convex lens L5,1 and a concave lens L5,2. The sixth lens group GVI used as a wide-angle auxiliary lens includes a concave meniscus lens L6,1.
Consisting of:

FIG. 2 is a diagram showing the telephoto state of the zoom lens 1, and shows the fourth lens group G from the standard state shown in FIG.
FIG. 3 shows a state in which the fifth lens group GV is inserted so that the optical axis coincides with the main lens system 2 after the IV is moved to the object side.
FIG. 6 is a diagram showing a wide-angle state of the zoom lens 1, in a state where the fifth lens group GV is retracted outside the optical path, and
I is inserted into the object side of the first lens group GI, and the second lens group GII is moved to the wide-angle end position and fixed so that zooming cannot be performed, so that focusing is performed by the fourth lens group GIV. It shows the status.

Table 1 shows numerical values of the zoom lens 1 in the standard state shown in FIG. Since the fifth lens group GV and the sixth lens group GVI are not used in the standard state, only the numerical values of the main lens system 2 are shown.

[0082]

[Table 1]

Table 2 shows the fourth, sixth, eighth and tenth order aspherical coefficients A of the surfaces r3,1 and r4,1 constituted by the aspherical surfaces.
4, A6, A8 and A10 are shown, respectively. Note that “E” in Table 2 means an exponential expression with a base of 10, and for example, “E-03” indicates “× 10 ⁻³ ” (the same applies to the following aspheric coefficient). The same applies to the table).

[0084]

[Table 2]

Table 3 shows the focal length, the F-number, the angle of view (2ω), and the variable distance between the zoom lens 1 with the zooming operation in the standard state of the zoom lens 1 at the wide angle end, the intermediate focal position and the telephoto end. d1,5, d2,5, d
The values of 3,2 and d4,4 are shown.

[0086]

[Table 3]

Table 4 shows numerical values of the zoom lens 1 according to Numerical Example 1 in the telephoto state shown in FIG. In the telephoto state of the zoom lens 1, the only difference is that the variable distances d3,2 and d4,4 and the components of the fifth lens group GV are different from those in the standard state shown in Table 1; , 2 and subsequent figures are also shown (Table 5 is also the same).

[0088]

[Table 4]

Table 5 shows the focal length at the wide-angle end, the intermediate focal position and the telephoto end of the zoom lens 1 in the telephoto state, the F-number, the angle of view (2ω), and the surface distance d3,2 whose numerical value changes with the zooming operation. And d4,4 are shown.

[0090]

[Table 5]

Table 6 shows numerical values of the zoom lens 1 according to Numerical Example 1 in the wide-angle state shown in FIG. Note that, in the wide angle state of the zoom lens 1, the sixth lens group GVI is added to the object side of the surface r1,1 as compared with the standard state shown in Table 1, so that the surface r1,1 Only the numerical value of is shown.

[0092]

[Table 6] Table 7 shows the focal length, F-number, angle of view (2ω), and variable intervals d1,5, d2, of the zoom lens 1 in the wide angle state.
The values of 5, d3,2 and d4,4 are shown.

[0093]

[Table 7]

FIGS. 2 to 6 show the zoom lens 1 respectively.
2 shows the spherical aberration, astigmatism, and distortion at the wide angle end, the intermediate focal position, and the telephoto end, respectively, in the standard state.

FIGS. 7 to 9 show the spherical aberration, astigmatism, and distortion at the intermediate focal position and the telephoto end of the zoom lens 1 in the telephoto state, respectively.

FIG. 10 shows the spherical aberration, astigmatism, and distortion of the zoom lens 1 in the wide-angle state, respectively.

In the spherical aberration diagram, the solid line is the d-line (wavelength
587.6 nm), the dashed line indicates the value at the g-line (wavelength 435.8 nm), the dashed line indicates the value at the C-line (wavelength 656.3 nm). In the astigmatism diagram, the solid line is the sagittal image plane, and the dashed line is the meridional image. It shows the value on the surface (the same applies to the following aberration diagrams).

Table 8 shows the numerical values of the conditional expressions 1 to 13 of the zoom lens 1 in Numerical Example 1 and the numerical values related thereto.

[0099]

[Table 8]

The zoom lens 1A according to Numerical Example 2 has a configuration as shown in FIG.

In the main lens system 2A, the first lens group GI includes, in order from the object side, a cemented lens of a concave meniscus lens L1.1 and a convex lens L1, 2 and a convex meniscus lens L1, 3; The third lens is composed of a concave lens L2,1 and a cemented lens of the concave lens L2,2 and the convex lens L2,3 in order from the object side.
The lens group GIII includes a convex lens L3,1, and the fourth lens group GIV includes, in order from the object, a cemented lens of a convex lens L4,1, a concave lens L4,2, and a convex lens L4,3.

A fifth telephoto auxiliary lens is used.
The lens group GV includes, in order from the object side, a cemented lens of a convex lens L5,1 and a concave lens L5,2. The sixth lens group GVI used as a wide-angle auxiliary lens has a concave meniscus lens L6,1.
Consisting of:

FIG. 12 is a view showing a telephoto state of the zoom lens 1A. After the fourth lens group GIV is moved to the object side from the standard state shown in FIG. 11, the fifth lens group GV is moved to the main lens system. FIG. 13 is a view showing a wide-angle state of the zoom lens 1A, wherein the fifth lens group GV is retracted out of the optical path, and the sixth lens group GVI is shown. Is inserted into the object side of the first lens group GI, and the second lens group GII is moved to the wide-angle end position and fixed so that zooming cannot be performed.
5 shows a state in which focusing is performed.

Table 9 shows numerical values of the zoom lens 1A according to Numerical Example 2 in the standard state shown in FIG. In the standard state, since the fifth lens group GV and the sixth lens group GVI are not used, only the numerical values of the main lens system 2A are shown.

[0105]

[Table 9]

Table 10 shows the surface r3,1 constituted by an aspherical surface.
And the fourth, sixth, eighth and tenth order aspherical coefficients A of r4,1
4, A6, A8 and A10 are shown, respectively.

[0107]

[Table 10]

Table 11 shows the focal length, F-number, field angle (2ω), and the distance d1,5 of the zoom lens 1A at the wide-angle end, the intermediate focal position, and the telephoto end in the standard state. , D2,5, d3,2 and d4,4
Are shown below.

[0109]

[Table 11]

Table 12 shows numerical values of the zoom lens 1A according to Numerical Example 2 in the telephoto state shown in FIG.
In the telephoto state of the zoom lens 2, the only difference is that the variable distances d3,2 and d4,4 and the components of the fifth lens group GV are different from those in the standard state shown in Table 9; ,
Only the numerical values after 2 are shown (the same applies to Table 13).

[0111]

[Table 12]

Table 13 shows the focal length at the wide-angle end, the intermediate focal position and the telephoto end of the zoom lens 1A in the telephoto state, the F-number, the angle of view (2ω), and the surface distance d3,2 whose numerical value changes with the zooming operation. And d4,4 are shown.

[0113]

[Table 13]

Further, Table 14 shows numerical values of the zoom lens 1A according to Numerical Example 2 in the wide angle state shown in FIG.
In the wide-angle state of the zoom lens 1A, the sixth lens group GVI is located on the object side of the surface r1,1 compared to the standard state shown in Table 9.
Is added to the configuration, only the numerical values up to the plane r1,1 are shown.

[0115]

[Table 14]

Table 15 shows the focal length, F-number, angle of view (2ω) and variable intervals d1,5, d2,5, d3,2 and d4,4 of the zoom lens 1A in the wide angle state.

[0117]

[Table 15]

FIGS. 14 to 16 show the spherical aberration, astigmatism and distortion at the wide-angle end, intermediate focal position and telephoto end of the zoom lens 1A in the standard state, respectively.

FIGS. 17 to 19 show the spherical aberration, astigmatism, and distortion at the intermediate focal position and the telephoto end of the zoom lens 1A in the telephoto state, respectively.

FIG. 20 shows the spherical aberration, astigmatism, and distortion of the zoom lens 1A in the wide-angle state, respectively.

Table 16 shows numerical values of the conditional expressions 1 to 13 of the zoom lens 1A in Numerical Example 2 and numerical values related to them.

[0122]

[Table 16]

As described above, the zoom lens of the present invention can easily switch the focal length of the main lens system between the standard state, the telephoto state, and the wide-angle state only by operating the focal length range switch. Therefore, in the telephoto state, the focal length from the wide-angle end to the telephoto end can be shifted to the telephoto side while the zoom ratio of the main lens system remains unchanged. In the wide-angle state, the focal length at the wide-angle end of the main lens system is wide-angle. It can be shifted to the side and used as a wide-angle lens with a wider angle of view than the wide-angle end in the standard state, so it is released from the inconvenience of carrying another lens and replacing it as necessary .

Specifically, the zoom lenses 1 and 1A shown in the numerical examples 1 and 2 are super-wide-angle lenses covering an angle of view of 80 ° or more in the wide-angle state, and at the telephoto end in the telephoto state. 1400mm in terms of a lens used for a camera using a general 35mm format film
, So that the total zoom ratio exceeds 50 times, and can cover from the super wide angle range to the super telephoto range.

When the diagonal dimension of the image pickup device is 2.5 mm, the zoom lenses 1 and 1A are extremely small, with the total length from the sixth lens group GVI to the image pickup device being about 75 mm. In addition, the lens has an extremely bright brightness of about F1.6.

Further, as is clear from the aberration diagrams, the zoom lenses 1 and 1A have various aberrations corrected in a well-balanced manner, and have a sufficiently high image quality as an imaging device, particularly a zoom lens used in a consumer video camera. Have achieved. In particular, by using a glass material having anomalous dispersion for the convex lenses L1 and L2 and covering the surface with a resin layer, it is possible to achieve both improvement of the secondary spectrum at the telephoto end and lower processing costs. Therefore, it can be mass-produced.

As described above, the zoom lens of the present invention satisfies all the necessary conditions by achieving a high zoom ratio, super wide angle, super telephoto, high image quality, small size and light weight, low cost and ease of use in a well-balanced manner. It is a lens for high-performance consumer video cameras.

Furthermore, in an image pickup apparatus using the zoom lens of the present invention as an image pickup lens, the fifth lens group and the sixth lens group, which are telephoto and wide-angle variable power auxiliary lenses, are attached to and detached from the optical axis of the main lens system. A series of operations required in connection with are controlled by an arithmetic circuit, and data relating to the relative positions of the fifth lens unit and the sixth lens unit and the fourth lens unit serving as the focus lens of the main lens system are stored in, for example, an electronic cam curve. Can be used by switching between the two stored for the standard state and the telephoto state, and using the same function as the conventional built-in extender system, even though it is an inner focus lens system. It becomes possible, and the main lens system is forcibly shifted to the wide-angle end and fixed by interlocking with the use of the sixth lens group, which is a wide-angle variable power auxiliary lens, thereby causing erroneous operation. Was and can also be prevented.

In the image pickup apparatus of the present invention, the auto-focus function and the camera shake correction function, which are essential for a consumer video camera, are automatically set to an optimum state in accordance with the operation of the focal length range switch. Was also possible.

In this embodiment, the sixth lens group is constituted by a single spherical lens. However, it is possible to improve distortion by using an aspherical surface, or to use an aspherical plastic lens. Can also be used to balance low cost with practical performance.

Further, the sixth lens group may be constituted by a plurality of lenses including at least one convex lens. For example, if a two-lens configuration including a convex lens and a concave lens is used, the degree of freedom in design increases, and it becomes possible to correct curvature of field, distortion, chromatic aberration of magnification, and the like in a well-balanced manner.

However, plastic lenses have the disadvantage that they are easily scratched during use and the like, and the scratches may be transferred when a small aperture is used, which is not preferable. It is preferable to make the sixth lens group a plurality of lenses in order to give the highest priority to performance. However, since the sixth lens group becomes thicker, a high magnification and a small size are required in a consumer video camera. It is difficult to achieve both.

The specific shapes and structures of the respective parts shown in the above-described embodiments are merely examples for embodying the present invention, and the technical scope of the present invention is not limited thereto. Should not be interpreted restrictively.

[0134]

As described above, the zoom lens according to the present invention comprises, in order from the object side, the first lens group having a positive refractive power and a fixed position at all times, and the first lens group having a negative refractive power and having a negative refractive power on the optical axis. A second lens group that mainly performs zooming by moving the lens, a third lens group that has a positive refractive power and a fixed position at all times, and an image that moves on the optical axis and has a positive refractive power. A main lens system comprising a fourth lens group for correcting position fluctuations and focusing, and having a negative refracting power and retracted out of the optical path in a standard state. A fifth lens unit which functions as a variable power auxiliary lens which is inserted so that the axes thereof coincide with each other and shifts the focal length range of the main lens system to the telephoto side to bring the lens into a telephoto state; In order, the cemented lens of the convex lens and the concave lens or the concave lens and the convex lens F3 is the focal length of the third lens group, f5 is the focal length of the fifth lens group, β5 is the lateral magnification of the fifth lens group, n5n is the refractive index at the d-line of the concave lens of the fifth lens group, n5p is the refractive index at the d-line of the convex lens of the fifth lens group, ν5n is the Abbe number at the d-line of the concave lens of the fifth lens group, ν5p is the Abbe number at the d-line of the convex lens of the fifth lens group, and r5,3 is the If the radius of curvature of the third surface counted from the object side of the five lens groups is 0.4 <0.4
| F5 / f3 | <0.7, 1.25 <β5 <2.1, 0.1
<N5n−n5p, 10 <ν5n−ν5p, 0.2 <| r5,3 / f5 |
The zoom lens can be easily switched between the standard state and the telephoto state because it satisfies each condition of <0.6. The zoom lens is small, has good portability, and has a low manufacturing cost while covering an extremely wide zoom range. Can be provided.

According to the second aspect of the present invention, the first
The lens group includes, in order from the object side, a cemented lens of a concave meniscus lens and a convex meniscus lens and a convex meniscus lens, and ΔP1,2 is anomalous dispersion of the second lens counted from the object side of the first lens group. Where n1,3 is the refractive index at the d-line of the third lens counted from the object side of the first lens group, 0.008 <ΔP1,2, 1.67.
Since the respective conditions of <n1, 3 are satisfied, both improvement of the secondary spectrum at the telephoto end and reduction of the processing cost can be achieved.

According to the third aspect of the present invention, the F-number at the wide-angle end of the main lens system in the telephoto state is the fifth.
Since it is determined by the effective diameter of the lens group, the aberration correction balance can be improved.

A second zoom lens according to the present invention includes, in order from the object side, a first lens group whose position is fixed at all times, a second lens group which mainly performs zooming by moving on the optical axis, and
A main lens system including a third lens group whose position is fixed at all times, a fourth lens group that moves on the optical axis and corrects and focuses on fluctuations in the image position, and is retracted outside the optical path in a standard state. In use, it is inserted so that the optical axis is coincident with the image side of the fourth lens group, and functions as a variable power auxiliary lens that shifts the focal length range of the main lens system to the telephoto side to bring the telephoto state. It consists of five lens groups,
The first lens group has a positive refracting power and a cemented lens of a concave meniscus lens and a convex lens and a convex meniscus lens in order from the object side. The focal length at the telephoto end of the main lens system in the state and the telephoto state, f1 is the focal length of the first lens group,
ΔP1,2 is a value indicating the anomalous dispersion of the second lens, counted from the object side of the first lens group, and ΔP1,3 is the value indicating the anomalous dispersion of the third lens, counted from the object side of the first lens group. Assuming values, 1.65 <fT / f1 <2.7, 0.035 <ΔP1,
2. Since the respective conditions of -0.003 <ΔP1,3 <0.003 are satisfied, for example, by switching between the standard state and the telephoto state with a focal length range changeover switch or the like, an extremely wide range of change can be achieved. It is possible to provide a zoom lens that is small, has good portability, and has low manufacturing cost while covering the double range.

In the invention described in claim 5, the first aspect
Since a thin resin layer is formed on the surface other than the joint surface of the convex lens of the lens group so that the surface has a spherical shape or an aspherical shape, manufacturing costs such as lens processing costs can be reduced.

A third zoom lens according to the present invention sequentially moves from the object side to a first lens group having a positive refractive power and a fixed position at all times, and moves on the optical axis having a negative refractive power. A second lens group that mainly performs zooming, a third lens group that has a positive refractive power and a fixed position at all times, and has a positive refractive power and moves on the optical axis to change the image position. The main lens system consisting of a fourth lens group that performs correction and focusing, and has a negative refractive power and is retracted outside the optical path in a standard state, and the optical axis coincides with the image side of the fourth lens group when used. And a fifth lens unit functioning as a variable power auxiliary lens which shifts the focal length range of the main lens system to the telephoto side to bring it into a telephoto state. In this state, the lens is retracted out of the optical path. Place a sixth lens group having a force,
When the fifth lens group is retracted out of the optical path, the sixth lens group is inserted so that the optical axes coincide with each other, and the second lens group is moved to the position at the wide-angle end. Is changed to a wide-angle state shorter than that at the wide-angle end in the standard state.For example, by switching between the wide-angle state, the standard state, and the telephoto state with a focal length range switch or the like, an extremely wide change state is obtained. It is possible to provide a zoom lens that is small, has good portability, and has low manufacturing cost while covering the double range.

In the invention described in claim 7, the sixth aspect is provided.
The lens group is composed of a concave single lens, f6 is the focal length of the sixth lens group, fW is the focal length at the wide-angle end of the main lens system in a standard state, and r6,2 is the number counted from the object side of the sixth lens group. When the radius of curvature of the second surface, ν6, is the Abbe number of the concave single lens constituting the sixth lens group, 16 <| f6 / fW | <
25, 0.25 <| r6,2 / f6 | <0.45, 46 <ν6
Are satisfied, it is possible to satisfactorily correct various aberrations in the wide-angle state.

The imaging apparatus according to the present invention is mainly changed in order from the object side by moving the first lens group having a positive refractive power and a fixed position at all times, and moving on the optical axis having a negative refractive power. A second lens group that performs magnification, a third lens group that has a positive refractive power and a fixed position at all times, and has a positive refractive power and moves on the optical axis to correct for fluctuations in image position and perform focusing. Imaging a zoom lens composed of a main lens system composed of a fourth lens group, and a fifth lens group having a negative refractive power and a sixth lens group having a negative refractive power, each functioning as a variable power auxiliary lens. Used as a lens, the fifth lens group is retracted out of the optical path in the standard state, and is inserted into the image side of the fourth lens group so that the optical axis coincides with the fourth lens group in use. Has the function of shifting to the telephoto side and shifting to the telephoto state, The sixth lens group is retracted out of the optical path in the standard state. When the fifth lens group is retracted out of the optical path, the sixth lens group is inserted into the first lens group so that the optical axis coincides with the object side. By moving the second lens group to the position at the wide-angle end, it has a function of shifting the focal length of the entire lens system to a wide-angle state shorter than that at the wide-angle end in the standard state. Super telephoto, high image quality,
It is possible to provide an imaging device optimal for a consumer video camera which achieves a balance between small size, light weight, low cost, and ease of use.

[Brief description of the drawings]

FIG. 1 shows Numerical Example 1 in an embodiment of a zoom lens according to the present invention, together with FIGS. 2 to 10, and is a diagram showing a lens configuration in a standard state.

FIG. 2 is a diagram illustrating a lens configuration in a telephoto state.

FIG. 3 is a diagram showing a lens configuration in a wide-angle state.

FIG. 4 is a diagram illustrating various aberrations at a wide angle end in a standard state.

FIG. 5 is a diagram illustrating various aberrations in an intermediate focal region in a standard state.

FIG. 6 is a diagram illustrating various aberrations at a telephoto end in a standard state.

FIG. 7 is a diagram illustrating various aberrations at a wide-angle end in a telephoto state.

FIG. 8 is a diagram illustrating various aberrations in an intermediate focal region in a telephoto state.

FIG. 9 is a diagram illustrating various aberrations at a telephoto end in a telephoto state.

FIG. 10 is a diagram illustrating various aberrations in a wide-angle state.

FIG. 11 shows Numerical Example 2 of the zoom lens according to the embodiment of the present invention, together with FIGS. 12 to 20, and shows the lens configuration in a standard state.

FIG. 12 is a diagram showing a lens configuration in a telephoto state.

FIG. 13 is a diagram showing a lens configuration in a wide-angle state.

FIG. 14 is a diagram illustrating various aberrations at a wide angle end in a standard state.

FIG. 15 is a diagram illustrating various aberrations in an intermediate focal region in a standard state.

FIG. 16 is a diagram illustrating various aberrations at a telephoto end in a standard state.

FIG. 17 is a diagram illustrating various aberrations at a wide-angle end in a telephoto state.

FIG. 18 is a diagram illustrating various aberrations in an intermediate focal region in a telephoto state.

FIG. 19 is a diagram illustrating various aberrations at a telephoto end in a telephoto state.

FIG. 20 is a diagram illustrating various aberrations in a wide-angle state.

FIG. 21 is a diagram schematically showing a configuration of an imaging device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Zoom lens, 1A ... Zoom lens, 2 ... Main lens system, 2A ... Main lens system, 10 ... Imaging device, GI ... 1st lens group, GII ... 2nd lens group, GIII ... 3rd lens group,
GIV: fourth lens group, GV: fifth lens group (magnification auxiliary lens), GVI: sixth lens group (magnification auxiliary lens)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA03 LA30 MA08 NA15 PA06 PA07 PA20 PB10 PB11 PB12 PB13 QA02 QA07 QA17 QA21 QA25 QA34 QA42 QA45 RA12 RA13 SA23 SA27 SA29 SA32 SA63 SA65 SA72 SA74 SA87 SA89 SB04 SB05 SB14 SB06 SB14 SB06 SB14 SB05 SB27 5C022 AA01 AB21 AC54

Claims (8)

[Claims] 1. A first lens group having a positive refractive power and a fixed position at all times, and a first lens group having a negative refractive power and mainly performing zooming by moving on an optical axis in order from the object side. Two lens groups,
A main lens including a third lens group having a positive refractive power and a fixed position at all times, and a fourth lens group having a positive refractive power and moving on the optical axis to correct and focus on fluctuations in image position. System and has a negative refractive power and is retracted out of the optical path in a standard state, and is inserted so that the optical axis coincides with the image side of the fourth lens group in use, thereby increasing the focal length range of the main lens system. A fifth lens group functioning as a variable power auxiliary lens that shifts to a telephoto side to set a telephoto state, wherein the fifth lens group is a cemented lens of a convex lens and a concave lens in order from the object side. Alternatively, a zoom lens comprising a cemented lens of a concave lens and a convex lens, and satisfying the following conditions. 0.4 <| f5 / f3 | <0.7 1.25 <β5 <2.1 0.1 <n5n−n5p 10 <ν5n−ν5p 0.2 <| r5,3 / f5 | <0.6 F3: focal length of the third lens group, f5: focal length of the fifth lens group, β5: lateral magnification of the fifth lens group, n5n: refractive index at the d-line of the concave lens of the fifth lens group, n5p: fifth Refractive index at d-line of the convex lens of the lens group, ν5n: Abbe number at the d-line of the concave lens of the fifth lens group, ν5p: Abbe number at the d-line of the convex lens of the fifth lens group, r5,3: of the fifth lens group The radius of curvature of the third surface counted from the object side. 2. The first lens group comprises, in order from the object side, a cemented lens of a concave meniscus lens and a convex meniscus lens and a convex meniscus lens, and satisfies the following conditions. Claim 1
A zoom lens according to claim 1. 0.008 <ΔP1,2 1.67 <n1,3 where ΔP1,2 is a value indicating anomalous dispersion of the second lens counted from the object side of the first lens group, and n1,3 is a first lens group. Is the refractive index at the d-line of the third lens counted from the object side. 3. The zoom lens according to claim 1, wherein the F-number at the wide-angle end of the main lens system in a telephoto state is determined by an effective diameter of the fifth lens group. 4. A first position, which is always fixed, in order from the object side.
A lens group, a second lens group that mainly performs zooming by moving on the optical axis, a third lens group whose position is always fixed,
A main lens system composed of a fourth lens group that moves on the optical axis to correct the fluctuation of the image position and performs focusing, and is retracted outside the optical path in a standard state, and is located on the image side of the fourth lens group in use. A fifth lens group which functions as a variable power auxiliary lens which is inserted so that the optical axes coincide with each other and shifts the focal length range of the main lens system to the telephoto side to bring the telephoto state; A zoom lens having a magnification ratio of 2 times or more, wherein the first lens group includes, in order from the object side, a cemented lens of a concave meniscus lens and a convex lens, and a convex meniscus lens, A zoom lens characterized by satisfying each condition. 1.65 <fT / f1 <2.7 0.035 <ΔP1,2-0.003 <ΔP1,3 <0.003 fT: focal length at the telephoto end of the main lens system in the standard state and the telephoto state, f1 : The focal length of the first lens group, ΔP1,2: a value indicating the anomalous dispersion of the second lens counted from the object side of the first lens group, ΔP1,3: 3 counted from the object side of the first lens group The value indicates the anomalous dispersion of the lens. 5. The zoom lens according to claim 4, wherein a thin resin layer is formed on the surface of the first lens group other than the cemented surface of the convex lens so that the surface has a spherical shape or an aspherical shape. . 6. A first lens unit having a positive refractive power and a fixed position at all times, and a first lens unit having a negative refractive power and mainly performing zooming by moving on an optical axis, in order from the object side. Two lens groups,
A main lens including a third lens group having a positive refractive power and a fixed position at all times, and a fourth lens group having a positive refractive power and moving on the optical axis to correct and focus on fluctuations in image position. System and has a negative refractive power and is retracted out of the optical path in a standard state, and is inserted so that the optical axis coincides with the image side of the fourth lens group in use, thereby increasing the focal length range of the main lens system. A fifth lens group functioning as a variable power auxiliary lens that shifts to a telephoto side to set a telephoto state, wherein the zoom lens is retracted to the object side of the first lens group and out of the optical path in a standard state. A sixth lens group having a negative refractive power and functioning as a variable power auxiliary lens is arranged. When the fifth lens group is retracted outside the optical path, the sixth lens group has the same optical axis. As well as the second
A zoom lens wherein the focal length of the entire lens system is changed to a wide-angle state shorter than that at the wide-angle end in a standard state by moving the lens group to a position at the wide-angle end. 7. The zoom lens according to claim 6, wherein the sixth lens group is constituted by a concave single lens, and satisfies the following conditions. 16 <| f6 / fW | <25 0.25 <| r6,2 / f6 | <0.45 46 <ν6 where f6 is the focal length of the sixth lens group, and fW is the wide-angle end of the main lens system in the standard state. Where r6,2 is the radius of curvature of the second surface of the sixth lens group counted from the object side, and ν6 is the Abbe number of the concave single lens constituting the sixth lens group. 8. A first lens unit having a positive refractive power and a fixed position at all times, and a first lens unit having a negative refractive power and performing zooming mainly by moving on an optical axis in order from the object side. Two lens groups,
A main lens including a third lens group having a positive refractive power and a fixed position at all times, and a fourth lens group having a positive refractive power and moving on the optical axis to correct and focus on fluctuations in image position. An imaging apparatus using, as an imaging lens, a zoom lens constituted by a system and a fifth lens group having a negative refractive power and a sixth lens group having a negative refractive power, each functioning as a variable power auxiliary lens. The fifth lens group is retracted outside the optical path in the standard state, and is inserted so that the optical axis coincides with the image side of the fourth lens group in use so that the focal length range of the main lens system is set to the telephoto side. The sixth lens group is retracted outside the optical path in a standard state, and the first lens group is retracted outside the optical path when the fifth lens group is retracted out of the optical path. The optical axis coincides with the object side of the group And the second lens group is moved to the position at the wide-angle end to shift the focal length of the entire lens system to a wide-angle state shorter than that at the wide-angle end in a standard state. Imaging device.