JP5463855B2 - Zoom lens, camera device, and portable information terminal device - Google Patents

Description

  The present invention relates to a zoom lens, a camera device, and a portable information terminal device.

  In recent years, digital cameras have become widespread, and user demands for digital cameras have been diversified. However, high image quality and miniaturization are always desired by users, and zoom lenses used as photographic lenses are also "high performance and small size." "Balancing" is required.

In terms of miniaturization of the zoom lens, it is necessary to shorten the total lens length (distance from the lens surface closest to the object side to the image plane) during use, and each lens group can suppress the total length during storage. It is also important to reduce the thickness of the sheet.
In terms of improving the performance of the zoom lens, it is necessary to have “resolving power over the entire zoom range” corresponding to an image sensor with at least 10 million to 15 million pixels.

  Furthermore, there are many users who desire a wider angle of view of the taking lens, and it is desirable that the half angle of view at the wide angle end of the zoom lens is 38 degrees or more. Half angle of view: 38 degrees corresponds to a focal length in terms of a 35 mm silver salt camera (so-called Leica version) of 28 mm.

  There is a great demand for a high zoom ratio. If the zoom lens has a zoom ratio of about 28 to 200 mm (about 7.1 times) in terms of the focal length in terms of a 35 mm silver salt camera, it can be considered that almost all general photographing can be performed.

  There are many types of zoom lenses for digital cameras, but the first lens group that has a positive focal length in order from the object side to the image side as a type suitable for high zoom ratio, negative focus A second lens group having a distance, a third lens group having a positive focal length, and a fourth lens group having a positive focal length are disposed, and the first lens group and the first lens group are arranged at the time of zooming from the wide angle end to the telephoto end. In some cases, the distance between the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group changes.

  As a zoom lens of this type, there is a zoom lens in which the first lens unit is fixed or reciprocates in a “convex arc shape on the image side” at the time of zooming. If a large amount of movement is to be secured, the diaphragm arranged in the vicinity of the third lens group is “away from the first lens group even at the wide-angle end”, and when the wide-angle / high zoom ratio is achieved, the first lens group becomes very Easy to grow.

  In order to realize a wide-angle, high-magnification, and compact zoom lens with the zoom lens of the above type, the first lens group is moved so that it is positioned closer to the object side at the telephoto end than at the wide-angle end. The type to be performed is preferable. In this way, by making the total lens length at the wide-angle end shorter than that at the telephoto end, it is possible to sufficiently widen the angle while suppressing an increase in the size of the first lens group.

It is known that the use of a lens having anomalous dispersion is effective in correcting chromatic aberration, although chromatic aberration is not likely to occur when the zoom ratio is increased or the focal length is increased.
A zoom lens of the above type that uses a lens having anomalous dispersion has been proposed in Patent Documents 1 to 4 and the like.

  In the zoom lens described in Patent Document 1, the half angle of view at the wide-angle end is 25 degrees, and in the embodiment described in Patent Document 2 in which the positive, negative, positive, and positive four-group configuration is used, the half angle at the wide-angle end is half. The angle of view is about 29 to 32 degrees, and the zoom lenses described in Patent Documents 1 and 2 do not sufficiently meet recent demands in terms of widening the angle.

  The zoom lens disclosed in Patent Document 3 is widened with a half angle of view at the wide-angle end of about 37 degrees. However, the total number of the 14-lens configuration and the number of components is large, and the total length during storage is reduced and the cost is reduced. There are still challenges in terms.

  The zoom lens described in Patent Document 4 achieves a wide angle and high zoom ratio with a relatively simple configuration, but the total length at the telephoto end is slightly long, and there is still no room for improvement in terms of miniaturization.

  The present invention has been made in view of the above-described circumstances, and can achieve a half angle of view at the wide-angle end of 38 degrees or more and a zoom ratio of 6.5 or more with a small number of lenses such as about 10, and is small. Another object of the present invention is to provide a zoom lens capable of realizing a resolving power corresponding to an image sensor with 10 to 15 million pixels.

  The zoom lens according to claim 1, “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, and a third lens having a positive refractive power. A fourth lens group having a positive refractive power, and an aperture stop disposed between the second lens group and the third lens group, and the first lens is used for zooming from the wide-angle end to the telephoto end. The distance between the lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, and the first lens group The third lens group is a “zoom lens that moves so as to be positioned closer to the object side at the telephoto end than at the wide-angle end”, and has the following characteristics.

That is, refractive index: nd, Abbe number: νd, partial dispersion ratio: Pg, F , and wear degree: FA, conditions:
(1) 1.52 <nd <1.62
(2) 65.0 <νd <75.0
(3) 0.015 <Pg, F-(-0.001802 × νd + 0.6483) <0.050
(4) 30 <FA <500
The third lens group has a positive lens made of an optical glass material that satisfies the above.

The partial dispersion ratio: Pg, F is based on the refractive index of the optical glass material for g line, F line, C line: ng, nF, nC.
Pg, F = (ng-nF) / (nF-nC)
It is an amount defined by

That is, in the zoom lens according to claim 1, the third lens group includes a positive lens made of an optical glass material that satisfies the above conditions (1) to (4) .
3. The zoom lens according to claim 2, wherein, 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, and a third lens having a positive refractive power. A group, a fourth lens group having a positive refractive power, a fifth lens group having a positive or negative refractive power, and an aperture stop disposed between the second lens group and the third lens group, During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group and the fourth lens group increase. A zoom lens in which the distance from the lens group is increased and the first lens group and the third lens group move so as to be positioned closer to the object side at the telephoto end than at the wide-angle end. It has a positive lens made of an optical glass material that satisfies the conditions (1) to (4) ”. It is a sign.
That is, the zoom lens according to claim 2 is characterized in that “the fifth lens group having a positive or negative refractive power” is additionally provided on the image side of the fourth lens group in the zoom lens according to claim 1. To do.

The “abrasion degree” will be described later.
The zoom lens according to claim 1 or 2 , wherein the focal length of the positive lens made of an optical glass material satisfying the conditions (1) to (4) in the third lens group: fap, the focal length of the entire system at the wide angle end: fW But the condition:
(5) 1.0 <fap / fW <2.0
Is preferably satisfied ( Claim 3 ).

The zoom lens according to any one of claims 1 to 3 , wherein the third lens group has "at least two positive lenses and one negative lens, and one of the at least two positive lenses is It can be configured to have an “aspherical surface”.

In this case, the positive lens having the aspherical surface can be formed of “optical glass material not satisfying the above conditions (1) to (3)” ( Claim 4 ), or “conditions (1) to (3 It is also possible to form the optical glass material satisfying ( 1 ).
6. The zoom lens according to claim 4 , wherein the third lens group has “at least one negative lens” as described above, but one negative lens is set to “a negative lens having a concave surface having a strong curvature toward the image side”. This is arranged on the “most image side of the third lens group”, and the concave lens having a strong curvature on the image side of the negative lens has a radius of curvature: r3R, and the focal length of the entire system at the wide angle end: fW.
(6) 0.6 <| r3R | / fW <1.3
( 6 ).

The zoom lens according to any one of claims 1 to 6 , wherein the total movement amount of the first lens unit upon zooming from the wide-angle end to the telephoto end is X1, and the focal length of the entire system at the telephoto end is fT. ,conditions:
(7) 0.20 <X1 / fT <0.45
Is preferably satisfied ( claim 7 ).

The zoom lens according to any one of claims 1 to 7 , wherein the total movement amount of the third lens group upon zooming from the wide-angle end to the telephoto end is X3, and the focal length of the entire system at the telephoto end is fT. ,conditions:
(8) 0.15 <X3 / fT <0.40
Is preferably satisfied ( claim 8 ).

The zoom lens according to any one of claims 1 to 8 , wherein the focal length of the second lens group is f2 and the focal length of the third lens group is f3.
(9) 0.50 <| f2 | / f3 <0.85
Is preferably satisfied ( claim 9 ).
The zoom lens according to any one of claims 1 to 9 , wherein the focal length of the first lens group is f1, and the focal length of the entire system at the wide-angle end is fW.
(10) 5.0 <f1 / fW <8.0
Is preferably satisfied ( claim 10 ).

The zoom lens according to claim 11 has, 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, an aperture stop, and a positive refractive power. The third lens group has a fourth lens group having a positive refractive power, and the distance between the first lens group and the second lens group increases upon zooming from the wide-angle end to the telephoto end. The distance between the third lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, and the first lens group and the third lens group are located closer to the object side at the telephoto end than at the wide angle end. The zoom lens that moves as described above is characterized by the following changes.
Refractive index: nd, Abbe number: νd, and refractive index for g-line, F-line, C-line: ng, nF, nC
Pg, F = (ng-nF) / (nF-nC)
Partial dispersion ratio defined by: Pg, F, and wear degree: FA, conditions:
(1) 1.52 <nd <1.62
(2) 65.0 <νd <75.0
(3) 0.015 <Pg, F-(-0.001802 × νd + 0.6483) <0.050
(4) 30 <FA <500
The third lens group has a positive lens made of an optical glass material that satisfies the above.
That is, in the zoom lens according to the eleventh aspect , at least one additional lens group is provided on the image side of the fourth lens group while the four lens group structure of the zoom lens according to the first aspect is made the minimum necessary lens group structure. It can be added.
The camera device of the present invention is a camera device ( claim 12 ) having the above-mentioned “zoom lens according to any one of claims 1 to 11 ” as a photographing optical system ( claim 12 ), and can also be configured as a silver salt camera. Can preferably be configured as a digital camera.

A portable information terminal device according to the present invention includes the zoom lens according to any one of claims 1 to 11 as a photographing optical system of a camera function unit ( claim 13 ). The camera device according to claim 10 can be used as the camera function unit.

Supplement the explanation.
In the “zoom lens configured based on four lens groups of positive, negative, positive, and positive”, the second lens group is generally configured as a so-called variator that bears the main zooming action. In the present invention, “the third lens unit also shares the zooming effect”, and the burden on the second lens unit is reduced. ”.

  When zooming from the wide-angle end to the telephoto end, the height of the light beam passing through the first lens group is lowered at the wide-angle end by “moving the first lens unit largely toward the object side”, and the first lens unit accompanying the widening of the angle. In addition to suppressing an increase in size of one lens unit, a long focal length is achieved by ensuring a large “interval between the first lens unit and the second lens unit” at the telephoto end.

  That is, when changing the magnification from the wide-angle end to the telephoto end, the “interval between the first lens group and the second lens group” is increased, and the “interval between the second lens group and the third lens group” is decreased, so that the second The magnifications (absolute values) of the lens group and the third lens group both increase, and share the zooming action with each other.

As in the zoom lens of the present invention, it is difficult to correct the “secondary spectrum of longitudinal chromatic aberration on the telephoto side” when high zooming is realized and “especially the focal length at the telephoto end is increased”.
Further, if the focal length at the wide-angle end is shortened to make “more wide-angle”, it is difficult to correct “second-order spectrum of lateral chromatic aberration on the wide-angle side”.

  In the zoom lens of the present invention, an anomalous dispersion material (a material having a large anomalous dispersion) is used to correct the longitudinal chromatic aberration on the telephoto side, the lateral chromatic aberration on the wide-angle side and the secondary spectrum thereof. And the optical characteristics are the major features.

  In general, the effect of reducing the “secondary spectrum of axial chromatic aberration” is greatly improved by using special low dispersion glass for a lens group having a high axial ray height.

  Since the third lens group has a higher axial ray height after the first lens group, a special low dispersion glass is used in the third lens group to sufficiently reduce the secondary spectrum of axial chromatic aberration. It becomes possible to do.

  However, since the special low dispersion glass generally has a low refractive index, the “correction ability of monochromatic aberration” tends to decrease. Accordingly, when the monochromatic aberration and chromatic aberration are to be reduced in a well-balanced manner while configuring the third lens group with a small number of lenses, the use of special low dispersion glass does not necessarily give a sufficient effect.

  In the present invention, “at least one positive lens” in the third lens group is composed of an optical glass material having a refractive index, an Abbe number, and an anomalous dispersion within a range satisfying the conditions (1) to (3). Even when the third lens group is as small as about three, it is possible to “reduce the secondary spectrum of chromatic aberration” and to “correct enough monochromatic aberration”.

  When the refractive index: nd of the optical glass material is 1.52 or less, the correction of monochromatic aberration is insufficient, and when the Abbe number: νd is 65.0 or less, the correction of chromatic aberration is insufficient. Condition (3) If the parameter is 0.015 or less, the correction of the secondary spectrum of chromatic aberration is insufficient.

  For all of the conditions (1) to (3), there is no optical glass material that exceeds the upper limit of these conditions, or even if it exists, it becomes very special and expensive, and adoption as a lens material is not realistic.

The degree of wear of the optical glass material that forms the positive lens of the third lens group and satisfies the conditions (1) to (3): Condition (4) that the FA should satisfy will be described.

Abrasion degree: FA is “Measurement area: 9 cm ² of sample is held at a fixed position of 80 mm from the center of a flat plate made of cast iron rotating 60 minutes per minute in a horizontal plane, average particle diameter: 20 μm alumina abrasive grains: 10 g Wrapping solution with 20 ml of water added uniformly for 5 minutes, weight: wear loss when wrapping with a load of 9.807 N: m, standard sample specified by the Japan Optical Glass Industry Association ( Measure the ratio of wear loss: m0 when wrapping BSC7) under the same conditions,
Assuming that the specific gravity of the sample is “d” and the specific gravity of the standard sample is “d0”, the following formula:
FA = {(m / d) / (m0 / d0)} × 100
This is the amount calculated by

  Wear loss: The greater the m, and the smaller the specific gravity: d, the greater the degree of wear.

  In general, many “optical glass materials having relatively low dispersion and anomalous dispersion” have a high degree of wear. In particular, optical glass materials with wear levels exceeding 500 are problematic in that they are difficult to achieve accuracy in the “lens processing process such as polishing, centering, and cleaning”, and are susceptible to scratches, resulting in poor quality and low yield. This will increase costs.

  Forming the “positive lens of the third lens group” with an optical lens material satisfying the conditions (1) to (3) and having a degree of wear of less than 500 is to maintain the high quality of the zoom lens at a low cost. Is very important.

  Even with such an optical glass material, if the degree of wear is less than 30, it is difficult to wear, so that a long time is required for polishing, which reduces the efficiency of lens production and causes an increase in cost.

A condition (5) that at least one of the positive lenses of the third lens group formed of an optical glass material that satisfies the conditions (1) to (4) should preferably be satisfied will be described.

Condition (5) parameter: If fap / fW is greater than 2.0, the refractive power of the lens using the anomalous dispersion material is not sufficient to sufficiently reduce the secondary spectrum, and sufficient chromatic aberration correction cannot be performed. There is.
Conversely, if the parameter: fap / fW is smaller than 1.0, it becomes difficult to balance chromatic aberration correction and spherical aberration correction. Further, since the curvature of each surface of the positive lens is increased, it is disadvantageous in terms of processing accuracy.

  “Aspherical surface for spherical aberration correction” is preferably used at a location close to the aperture stop. On the other hand, the “lens using an anomalous dispersion material” can be effective not only for longitudinal chromatic aberration but also for reducing the secondary spectrum of lateral chromatic aberration by “moving it away from the aperture stop to some extent”.

From this point of view, when the third lens group is composed of “at least two positive lenses and one negative lens” as in claims 4 and 5 , two positive lenses are provided as in claim 4. It is reasonable to designate the lens closest to the aperture stop as an “aspheric lens that does not satisfy the conditions (1) to (3)” and the positive lens far from the aperture stop as a “lens using an anomalous dispersion material”. It is one of the basic composition.
As described above, the third lens group is an important lens group that “shares the zooming function with the second lens group” and also plays a role of image formation. By adopting the above-described configuration, sufficient aberration correction is possible. It becomes.

Further, if the aperture stop disposed on the object side of the third lens group is at some distance from the third lens group at least at the wide-angle end, even when the positive lens closest to the aperture stop is made of an anomalous dispersion material, It is possible to give an effect to the reduction of the secondary spectrum of lateral chromatic aberration as well as axial chromatic aberration.
In addition, since many optical glass materials having low dispersion and anomalous dispersion have a relatively low transition point: Tg and can be molded at a low temperature, they are suitable for “production of an aspheric lens by glass molding technology”.

Therefore, the aspherical lens using the anomalous dispersion material satisfying the conditions (1) to (3) is selected from the two positive lenses of the third lens group as in the fifth aspect. This is one of the rational configurations.
As described above, the third lens group is “an important lens group that plays a role of both zooming and imaging”. However, by adopting the configuration of claim 4 , sufficient aberration correction is possible.

  In addition, even when a lens using an anomalous dispersion material is produced by glass mold technology, “cold working such as polishing” is often required to form a preform as a base material before molding. The point that the degree of wear is important remains the same.

The condition (6) of claim 6 is a condition that enables better aberration correction.
If the parameter of condition (6): | r3R | / fW is smaller than 0.6, the spherical aberration tends to be overcorrected, and if larger than 1.3, the spherical aberration tends to be undercorrected.

  Further, outside the condition (6), it is difficult to balance coma as with spherical aberration, and outward or inward coma tends to occur in the off-axis peripheral part.

Parameter (7) of claim 7 : If X1 / fT is smaller than 0.20, the amount of movement of the first lens unit accompanying zooming is too small, and the “contribution to zooming” of the second lens unit is too small. It becomes smaller and the “burden for zooming” of the third lens group increases, or the refractive power of the first lens group and the second lens group has to be increased. In any case, “deterioration of various aberrations” Invite.

Further, the “lens total length at the wide-angle end” becomes longer, and the height of the light beam passing through the first lens group increases, leading to an increase in size of the first lens group.
On the other hand, if the parameter X1 / fT is larger than 0.45, the movement amount of the first lens unit due to zooming is too large, and the total length at the wide angle end becomes too short, or the total length at the telephoto end becomes too long. . If the total length at the wide-angle end is too short, the movement space of the third lens group is limited and the “contribution to zooming” of the third lens group becomes small, making it difficult to correct the entire aberration.

  If the total length at the telephoto end becomes too long, it will hinder "downsizing in the total length direction", and the radial direction will be enlarged to ensure the amount of peripheral light at the telephoto end, resulting in image performance due to manufacturing errors such as tilting of the lens barrel. It is easy to invite deterioration.

The parameter of condition (7): X1 / fT is more preferably the condition:
(7A) 0.25 <X1 / fT <0.40
Good to be satisfied.

Parameter (8) in claim 8 : When X3 / fT is smaller than 0.15, the amount of movement of the third lens unit accompanying zooming is small, and “the contribution of the third lens unit to zooming is small”. The burden on the second lens group increases, or the refractive power of the third lens group itself must be increased, and in any case, various aberrations are deteriorated.

  Parameter: If X3 / fT is greater than 0.40, the total lens length at the wide-angle end becomes long, and the height of light passing through the first lens group increases, leading to an increase in size of the first lens group.

The parameter: X3 / fT is more preferably the condition:
(8A) 0.20 <X3 / fT <0.35
Good to be satisfied.

If the parameter: | f2 | / f3 of the condition (9) in claim 9 is smaller than 0.50, the refractive power of the second lens group becomes too strong, and if the parameter: | f2 | / f3 is larger than 0.85 The refractive power of the third lens group becomes too strong. Therefore, outside the range of condition (9), “aberration fluctuation during zooming” tends to increase.

The parameter of condition (10) in claim 10 : When f1 / fW is smaller than 5.0, the imaging magnification of the second lens group is “close to the same magnification” and the zooming efficiency is increased. This is advantageous, but each lens of the first lens group requires a large refractive power, and there is a problem that chromatic aberration at the telephoto end tends to deteriorate, and the first lens group becomes thicker.・ It is disadvantageous in increasing the diameter and realizing downsizing especially in the storage state.

Parameter: When f1 / fW is larger than 8.0, the contribution of the second lens group to the zooming becomes small, so that high zooming becomes difficult.
In the zoom lens according to the present invention, an aperture stop is disposed between the second lens group and the third lens group, and the aperture stop can be “moved independently of the adjacent lens group”.
With such a configuration, it is possible to select a more optimal ray path at any position in a large zooming region of 6.5 times or more, and in particular, freedom of correction for coma aberration, curvature of field, and the like. As a result, the off-axis performance can be improved.

  The distance between the aperture stop and the third lens group is preferably “wider at the wide-angle end than at the telephoto end”. When the third lens group in which “the anomalous dispersion material satisfying the conditions (1) to (3)” is used “is away from the aperture stop at the wide-angle end and approaches the aperture stop at the telephoto end”, the anomalous dispersion is obtained. It effectively acts on “correction of the secondary spectrum of lateral chromatic aberration at the wide-angle end” and effectively acts on “correction of the secondary spectrum of axial chromatic aberration at the telephoto end”.

  Accordingly, it becomes possible to correct chromatic aberration more satisfactorily in the entire zoom range, and in addition, “the aperture stop is brought closer to the first lens group at the wide angle end, and the height of the light beam passing through the first lens group is lowered”. As a result, it is possible to achieve further miniaturization of the first lens group.

For the reasons described above, when the distance between the aperture stop and the third lens group is “wider than the telephoto end at the wide angle end”, the axis between the aperture stop at the wide angle end and the most object side surface of the third lens group. Upper distance: dSW is the focal length of the entire system at the telephoto end: fT.
(11) 0.05 <dSW / fT <0.20
Is preferably satisfied.

  Parameter: If dSW / fT is less than 0.05, the height of the light beam passing through the third lens unit at the wide angle end becomes small, making it difficult to effectively reduce the secondary spectrum of lateral chromatic aberration on the wide angle side. Become. Similarly, the “height of the light beam passing through the first lens group” becomes too large at the wide-angle end, leading to an increase in the size of the first lens group.

  Parameter: If dSW / fT is greater than 0.20, the height of light passing through the third lens group at the wide-angle end increases, the image plane falls over, and “barrel distortion” increases. In particular, it becomes difficult to ensure performance in a wide angle range.

  It is desirable that the first lens group has at least one negative lens and at least one positive lens from the object side. More specifically, in order from the object side, a two-lens configuration in which a negative meniscus lens having a convex surface facing the object side and a positive lens having a strong convex surface facing the object side are arranged, or sequentially from the object side, A three-lens configuration in which a negative meniscus lens having a convex surface facing the object side, a positive lens having a strong convex surface facing the object side, and a positive lens having a strong convex surface facing the object side is preferable.

  In order to achieve a high zoom ratio, in particular, “increase the focal length at the telephoto end”, the “combining magnification of the second lens group, the third lens group, and the fourth lens group” at the telephoto end must be increased. Accordingly, “the aberration generated in the first lens group is magnified on the image plane”.

  Therefore, in order to achieve a high zoom ratio, it is necessary to sufficiently reduce the “aberration amount generated in the first lens group”. For this purpose, the first lens group is preferably configured as described above.

  The second lens group includes, in order from the object side, a negative lens having a large curvature surface facing the image side, a positive lens having a large curvature surface facing the image side, and a negative lens having a large curvature surface facing the object side. It is preferable to use a three-sheet configuration.

  When the variable power group having negative refracting power is made up of three lenses, an arrangement of a negative lens, a negative lens, and a positive lens in order from the object side is well known. The above structure of the group is excellent in “correction ability of lateral chromatic aberration accompanying widening of angle”. The second lens and the third lens from the object side may be appropriately joined.

  At this time, it is preferable that each lens of the second lens group satisfies the following conditional expression.

1.75 <N21 <2.10, 25 <ν21 <55
1.75 <N22 <2.10, 15 <ν22 <35
1.75 <N23 <2.10, 25 <ν23 <55
Under these conditions, “N2i, ν2i (i = 1 to 3)” is the refractive index and Abbe number of the “i-th lens counted from the object side” in the second lens group.

By selecting a glass type that satisfies such conditions, it becomes possible to “correctly correct chromatic aberration while keeping monochromatic aberration sufficiently small”.
The third lens group preferably has a three-lens configuration in which a “positive lens, a positive lens, and a negative lens” are arranged in order from the object side, as in the embodiments described later, and the second positive lens from the object side. And the third negative lens may be appropriately joined.

  The fourth lens group in the zoom lens according to the present invention mainly has functions of “securing exit pupil distance (telecentricity)” and “focusing by its movement”. In order to reduce the size of the zoom lens, the fourth lens group should be as simple as possible, and is preferably composed of one positive lens.

  The use of an aspherical surface is indispensable in order to achieve “smaller size” while maintaining good aberration correction. Even in the zoom lens of the present invention, at least the second lens group and the third lens group each have one or more surfaces. It preferably has an aspheric surface.

  In particular, in the second lens group, if both the “most object-side surface and the most image-side surface” are aspherical surfaces, it is highly effective in correcting “distortion and astigmatism that easily increase with widening of the angle”. Can be obtained.

  As an aspheric lens, an optical glass material or an optical plastic material is molded (glass molded aspheric surface, plastic molded aspheric surface), or a thin resin layer is molded on the lens surface of the glass lens, and the surface is aspherical. (Referred to as hybrid aspherical surface, replica aspherical surface, etc.) can be used.

  It may be simple in terms of mechanism that the aperture diameter of the aperture stop is “constant regardless of zooming”. However, by increasing the aperture diameter of the long focal point compared to the short focal point, the F number associated with zooming is increased. It is also possible to reduce the change of.

When it is necessary to reduce the amount of light that reaches the image plane, it is possible to “reduce the aperture”. However, if the amount of light is reduced by “inserting an ND filter” without greatly changing the aperture diameter, it is caused by the diffraction phenomenon. It is preferable because a decrease in resolution can be prevented.
As described above, the zoom lenses according to the first, second, and eleventh aspects have the positive, negative, positive, and positive four-group configuration according to the first aspect, and the positive third lens group includes conditions (1) to (4). The point that a positive lens made of an optical glass material that satisfies the above conditions is included is a common point in technical thought, and this configuration is the basic configuration.
According to a second aspect of the present invention, in the above basic configuration, the fifth lens group is added to the image side of the fourth lens group .
Similarly to the zoom lens according to the first aspect, the zoom lens according to the second aspect preferably satisfies the conditions (5) to (11) described above.
Similarly, it is preferable that the zoom lens according to claim 11 satisfies the above conditions (5) to (11). According to a second aspect of the present invention, a fifth lens group is added to the zoom lens having the above basic configuration.
The zoom lens design condition according to claim 1 which is a basic configuration is slightly relaxed to increase the degree of freedom of design, and the tendency of performance degradation when the first to fourth lens groups are configured under such a relaxed condition, By adding the fifth lens group, it is possible to correct and realize good performance, and for such correction purposes, the refractive power of the fifth lens group may be positive or negative. It is possible.
12. The zoom lens according to claim 11, wherein not only a fifth lens group having a positive or negative refractive power can be added to the image side of the fourth lens group, but also a sixth lens group or the like can be added to the image side. Is leaving. By adding such an additional lens group, the design of the zoom lens can be made easier.

As described above, according to the present invention, a novel zoom lens can be realized.
According to the present invention, as described in the examples below, the above-described configuration has a half field angle at the wide-angle end: a wide field angle of 38 degrees or more, a high zoom ratio of 6.5 times or more, and 10 million to A zoom lens having a resolving power corresponding to an image sensor with 15 million pixels can be realized compactly with as few as 10 lenses.

Further, by satisfying the following conditions (5) , the performance such as chromatic aberration can be improved. Therefore, a camera device / personal digital assistant device with good performance can be realized using the zoom lens as a photographing optical system.

3 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 1. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 2. FIG. 6 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 3. FIG. 7 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 4. FIG. 10 is a cross-sectional view illustrating a configuration of a zoom lens according to Example 5. FIG. FIG. 6 is an aberration curve diagram at the short focal point of the zoom lens according to Example 1; FIG. 6 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 1; FIG. 6 is an aberration curve diagram at the long focal end of the zoom lens of Example 1; FIG. 6 is an aberration curve diagram at the short focal point of the zoom lens according to Example 2; FIG. 6 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 2. FIG. 6 is an aberration curve diagram at the long focal end of the zoom lens of Example 2; FIG. 10 is an aberration curve diagram at the short focal end of the zoom lens according to Example 3; FIG. 6 is an aberration curve diagram at an intermediate focal length of the zoom lens of Example 3; FIG. 10 is an aberration curve diagram at the long focal end of the zoom lens according to Example 3; FIG. 6 is an aberration curve diagram at the short focal point of the zoom lens according to Example 4; FIG. 10 is an aberration curve diagram at an intermediate focal length of the zoom lens according to Example 4; FIG. 10 is an aberration curve diagram at the long focal end of the zoom lens according to Example 4; FIG. 10 is an aberration curve diagram at the short focal end of the zoom lens according to Example 5; FIG. 10 is an aberration curve diagram at an intermediate focal length of the zoom lens according to Example 5; FIG. 10 is an aberration curve diagram at the long focal end of the zoom lens according to Example 5; It is a figure for demonstrating the imaging | photography function part of a portable information terminal device. It is a figure for demonstrating the system of the portable information terminal device of FIG.

Hereinafter, embodiments will be described.
FIG. 1 is a diagram showing an embodiment of a zoom lens.
The zoom lens according to this embodiment relates to a specific example 1 described later.
FIG. 2 is a diagram showing another embodiment of the zoom lens.
The zoom lens according to this embodiment relates to a specific example 2 which will be described later.
FIG. 3 is a diagram showing another embodiment of the zoom lens.
The zoom lens according to this embodiment relates to a specific example 3 which will be described later.
FIG. 4 is a diagram showing still another embodiment of the zoom lens.
The zoom lens according to this embodiment relates to a specific example 4 which will be described later.
FIG. 5 is a diagram showing still another embodiment of the zoom lens.
The zoom lens according to this embodiment relates to a specific example 5 which will be described later.
In order to avoid complications, the same reference numerals are used in FIGS.
The zoom lens shown in FIGS. 1 to 4 includes a first lens group I having a positive refractive power and a second lens group having a negative refractive power in order from the object side (left side of each figure) to the image side. II, a third lens group III having positive refractive power, a fourth lens group IV having positive refractive power, and an aperture stop S are disposed between the second lens group II and the third lens group III. It becomes. That is, the refractive power distribution of the zoom lenses of these embodiments is positive, negative, positive, and positive.
The zoom lens shown in FIG. 5 includes a first lens group I having a positive refractive power, a second lens group II having a negative refractive power, and a positive lens in order from the object side (left side of each figure) to the image side. A third lens group III having a refractive power, a fourth lens group IV having a positive refractive power, a fifth lens group V having a positive refractive power, and a second lens group II and a third lens group III. An aperture stop S is arranged between the two. That is, the zoom lens according to the embodiment of FIG. 5 has positive, negative, positive, positive, and positive power distribution.

When zooming from the wide-angle end (the uppermost figure in each figure) to the telephoto end (the lowermost figure in each figure), the distance between the first lens group I and the second lens group II increases, and the second lens The distance between the group II and the third lens group III is decreased, the distance between the third lens group III and the fourth lens group IV is increased, and the first lens group I and the third lens group III are more than at the wide-angle end. Move to the object side at the telephoto end. The fifth lens group V in the zoom lens of FIG. 5 is configured by a single positive meniscus lens having a convex surface facing the object side, and does not move during zooming.
That is, the fifth lens group V in the embodiment of FIG. 5 is a “fixed group”.

  In each of the embodiments shown in FIGS. 1 to 5, the third lens group III includes two positive lenses (two biconvex lenses on the object side) and one negative lens (lens on the most image side). And the negative lens arranged closest to the image side and the biconvex lens on the object side are cemented, and the negative lens arranged closest to the image side of the third lens group is “a concave surface having a strong curvature toward the image side. It is a biconcave lens.

  Each of the zoom lenses according to these embodiments has a positive lens made of an optical glass material that satisfies the conditions (1) to (3) in the third lens group III.

  1 to 3 (Examples 1 to 3 to be described later), the optical glass material of the biconvex lens closest to the object side (left side) of the third lens group III satisfies the conditions (1) to (3). Fulfill. In this case, the optical glass material of the biconvex lens cemented with the negative lens does not satisfy the conditions (1) to (3).

In the embodiment of FIG. 4 (Example 4 to be described later), the optical glass material of the biconvex lens joined to the negative lens in the third lens group III satisfies the conditions (1) to (3) and is the most object side. The optical glass material of the biconvex lens disposed in the lens does not satisfy the conditions (1) to (3).
In the embodiment of FIG. 5 (Example 5 described later), the optical glass material of the biconvex lens joined to the negative lens in the three lens group III satisfies the conditions (1) to (3). The optical glass material of the biconvex lens arranged on the most object side does not satisfy the conditions (2) and (3).

  Further, the zoom lenses of specific Examples 1 to 5 corresponding to these embodiments all satisfy the conditions (4) to (10) and the condition (11), and the above conditions (7A) and (8A) are satisfied. ) Is also satisfied.

  An embodiment of a “portable information terminal device” will be described with reference to FIGS. 21 and 22.

  The portable information terminal device has a camera device as a “camera function unit”.

FIG. 21 shows the appearance of the camera device (camera function unit of the portable information terminal device), and FIG. 22 shows the system configuration of the portable information terminal device.
As shown in FIG. 22, the portable information terminal device 30 includes a photographing lens 31 and a light receiving element (an electronic imaging element in which 10 million to 15 million pixels are two-dimensionally arranged) 45, and is formed by the photographing lens 31. The “photographing object image” is read by the light receiving element 45.

  As the photographic lens 31, the zoom lens according to any one of claims 1 to 10, more specifically, the zoom lens of Examples 1 to 4 described later is used.

  The output from the light receiving element 45 is processed by the signal processing device 42 under the control of the central processing unit 40, converted into digital information, and the digitized image information is received by the image processing device 41 under the control of the central processing unit 40. After being subjected to predetermined image processing, it is recorded in the semiconductor memory 44.

  The liquid crystal monitor 38 can display an image being image-processed by the image processing device 41 or can display an image recorded in the semiconductor memory 44. The image recorded in the semiconductor memory 44 can be transmitted to the outside using a communication card 43 or the like.

  The image processing apparatus 41 also has a function of performing “electrical shading correction”, “trimming of the image center”, and the like.

  As shown in FIG. 21, when the taking lens 31 is carried, it is in a retracted state as shown in FIG. 21A, and when the user operates the power switch 36 to turn on the power, the mirror 31 as shown in FIG. The torso is paid out.

  At this time, each group of zoom lenses in the lens barrel is “for example, an arrangement at the wide-angle end”, and the arrangement of each group is changed by operating the zoom lever 34, and “zooming to the telephoto end” is performed. It can be carried out. At this time, the viewfinder 33 also zooms in conjunction with the change in the angle of view of the photographic lens 31.

  “Focusing” is performed by half-pressing the shutter button 35.

  Focusing can be performed by moving the second lens group or the fourth lens group, moving the light receiving element 45, or “moving the light receiving element 45 along with the movement of the second lens group or the fourth lens group”.

  When the image recorded in the semiconductor memory 44 is displayed on the liquid crystal monitor 38 or transmitted to the outside using a communication card or the like, the operation button 37 shown in FIG. 17C is used. A semiconductor memory, a communication card, and the like are used by being inserted into dedicated or general-purpose slots 39A and 39B, respectively.

  When the photographing lens 31 is in the retracted state, the lens groups of the zoom lens do not necessarily have to be arranged on the optical axis. For example, the third lens group and / or the fourth lens group are retracted from the optical axis. If the mechanism is housed in parallel with other lens groups, the portable information terminal device can be made thinner.

  In the “portable information terminal apparatus having a camera device as a photographing unit” as described above, the zoom lens of Examples 1 to 5 can be used as the photographing lens 31, and the light receiving element 45 exceeding 10 million pixels. A portable information terminal device with high image quality and a small camera function can be realized.

  Examples of specific zoom lens values will be described below. In all of the examples, the maximum image height is 4.05 mm.

  In each embodiment, a parallel plate (indicated by symbol F in FIGS. 1 to 4) disposed on the image plane side of the fourth lens group is a filter such as an optical low-pass filter or an infrared cut filter, or a CCD sensor. This is assumed to be a parallel flat plate equivalent to a cover glass (seal glass) of a light receiving element.

  In all the embodiments, the lens material is “optical glass material” except that the “positive lens” constituting the fourth lens group IV is an optical plastic.

The meanings of the symbols in the examples are as follows.
f: Focal length of the entire system
F: F number
ω: Half angle of view
R: radius of curvature
D: Face spacing
Nd: Refractive index
νd: Abbe number
K: Aspheric conical constant
A4: Fourth-order aspheric coefficient
A6: 6th-order aspheric coefficient
A8: 8th-order aspheric coefficient
A10: 10th-order aspheric coefficient
A12: 12th-order aspheric coefficient
A14: 14th-order aspheric coefficient
A16: 16th-order aspheric coefficient
A18: 18th-order aspheric coefficient.

  An aspherical surface is well known by using the reciprocal of the paraxial radius of curvature (paraxial curvature) as C, the height from the optical axis as H, the conic constant: K, the aspherical coefficient of construction “A4, A6,. It is expressed by the following formula.

X = CH ² / [1 + √ (1- (1 + K) C ² H ² )]
+ A4 ・ H ⁴ + A6 ・ H ⁶ + A8 ・ H ⁸ + A10 ・ H ¹⁰ + A12 ・ H ¹² + A14 ・ H ¹⁴ + A16 ・ H ¹⁶ + A18 ・ H ¹⁸ .

"Example 1"
f = 5.07 to 34.50, F = 3.48 to 5.65, ω = 39.79 to 6.52
Surface number RD Nd νd Pg, F
01 44.010 1.00 1.92286 18.90 0.6495 OHARA S-NPH2
02 25.696 2.58 1.71300 53.87 0.5459 OHARA S-LAL8
03 158.136 0.10
04 21.124 2.23 1.77250 49.60 0.5520 OHARA S-LAH66
05 60.343 Variable (A)
06 * 48.042 0.74 1.88300 40.76 0.5667 OHARA S-LAH58
07 4.562 2.45
08 46.615 2.12 1.92286 18.90 0.6495 OHARA S-NPH2
09 -10.781 0.64 2.00330 28.27 0.5980 OHARA S-LAH79
10 * -176.830 Variable (B)
11 Aperture variable (C)
12 * 5.844 2.95 1.55332 71.68 0.5402 HOYA M-FCD500
13 * -9.056 0.10
14 7.355 2.10 1.62230 53.17 0.5542 OHARA S-BSM22
15 -12.396 0.60 1.90366 31.32 0.5947 HOYA TAFD25
16 4.446 Variable (D)
17 * 8.757 2.29 1.52470 56.20 Optical plastic
18 106.665 Variable (E)
19 ∞ 0.80 1.51680 64.20 Various filters
20 ∞.

“Aspherical surface” (surface marked with “*” in the above data. The same applies to Examples 2 to 4 below.)
6th page
K = 0.0, A4 = 2.47187 × 10 ^-5 , A6 = -2.33739 × 10 ^-6 , A8 = 1.40335 × 10 ^-7 ,
A10 = -3.70011 × 10 ^-9 , A12 = 3.54383 × 10 ^-12 , A14 = 6.39319 × 10 ^-13
10th page
K = 0.0, A4 = -3.99709 × 10 ^-4 , A6 = -3.19281 × 10 ^-6 , A8 = -1.20904 × 10 ^-7 ,
A10 = -3.19854 × 10 ^-8
12th page
K = 0.0, A4 = -8.15177 × 10 ^-4 , A6 = 1.43767 × 10 ^-5 , A8 = -1.42505 × 10 ^-6 ,
A10 = 9.97953 × 10 ^-8
Side 13
K = 0.0, A4 = 5.34757 × 10 ^-4 , A6 = 2.83041 × 10 ^-5 , A8 = -2.34413 × 10 ^-6 ,
A10 = 1.69514 × 10 ^-7
17th page
K = 0.0, A4 = -1.04517 × 10 ^-4 , A6 = 7.81280 × 10 ^-6 , A8 = -2.51666 × 10 ^-7 ,
A10 = 4.09360 × 10 ^-9 .

"Variable amount"
Short focal end Intermediate focal length Long focal end
f = 5.072 f = 13.168 f = 34.499
A 0.600 8.550 14.656
B 9.480 3.800 0.900
C 4.263 1.650 0.650
D 4.210 6.003 11.719
E 2.445 4.222 3.015.

"Parameter values for conditional expressions"
Pg, F-(-0.001802 × νd + 0.6483) = 0.0211… HOYA M-FCD500
FA = 430 HOYAM-FCD500
fap / fW = 1.36
| r3R | / fW = 0.877
X1 / fT = 0.288
X3 / fT = 0.234
| f2 | / f3 = 0.716
f1 / fW = 6.11
dSW / fT = 0.124.

"Example 2"
f = 5.07 to 34.53, F = 3.45 to 5.61, ω = 39.75 to 6.55
Surface number RD Nd νd Pg, F
01 34.416 1.00 2.00069 25.46 0.6135 HOYA TAFD40
02 19.937 2.91 1.59282 68.63 0.5441 HOYA FCD505
03 130.300 0.10
04 19.487 2.43 1.77250 49.60 0.5520 OHARA S-LAH66
05 67.560 Variable (A)
06 * 49.383 0.74 1.88300 40.76 0.5667 OHARA S-LAH58
07 4.329 2.19
08 35.544 1.99 1.92286 18.90 0.6495 OHARA S-NPH2
09 -11.473 0.64 2.00330 28.27 0.5980 OHARA S-LAH79
10 * -220.632 Variable (B)
11 Aperture variable (C)
12 * 5.883 2.93 1.55332 71.68 0.5402 HOYA M-FCD500
13 * -8.593 0.10
14 8.618 2.20 1.65100 56.16 0.5482 OHARA S-LAL54
15 -9.711 0.60 1.85026 32.27 0.5929 OHARA S-LAH71
16 4.491 Variable (D)
17 * 10.454 2.21 1.52470 56.20 Optical plastic
18 -99.551 Variable (E)
19 ∞ 0.80 1.51680 64.20 Various filters
20 ∞.

"Aspherical surface"
6th page
K = 0.0, A4 = 4.38118 × 10 ^-5 , A6 = -3.28212 × 10 ^-6 , A8 = 1.67801 × 10 ^-7 ,
A10 = -4.32537 × 10 ^-9 , A12 = -1.26659 × 10 ^-11 , A14 = 1.27763 × 10 ^-12
10th page
K = 0.0, A4 = -4.80018 × 10 ^-4 , A6 = -4.53081 × 10 ^-6 , A8 = -2.73503 × 10 ^-7 ,
A10 = -5.07166 × 10 ^-8
12th page
K = 0.0, A4 = -8.76064 × 10 ^-4 , A6 = 1.71719 × 10 ^-5 , A8 = -1.39333 × 10 ^-6 ,
A10 = 9.31505 × 10 ^-8
Side 13
K = 0.0, A4 = 5.89357 × 10 ^-4 , A6 = 3.03606 × 10 ^-5 , A8 = -2.25267 × 10 ^-6 ,
A10 = 1.54591 × 10 ^-7
17th page
K = 0.0, A4 = -5.88625 × 10 ^-5 , A6 = 1.08911 × 10 ^-5 , A8 = -4.32420 × 10 ^-7 ,
A10 = 7.34514 × 10 ^-9 .

"Variable amount"
Short focal end Intermediate focal length Long focal end
f = 5.075 f = 13.180 f = 34.531
A 0.600 8.169 14.520
B 7.927 2.234 0.900
C 4.439 3.062 0.650
D 2.823 4.745 11.720
E 3.435 5.264 3.014.

"Parameter values for conditional expressions"
Pg, F-(-0.001802 × νd + 0.6483) = 0.0211… HOYA M-FCD500
fap / fW = 1.34
FA = 430 HOYAM-FCD500
| r3R | / fW = 0.885
X1 / fT = 0.335
X3 / fT = 0.245
| f2 | / f3 = 0.716
f1 / fW = 6.06
dSW / fT = 0.129.

"Example 3"
f = 5.07 to 34.45, F = 3.44 to 5.57, ω = 39.77 to 6.81
Surface number RD Nd νd Pg, F
01 52.874 1.00 1.92286 18.90 0.6495 OHARA S-NPH2
02 30.779 2.45 1.78800 47.37 0.5559 OHARA S-LAH64
03 566.184 0.10
04 * 14.939 2.58 1.55332 71.68 0.5402 HOYA M-FCD500
05 30.390 Variable (A)
06 * 48.218 0.74 1.88300 40.76 0.5667 OHARA S-LAH58
07 4.324 2.33
08 205.967 2.16 2.00069 25.46 0.6135 HOYA TAFD40
09 -7.694 0.64 1.85135 40.10 0.5694 HOYA M-TAFD305
10 * -521.286 Variable (B)
11 Aperture variable (C)
12 * 6.137 2.80 1.55332 71.68 0.5402 HOYA M-FCD500
13 * -8.456 0.10
14 9.541 2.21 1.61800 63.33 0.5441 OHARA S-PHM52
15 -11.599 0.60 1.85026 32.27 0.5929 OHARA S-LAH71
16 4.921 Variable (D)
17 * 21.300 2.25 1.52470 56.20 Optical plastic
18 -13.467 Variable (E)
19 ∞ 0.80 1.51680 64.20 Various filters
20 ∞.

"Aspherical surface"
4th page
K = 0.0, A4 = -2.61959 × 10 ^-6 , A6 = -4.61000 × 10 ^-8 , A8 = 4.12097 × 10 ^-10 ,
A10 = -2.83406 × 10 ^-12
6th page
K = 0.0, A4 = 4.69989 × 10 ^-5 , A6 = -6.00298 × 10 ^-6 , A8 = 2.85972 × 10 ^-7 ,
A10 = -4.67475 × 10 ^-9 , A12 = -8.20307 × 10 ^-11 , A14 = 2.46554 × 10 ^-12
10th page
K = 0.0, A4 = -5.17867 × 10 ^-4 , A6 = -9.91338 × 10 ^-6 , A8 = -2.02961 × 10 ^-7 ,
A10 = -5.38642 × 10 ^-8
12th page
K = 0.0, A4 = -7.45563 × 10 ^-4 , A6 = 1.45957 × 10 ^-5 , A8 = -1.41743 × 10 ^-6 ,
A10 = 1.11141 × 10 ^-7
Side 13
K = 0.0, A4 = 7.01916 × 10 ^-4 , A6 = 2.59719 × 10 ^-5 , A8 = -2.44987 × 10 ^-6 ,
A10 = 1.76570 × 10 ^-7
17th page
K = 0.0, A4 = -2.49031 × 10 ^-5 , A6 = 6.74925 × 10 ^-6 , A8 = -2.86346 × 10 ^-7 ,
A10 = 4.04476 × 10 ^-9 .

"Variable amount"
Short focal end Intermediate focal length Long focal end
f = 5.074 f = 13.161 f = 34.450
A 0.600 8.718 14.856
B 7.529 1.935 0.900
C 4.880 4.129 0.650
D 2.000 6.189 11.984
E 4.365 4.469 2.532.

"Parameter values for conditional expressions"
Pg, F-(-0.001802 × νd + 0.6483) = 0.0211… HOYA M-FCD500
FA = 430 HOYAM-FCD500
fap / fW = 1.36
| r3R | / fW = 0.970
X1 / fT = 0.335
X3 / fT = 0.231
| f2 | / f3 = 0.713
f1 / fW = 6.26
dSW / fT = 0.142.

Example 4
f = 5.06 to 34.50, F = 3.49 to 5.67, ω = 39.85 to 6.77
Surface number RD Nd νd Pg, F
01 46.479 1.00 1.92286 18.90 0.6495 OHARA S-NPH2
02 28.340 2.56 1.77250 49.60 0.5520 OHARA S-LAH66
03 416.600 0.10
04 * 14.296 2.40 1.55332 71.68 0.5402 HOYA M-FCD500
05 26.318 Variable (A)
06 * 50.551 0.74 1.88300 40.76 0.5667 OHARA S-LAH58
07 4.347 2.39
08 268.383 2.18 2.00069 25.46 0.6135 HOYA TAFD40
09 -7.762 0.64 1.85135 40.10 0.5694 HOYA M-TAFD305
10 * -405.417 Variable (B)
11 Aperture variable (C)
12 * 6.037 2.75 1.51633 64.06 0.5333 OHARA L-BSL7
13 -8.210 0.10
14 7.936 2.36 1.59282 68.63 0.5441 HOYA FCD505
15 -9.478 0.60 1.85026 32.27 0.5929 OHARA S-LAH71
16 4.855 Variable (D)
17 * 21.081 2.00 1.52470 56.20 Optical plastic
18 -13.476 Variable (E)
19 ∞ 0.80 1.51680 64.20 Various filters
20 ∞.

"Aspherical surface"
4th page
K = 0.0, A4 = -2.13930 × 10 ^-6 , A6 = -5.68815 × 10 ^-8 , A8 = 5.09447 × 10 ^-10 ,
A10 = -3.52370 × 10 ^-12
6th page
K = 0.0, A4 = 6.98920 × 10 ^-5 , A6 = -6.51267 × 10 ^-6 , A8 = 3.05288 × 10 ⁻⁷ ,
A10 = -4.97334 × 10 ^-9 , A12 = -7.64920 × 10 ^-11 , A14 = 2.31453 × 10 ^-12
10th page
K = 0.0, A4 = -4.84852 × 10 ^-4 , A6 = -1.06293 × 10 ^-5 , A8 = 1.65811 × 10 ^-8 ,
A10 = -5.72723 × 10 ^-8
12th page
K = 0.0, A4 = -7.11335 × 10 ^-4 , A6 = 1.19186 × 10 ^-5 , A8 = -1.35662 × 10 ^-6 ,
A10 = 1.20507 × 10 ^-7
Side 13
K = 0.0, A4 = 6.51905 × 10 ^-4 , A6 = 2.55654 × 10 ^-5 , A8 = -2.41458 × 10 ^-6 ,
A10 = 1.89127 × 10 ^-7
17th page
K = 0.0, A4 = -9.04702 × 10 ^-5 , A6 = 9.86668 × 10 ^-6 , A8 = -4.20068 × 10 ^-7 ,
A10 = 6.42194 × 10 ^-9 .

"Variable amount"
Short focal end Intermediate focal length Long focal end
f = 5.061 f = 13.144 f = 34.503
A 0.600 8.583 14.642
B 7.867 1.694 0.900
C 4.718 4.584 0.650
D 2.000 6.351 11.947
E 4.180 4.150 2.557.

"Parameter values for conditional expressions"
Pg, F-(-0.001802 × νd + 0.6483) = 0.0195… HOYA FCD505
FA = 460 HOYAM-FCD505
fap / fW = 1.52
| r3R | / fW = 0.959
X1 / fT = 0.328
X3 / fT = 0.241
| f2 | / f3 = 0.718
f1 / fW = 6.26
dSW / fT = 0.137.

"Example 5"
f = 5.07 to 34.46, F = 3.43 to 5.79, ω = 39.82 to 6.53
Surface number RDN _d ν _d P _{g, F}
01 36.861 1.00 1.92286 18.90 0.6495 OHARA S-NPH2
02 24.198 2.90 1.59282 68.63 0.5520 HOYA FCD505
03 370.861 0.10
04 17.021 2.37 1.75500 52.32 0.5402 HOYA TAC6
05 35.390 Variable (A)
06 * 33.358 0.74 1.88300 40.76 0.5667 OHARA S-LAH58
07 4.063 2.16
08 72.493 2.09 1.84666 23.78 0.6135 HOYA FDS90
09 -7.451 0.64 1.82080 42.71 0.5694 HOYA M-TAFD51
10 * -534.330 variable (B)
11 Aperture variable (C)
12 * 6.787 2.76 1.58913 61.15 0.5333 OHARA L-BAL35
13 * -8.678 0.13
14 11.340 2.33 1.59282 68.63 0.5441 HOYA FCD505
15 -7.520 0.60 1.68893 31.16 0.5929 HOYA E-FD8
16 4.761 Variable (D)
17 * 13.573 1.74 1.52470 56.20 Optical plastic
18 153.380 Variable (E)
19 15.998 1.20 1.48749 70.44 HOYA FC5
20 234.342 1.10
21 ∞ 0.80 1.51680 64.20 Various filters
22 ∞

"Aspherical surface"
6th page
K = 0.0, A ₄ = -2.11567 × 10 ^-5 , A ₆ = 1.02684 × 10 ^-7 , A ₈ = -4.62111 × 10 ^-8 ,
A ₁₀ = 7.02968 × 10 ^-10
10th page
K = 0.0, A ₄ = -6.56577 × 10 ^-4 , A ₆ = -6.52956 × 10 ^-6 , A ₈ = -1.05912 × 10 ^-6 ,
A ₁₀ = -5.75774 × 10 ^-8
12th page
K = 0.0, A ₄ = -8.54494 × 10 ^-4 , A ₆ = 5.37510 × 10 ^-6 , A ₈ = -8.26341 × 10 ^-7 ,
A ₁₀ = -5.09750 × 10 ^-8
Side 13
K = 0.0, A ₄ = 3.54458 × 10 ^-4 , A ₆ = 6.38751 × 10 ^-6 , A ₈ = -7.62332 × 10 ^-7 ,
A ₁₀ = -5.58192 × 10 ^-8
17th page
K = 0.0, A ₄ = -3.04703 × 10 ^-5 , A ₆ = 1.04070 × 10 ^-5 , A ₈ = -4.76045 × 10 ^-7 ,
A ₁₀ = 9.37621 × 10 ^-9

"Variable amount"
Short focal end Intermediate focal length Long focal end
f = 5.067 f = 13.151 f = 34.459
A 0.600 7.344 14.239
B 6.716 2.239 0.950
C 4.616 2.573 0.600
D 2.503 4.089 11.904
E 2.666 5.280 1.000

"Parameter values for conditional expressions"
P _{g, F} -(-0.001802 × ν _d + 0.6483) = 0.0195… HOYA FCD505
F _A = 460… HOYA FCD505
f _ap / f _W = 1.58
| r _3R | / f _W = 0.940
X ₁ / f _T = 0.336
X ₃ / f _T = 0.224
| f ₂ | / f ₃ = 0.668
f ₁ / f _W = 5.85
d _SW / f _T = 0.135

6, 7, and 8 show aberration curve diagrams at the short focal end, the intermediate focal length, and the long focal end of the zoom lens of Example 1. FIG.
9, 10, and 11 are aberration curve diagrams of the zoom lens of Example 2 at the short focal end, the intermediate focal length, and the long focal end.
FIGS. 12, 13, and 14 show aberration curves at the short focal end, intermediate focal length, and long focal end of the zoom lens according to the third embodiment.
FIGS. 15, 16, and 17 show aberration curves at the short focal end, intermediate focal length, and long focal end of the zoom lens according to the fourth embodiment.
FIGS. 18, 19, and 20 are aberration curve diagrams of the zoom lens of Example 5 at the short focal end, the intermediate focal length, and the long focal end, respectively.
The broken line in the spherical aberration diagram indicates the “sine condition”. In the figure of astigmatism, the solid line represents “sagittal” and the broken line represents “meridional”.

  In each of the examples, the aberration is sufficiently corrected, and it can be applied to a light receiving element having 10 to 15 million pixels.

I First lens group
II Second lens group
III Third lens group
IV Fourth lens group
S Aperture stop

Japanese Patent Laid-Open No. 08-248317 JP 2001-194590 A JP 2004-333768 A JP 2008-026837 A

Claims (13)

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 first lens group having a positive refractive power. 4 lens groups are arranged, and an aperture stop is disposed between the second lens group and the third lens group. When zooming from the wide angle end to the telephoto end, the first lens group and the second lens group The distance increases, the distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, and the first lens group and the third lens group are at the wide-angle end. In a zoom lens that moves to be closer to the object side at the telephoto end,
Refractive index: nd, Abbe number: νd, and refractive index for g-line, F-line, C-line: ng, nF, nC
Pg, F = (ng-nF) / (nF-nC)
Partial dispersion ratio defined by: Pg, F , and degree of wear: FA, conditions:
(1) 1.52 <nd <1.62
(2) 65.0 <νd <75.0
(3) 0.015 <Pg, F-(-0.001802 × νd + 0.6483) <0.050
(4) 30 <FA <500
A zoom lens, wherein the third lens group has a positive lens made of an optical glass material that satisfies the above. 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 first lens group having a positive refractive power. Four lens groups and a fifth lens group having positive or negative refractive power are arranged, and an aperture stop is arranged between the second lens group and the third lens group, and zooming from the wide-angle end to the telephoto end is performed. At this time, the distance between the first lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the distance between the third lens group and the fourth lens group is increased. In the zoom lens in which the first lens group and the third lens group move so as to be positioned closer to the object side at the telephoto end than at the wide-angle end,
Refractive index: nd, Abbe number: νd, and refractive index for g-line, F-line, C-line: ng, nF, nC
Pg, F = (ng-nF) / (nF-nC)
Partial dispersion ratio defined by: Pg, F , and degree of wear: FA, conditions:
(1) 1.52 <nd <1.62
(2) 65.0 <νd <75.0
(3) 0.015 <Pg, F-(-0.001802 × νd + 0.6483) <0.050
(4) 30 <FA <500
A zoom lens, wherein the third lens group has a positive lens made of an optical glass material that satisfies the above. The zoom lens according to claim 1 or 2,
The focal length of the positive lens made of an optical glass material satisfying the conditions (1) to (4) in the third lens group: fap, the focal length of the entire system at the wide angle end: fW, the conditions:
(5) 1.0 <fap / fW <2.0
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 3,
The third lens group has at least two positive lenses and one negative lens, and one of the at least two positive lenses has an aspheric surface, and an optical glass of a positive lens having the aspheric surface. A zoom lens characterized in that the material does not satisfy the conditions (1) to (3). The zoom lens according to any one of claims 1 to 3,
The third lens group has at least two positive lenses and one negative lens, and one of the at least two positive lenses has an aspheric surface, and constitutes a positive lens having the aspheric surface. A zoom lens characterized in that the optical glass material satisfies the conditions (1) to (3). The zoom lens according to claim 4 or 5,
A negative lens with a concave surface with a strong curvature facing the image side is arranged on the most image side of the third lens group, and the curvature radius of the concave surface with a strong curvature on the image side of the negative lens is r3R, the focal point of the entire system at the wide-angle end. Distance: fW is required:
(6) 0.6 <| r3R | / fW <1.3
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 6,
The total movement amount of the first lens unit during zooming from the wide-angle end to the telephoto end: X1, and the focal length of the entire system at the telephoto end: fT.
(7) 0.20 <X1 / fT <0.45
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 7,
The total movement amount of the third lens unit during zooming from the wide-angle end to the telephoto end: X3, and the focal length of the entire system at the telephoto end: fT.
(8) 0.15 <X3 / fT <0.40
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 8,
The focal length of the second lens group is f2, and the focal length of the third lens group is f3.
(9) 0.50 <| f2 | / f3 <0.85
A zoom lens characterized by satisfying The zoom lens according to any one of claims 1 to 9,
The focal length of the first lens group is f1, and the focal length of the entire system at the wide angle end is fW.
(10) 5.0 <f1 / fW <8.0
A zoom lens characterized by satisfying 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, an aperture stop, a third lens group having a positive refractive power, and a positive refractive power And the distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is increased during zooming from the wide-angle end to the telephoto end. In the zoom lens in which the distance between the third lens group and the fourth lens group decreases, and the first lens group and the third lens group move so that they are located closer to the object side at the telephoto end than at the wide angle end.
Refractive index: nd, Abbe number: νd, and refractive index for g-line, F-line, C-line: ng, nF, nC
P g, F = (ng-nF) / (nF-nC)
Partial dispersion ratio defined by: Pg, F, and wear degree: FA, conditions:
(1) 1.52 <nd <1.62
(2) 65.0 <νd <75.0
(3) 0.015 <Pg, F-(-0.001802 × νd + 0.6483) <0.050
(4) 30 <FA <500
A zoom lens, wherein the third lens group has a positive lens made of an optical glass material that satisfies the above. A camera apparatus comprising the zoom lens according to claim 1 as a photographing optical system. A portable information terminal device comprising the zoom lens according to any one of claims 1 to 11 as a photographing optical system of a camera function unit.

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