CN101211003A - zoom lens - Google Patents

Abstract

The present invention relates to a zoom lens including: a negative first lens group G1 , a positive second lens group G2 and a positive third lens group G3 arranged in sequence from the object side to the imaging side. When the focal length of the zoom lens changes from the wide-angle end to the far end, the second lens group G2 moves toward the object side, and at the same time, the first lens group G1 first moves toward the imaging side, and then moves toward the object side, so that the first The distance between the second lens group G1 and G2 becomes smaller, and the third lens group G3 moves when focusing.

Description

zoom lens

technical field

The present invention relates to a zoom lens, especially a miniaturized zoom lens with high image resolution, which can be used in a digital or non-digital Real Image imaging device of a camera.

Background technique

Figure 1 shows the imaging principle diagram of the camera device. When the imaging surface D moves in the horizontal direction, the angle of view A (size 2w) and focal length C will change, and distant objects will become clearer on the imaging surface D through the lens B, making people feel like objects is progressing. There are two ways to change the viewing angle A: one is to change the focal length of the lens, which is commonly referred to as optical zooming (Optical Zooming), which changes the focal length of the lens by changing the relative positions of the lenses in the zoom lens; the other is to change the focal length of the lens. The first is to change the size of the imaging surface, that is, to change the length of the diagonal of the imaging surface. This process is also called digital zooming (Digital Zooming).

The principle of optical zoom is to change the position of the focal point by moving the lens inside the lens B, change the length of the focal length C of the lens, and change the size of the field of view (Field of View, FOV) A of the lens B, so as to realize the enlargement and reduction of the image. When changing the position of the focal point, the focal length C also changes. For example, if the focal point is moved to the opposite direction of the imaging surface D, the focal length C will become longer, and the viewing angle A will also become smaller. In this way, the scene within the viewing angle range will become larger on the imaging surface D. The digital zoom is to use the image processor to separately enlarge the image information obtained by the photosensitive unit in a certain area of the photosensitive component. During digital zooming, the projected image size of the subject through the lens B on the photosensitive component (imaging surface D) does not change, but the internal software of the camera intercepts the pixels passing through the central part of the photosensitive component D, and Use the built-in software to zoom in and interpolate, so as to achieve the effect of zooming in on the image.

There are many types of camera lenses, and commonly used camera lenses include Petzval lenses, Three-lens Type lenses and Wide-angle lenses, etc. Among them, Petzval lenses are composed of two positive focal length lens groups separated from each other. Composed, which is characterized by a large aperture (Aperture) and a small viewing angle A. A typical three-piece objective lens consists of three single lenses with "Positive, Negative, and Positive" refractive indices (RefractivePower), and its viewing angle A is larger than that of the Petzval lens, while the The aperture (Aperture) is smaller. The angle of view A of the wide-angle lens exceeds 60°, and most of them adopt a symmetrical structure. The aperture (Aperture Stop) is located in the center of the lens group, and the lenses are symmetrically arranged relative to the aperture.

A three-group optical zoom lens is often used as a camera lens. The advantage is that the three-group zoom lens has better image resolution and is easy to achieve a compact design. The known three-group optical zoom lens includes a negative first group lens group, a positive second group lens group, and a negative third group lens group. When the zoom lens changes from a short focal length to a long focal length, since the aperture (Aperture Stop) is attached to the second group of the zoom system (Magnification Change), it will move along with the second group to the object side (Object Side) .

U.S. Patent No. 7,072,121 discloses such an optical zoom lens, which includes a positive first lens group, a negative second lens group and a positive third lens group, wherein the first, second and third lens groups are from The object side (Object Side) is arranged in sequence toward the image side (an Image Side), and the second lens group can move along the optical axis (Optical Axis) to change its magnification (Magnification). The zoom lens satisfies 3.7<L _T /F _W <5.4, where L _T is from the object-side surface (Object-Side Plane) of the first lens group to the imaging plane (Image Plane) at the wide-angle end (Wide-AngleEnd) The distance (Distance) between them on the optical axis, and F _W is the total focal length (Overall Focal Length) of the zoom lens at the wide-angle end. The image-side surface (Image-Side Plane) of the first lens group is a concave surface (Concave), the second lens group is a biconvex lens (Double Convex), and the object-side surface (Object-Side Plane) of the third lens group is Concave.

In the prior art, there are also negative, positive, and positive three-group optical zoom lenses. The second group lens group contains three lenses at most, and the first surface is aspherical, but it is only suitable for smaller-sized photosensitive components. , or the zoom ratio is less than three times, and the image resolution is acceptable. If it is used for a photosensitive component with a larger size, the image resolution cannot meet the requirement due to the larger imaging surface. Therefore, the existing negative, positive, and positive three-group optical zoom lenses usually perform poorly in close-range photography, cannot be used for photography with an object distance less than 60 mm, and require a large space.

US Patent No. 7,075,734 discloses a negative, positive, and positive three-group optical zoom lens system, which can provide a zoom ratio of about 3 times. From the object side to the image side, a first lens group, a second lens group and a third lens group are arranged in sequence. When the zoom lens moves (Zoom) from the wide-angle end (Wide-Angle End) to the far end (Telephoto End), the first and second lens groups move while the third lens group is fixed, so that the distance between the first and second lens groups The distance between the lens groups changes, while the distance between the second and third lens groups increases. The second lens group is composed of four or less than four lenses, and a diffractive optical surface (Diffractive Optical Surface) is formed on one lens surface thereof, but the diffractive optical surface is not arranged on the lens surface closest to the object side thereof, and Satisfy 0.2<C/f _W <2.0, wherein C is the effective diameter of the diffractive surface (Effective Diameter), and f _W is the focal length (Focal Length) of the zoom lens system at the wide-angle end. The diffractive surface is designed to reduce its chromatic aberration (Chromatic Aberration), and can also reduce the ghost (Flare) phenomenon of the diffractive optical component.

However, the preparation of the diffractive surface is not only complicated, but also expensive, thus increasing the manufacturing cost of the entire zoom lens system, and also adversely affecting the improvement of the yield of finished products. More importantly, this zoom lens system cannot overcome the above-mentioned shortcomings of the prior art, that is, it is not suitable for use in larger-sized photosensitive components, so it is not suitable for close-up photography, and cannot be used for photography where the object distance is less than 60mm. At the same time, the space required is relatively large.

Therefore, it is necessary to design a new type of three-group optical zoom lens to meet the requirements of miniaturization and higher image resolution at the same time, and can also use larger-sized photosensitive components, so it can meet the needs of high pixels, miniaturization, and close-up Distance photography and other needs.

Contents of the invention

The object of the present invention is to overcome the deficiencies of the prior art above, and to provide a miniaturized three-fold zoom lens, which can be used in digital cameras or non-digital imaging devices. The aspherical surface can meet the requirements of high image resolution, and can be used for larger-sized photosensitive components, and can also be used for close-up photography where the object distance is less than 60mm.

In order to achieve the above purpose, the zoom lens of the present invention includes a negative first lens group G1, a positive second lens group G2 and a positive third lens group G3 arranged in sequence from the object side to the imaging side. When the focal length of the zoom lens changes from the wide-angle end to the far end, the second lens group G2 will move toward the object side, and at the same time, the first lens group G1 will first move toward the imaging side, and then move toward the object side, making the second lens group G1 move toward the object side. The distance between the first and second lens groups G1 and G2 becomes smaller, and the third lens group G3 moves when focusing.

The first lens group G1 includes negative and positive lenses L1 and L2 that are cemented together, wherein the lens L1 is a convex-concave lens, and the lens L2 is a convex-concave lens with a positive refractive index. The first lens group G1 includes five surfaces in total: S1, S2, S3, S4 and S5, wherein the convex surface S1 faces the object side, the concave surface S2 uses a resin compound lens, the surface S3 is aspherical, the convex surface S4 faces the object side, and The concave surface S5 faces the imaging side I.

The focal length f _G1 of the first lens group G1 and the full length L _W of the zoom lens at the wide-angle end satisfy the conditional formula:

$\mathrm{<span\; class="notranslate">\; 0.36</span>}<span\; class="notranslate">\; \&le;</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.44</span>}$

The second lens group G2 is a variable power system, including four lenses, which are arranged in sequence from the object side to the imaging side: a biconvex resin compound lens L3, a group of spherical cemented lenses joined by a biconvex lens L4 and a biconcave lens L5, Lump-concave resin compound lens L6 with convex surface facing the object side. The aperture (Aperture Stop) is set at the front of the second lens group G2 on the side closest to the object.

The diaphragm has one surface S6; the second lens group G2 includes 9 surfaces, respectively S7, S8, S9, S10, S11, S12, S13, S14 and S15. Among them, the surface S7 closest to the object side O is an aspherical surface; the surface S15 is closest to the imaging side I and is an aspherical surface.

The focal length f _L6 of the lens L6 and the focal length f _G2 of the second lens group G2 satisfy the conditional formula:

$\mathrm{<span\; class="notranslate">\; 2.10</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; 6</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 3.20</span>}$

The refractive index N6 and the dispersion coefficient V6 of the lens L6 satisfy the conditional formula 1.65≤6≤1.80, 20≤V6≤35.

The total length D _G2 of the second lens group G2 from the diaphragm closest to the object side to the last surface S15 closest to the imaging side, and the full length L _W of the zoom lens at the wide-angle end satisfy the conditional formula:

$\mathrm{<span\; class="notranslate">\; 0.15</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.23</span>}$

When the zoom lens zooms from a short focal length to a long focal length, the maximum movement amount MTG2 of the second lens group G2 and the focal length fT of the zoom lens at the far end satisfy the conditional formula:

$\mathrm{<span\; class="notranslate">\; 0.53</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; MT</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; \&le;0.66</span>$

The minimum distance D12 between the surface S5 of the first lens group G1 closest to the imaging side and the surface _S7 of the second lens group G2 closest to the object side and the full length L _W of the zoom lens at the wide-angle end satisfy the conditional formula:

$\mathrm{<span\; class="notranslate">\; 0.03</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.09</span>}$

The third lens group G3 is used for focusing, including a biconvex resin composite lens L7, which includes three surfaces S16, S17 and S18, wherein at least the surface S18 is an aspheric surface.

When the zoom lens is focused for close-up photography, the third lens group G3 moves toward the object side, approaching the second lens group G2, thereby reducing the distance between the second and third lens groups G2, G3.

The maximum movement amount FM _G3 of the third lens group G3 when focusing and the total length L _W of the zoom lens at the wide-angle end satisfy the conditional formula:

$\frac{{\mathrm{<span\; class="notranslate">\; FM</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.11</span>}$

The focal length f _G3 of the third lens group G3 satisfies the conditional formula:

$\mathrm{<span\; class="notranslate">\; 0.11</span>}<span\; class="notranslate">\; \&le;</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; FM</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.24</span>}<span\; class="notranslate">\; .</span>$

The mathematical formulas of the aspherical surfaces S3, S7, S15 and S18 of the zoom lens of the present invention are as follows:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="4"\; label="h"\; filenames="A20061006365100315.png"\; state="\{\{state\}\}">h</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="10"\; label="h"\; filenames="A20061006365100274.png,A20061006365100275.png"\; state="\{\{state\}\}">h</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 14</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 14</span>}}$

And C=1/R.

Among them, D is the distance from the most convex point of the zoom lens along the optical axis on the height H; C is the reciprocal of the curved surface radius R; R is the reference radius of the most convex curved surface of the lens; H is the vertical height of the incident light parallel to the optical axis ; K is the taper constant; E ₄ , E ₆ , E ₈ , E ₁₀ , E ₁₂ and E ₁₄ are the second, fourth, sixth, eighth, tenth, twelfth and fourteenth order non- spherical coefficient.

In addition, the lens L1 of the first lens group G1 can be changed to a glass molded lens; the lenses L3 and L6 of the second lens group G2 can be respectively or both changed to a glass molded lens; the lens L7 of the third lens group G3 can also be changed to a glass molded lens. Molded lenses or switch to plastic lenses.

The zoom lens of the present invention is composed of negative, positive and positive first, second and third lens groups G1, G2 and G3. When zooming from the wide-angle end to the far end, the second lens group G2 moves toward the first lens group G1, and the shutter and diaphragm are placed in front of the second lens group G2 and move with it. , while focusing is achieved by the third lens group.

In order to achieve miniaturization and higher image resolution, the present invention adopts a negative, positive, and positive zoom lens. At the same time, in the second lens group, a structure of 4 lenses and 2 aspherical surfaces is used to achieve high Image resolution, miniaturization, and close-up photography are required.

Description of drawings

FIG. 1 is a schematic diagram of the imaging principle of an imaging device in the prior art.

Fig. 2 is a schematic structural diagram of the zoom lens of the present invention.

3A to 3C are schematic diagrams of astigmatism when the zoom lens is located at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the first embodiment of the present invention.

4A to 4C are schematic diagrams of distortion and aberration of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the first embodiment of the present invention.

5A to 5C are schematic diagrams of spherical aberration of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the first embodiment of the present invention.

6A to 6C are schematic diagrams of chromatic aberration of magnification at the wide-angle end, intermediate-angle end, and telephoto end of the zoom lens according to the first embodiment of the present invention.

7A to 7C are schematic diagrams of coma aberration when the zoom lens is located at the wide-angle end, the middle-angle end and the telephoto end respectively in the first embodiment of the present invention.

8A to 8C are schematic diagrams of astigmatic aberrations of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end respectively in the second embodiment of the present invention.

9A to 9C are schematic diagrams of distortion and aberrations of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the second embodiment of the present invention.

10A to 10C are schematic diagrams of spherical aberration of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end respectively in the second embodiment of the present invention.

11A to 11C are schematic diagrams of chromatic aberration of magnification at the wide-angle end, intermediate-angle end, and telephoto end of the zoom lens in the second embodiment of the present invention, respectively.

12A to 12C are schematic diagrams of coma aberration when the zoom lens is located at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the second embodiment of the present invention.

13A to 13C are schematic diagrams of astigmatic aberrations of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end respectively in the third embodiment of the present invention.

14A to 14C are diagrams showing distortion and aberrations of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end respectively in the third embodiment of the present invention.

15A to 15C are schematic diagrams of spherical aberration of the zoom lens at the wide-angle end, intermediate-angle end, and telephoto end respectively in the third embodiment of the present invention.

16A to 16C are schematic diagrams of chromatic aberration of magnification at the wide-angle end, middle-angle end, and telephoto end of the zoom lens in the third embodiment of the present invention.

17A to 17C are schematic diagrams of coma aberration when the zoom lens is located at the wide-angle end, intermediate-angle end, and telephoto end, respectively, in the third embodiment of the present invention.

Detailed ways

Now, the zoom lens of the present invention will be further described in detail in conjunction with the accompanying drawings.

Referring to Fig. 2, the zoom lens of the present invention includes the first lens group G1 and the second lens group G2 which are negative, positive and positive in sequence from the object side (Object Side, O) to the imaging side (Image Side, I) and the third lens group G3.

The first lens group G1 includes negative and positive lenses L1 and L2 that are cemented together, where lens L1 is a convex-concave lens (Convex-Concave Lens), and lens L2 is a convex-concave lens with positive curvature ratio (Positive Curvature Ratio). . The first lens group G1 includes five surfaces in total: S1, S2, S3, S4 and S5, among which, the convex surface S1 faces the object side O, and a resin compound lens is used on the concave surface S2; the surface S3 is aspherical; and the convex surface S4 faces Object side O; and concave surface S5 towards imaging side I.

The conditional expression of the focal length f _G1 of the first lens group G1 and the full length L _W of the lens at the wide-angle end is:

$\mathrm{<span\; class="notranslate">\; 0.36</span>}<span\; class="notranslate">\; \&le;</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.44</span>}$

The second lens group G2 is a zoom system (System of Magnification Change), including four lenses in total, from the object side O to the imaging side I: a double-convex (Double-Convex) resin composite lens L3, composed of A double-convex lens L4 and a double-concave (Double-Concave) lens L5 are bonded to form a set of spherical cemented (Cemented) lenses, and a convex-concave resin compounded (Resin Compounded) lens L6 with the convex surface facing the object side O. The diaphragm (Diaphragm) ST or the aperture stop (Aperture Stop) is arranged in front of the frontmost surface S6 of the second lens group G2 closest to the object side O.

The stop ST has a surface S6; the second lens group G2 includes 9 surfaces, respectively S7, S8, S9, S10, S11, S12, S13, S14 and S15. Among them, the surface S7 closest to the object side O is an aspherical surface; the surface S15 is closest to the imaging side I and is an aspherical surface.

The conditional expression of the focal length f _L6 of the lens L6 and the focal length f _G2 of the second lens group G2 is:

$\mathrm{<span\; class="notranslate">\; 2.10</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 6</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 3.20</span>}$

In addition, the conditional formulas of the glass material refractive index N6 and the dispersion coefficient (DispersionParameter, or Abbe Number) V6 of the resin composite lens L6 are 1.65≤N6≤1.80, 20≤V6≤35.

The focal length f _G2 of the second lens group G2, the total length of the second lens group G2 from the stop ST closest to the object side O to the last surface S15 closest to the imaging side I is D _G2 , and the full length L _W at the wide-angle end The conditional expression for is:

$\mathrm{<span\; class="notranslate">\; 0.15</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.23</span>}$

When the zoom lens 1 of the present invention is zooming from the short focal length (Short Focal Length) to the long focal length (Long Focal Length), the conditions for the maximum moving amount MT _G2 of the second lens group G2 and the far end focal length f _T The formula is:

$\mathrm{<span\; class="notranslate">\; 0.53</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; MT</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.66</span>}$

The minimum distance D 12 between the last surface S5 of the first lens group G1 closest to the imaging side I and the first surface S7 of the second lens group G2 of the zoom system (Magnification Change) closest to the object side O is the smallest distance D ₁₂ . The conditional expression of the full length L _W of the zoom lens 1 at the wide-angle end is:

$\mathrm{<span\; class="notranslate">\; 0.03</span>}<span\; class="notranslate">\; \&le;</span>\frac{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.09</span>}$

The third lens group G3 is composed of a biconvex resin composite lens L7. The lens L7 includes three surfaces S16, S17 and S18, wherein the surface S18 is aspherical. The third lens group G3 is used for focusing. When focusing in close-range photography, the third lens group G3 moves toward the object side O, approaching the second lens group G2, so that the distance between the second and third lens groups G2, G3 decreases. The conditional expression of the maximum moving amount FM _G3 of the third lens group G3 during focusing and the full length L _W of the zoom lens 1 of the present invention at the wide-angle end is:

$\frac{{\mathrm{<span\; class="notranslate">\; FM</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; W</span>}}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.11</span>}$

And the conditional expression of the maximum moving amount FM _G3 and the focal length f _G3 of the third lens group G3 is:

$\mathrm{<span\; class="notranslate">\; 0.11</span>}<span\; class="notranslate">\; \&le;</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; FM</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; G</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0.24</span>}$

Therefore, under this condition, when shooting at close range, the images formed by different object distances can be adjusted on the imaging surface SI, thereby maintaining the excellent imaging quality of the zoom lens 1 of the present invention, and at the same time improving the structure It is also easy to realize miniaturization.

In addition, since the second lens group G2 is a zoom system, aberrations can be corrected by using the front and rear aspheric surfaces S7 and S15. Therefore, when the zoom lens 1 of the present invention changes from a short focal length position to a long focal length position, it has good imaging quality; and when shooting at close range, it can reduce the deterioration of aberrations and maintain excellent imaging quality.

The third lens group G3 of the present invention is mainly used for focusing, so that images formed by objects at different object distances can be adjusted to the imaging surface SI. However, the zooming action of the zoom lens 1 of the present invention from the short focal length position to the long focal length position only requires the first lens group G1 and the second lens group G2 to perform the zooming action from the short focal length to the long focal length, and the third lens group G3 requires no action.

The mathematical formulas of the aspheric surfaces S3, S7, S15 and S18 of the present invention are as follows:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="4"\; label="h"\; filenames="A20061006365100315.png"\; state="\{\{state\}\}">h</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 8</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="10"\; label="h"\; filenames="A20061006365100274.png,A20061006365100275.png"\; state="\{\{state\}\}">h</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 14</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 14</span>}}$

where C=1/R.

Among them, D is the distance from the most convex point of the lens along the optical axis on the height H; C is the reciprocal of the curved surface radius R; R is the reference radius of the most convex curved surface of the lens; H is the vertical height of the incident light parallel to the optical axis; K is the taper constant; E ₄ , E ₆ , E ₈ , E ₁₀ , E ₁₂ and E ₁₄ are the aspheric surfaces of the second, fourth, sixth, eighth, tenth, twelfth and fourteenth orders respectively coefficient.

In the first lens group G1, the first resin composite lens L1 can be replaced with a glass molded lens.

In the second lens group G2, the two resin composite lenses L3 and L6 can respectively or both be replaced with glass molded lenses.

In the third lens group G3, the resin composite lens L7 can be replaced with a glass molded lens or a plastic lens.

To sum up, the zoom lens of the present invention includes three groups of lens groups: negative, positive, and positive in the direction from the object side O to the imaging side I. When the focus distance changes from the wide-angle end (Wide-angle End) to the telephoto end (Telephoto End), the second lens group G2 moves to the object side O direction, and at the same time the first lens group G1 also first moves to the imaging side I direction, Then move to the object side O direction, so that the interval between the first lens group G1 and the second lens group G2 becomes smaller, the diaphragm ST and the shutter are arranged in front of the second lens group G2, and are connected with the second lens group G2 move together. The third lens group G3 only moves when focusing.

The zoom lens of the present invention will be further described in detail with three specific embodiments below:

First embodiment:

Please also refer to FIGS. 3A to 3C , FIGS. 4A to 4C , FIGS. 5A to 5C , FIGS. 6A to 6C , FIGS. 7A to 7C , Table 1, Table 2 and Table 3. Among them, Figs. 3A to 3C show the non-point images of the zoom lens of the present invention respectively located at the wide-angle end (Wide-angle End), the middle-angle end (Medium-angle End) and the far-end (Telephoto End) in the first embodiment Astigmatism; Figures 4A to 4C show the corresponding distortion aberration (Distortion); 5A to 5C show the corresponding spherical aberration (Spherical Aberration); Figures 6A to 6C show the corresponding chromatic aberration of magnification (Chromatic Aberration); and Figures 7A to 7C show the corresponding coma aberration (ComaAberration).

Among them, 2w represents the viewing angle, M represents the meridional plane (Meridional Plane), S represents the sagittal plane (Sagittal Plane), g represents the g line, d represents the d line, and Y represents the chromatic difference of magnification (Chromatic Difference of Magnification).

Table 1 shows the construction data table of the zoom lens of the present invention. Among them, Fno represents the f-number (f-number), and its values at the wide-angle end W and the long-range T are 2.9 and 4.9, respectively. And, f _G1 /L _W =0.4, f _L6 /f _G2 =2.6, N6 =1.74, V6 =30.1, D _G2 /L _W =0.2, MT _G2 /f _T =0.58, D ₁₂ /L _W =0.07, FM _G3 /L _W =0.1, FM _G3 /f _G3 =0.18.

Table 1: Fno2.9～4.9

Table II:

No. K E ₄ E ₆ E _{8 E10} E ₁₂ E ₁₄ 3 -0.880141 6.295435E-5 5391418E-6 -5.009847E-7 2.526534E-8 -6.66860E-10 6.776790E-12 7 0 -2.197872E-4 -1212085E-6 -1.464298E-7 2.280597E-9 0 0 15 0 2.522440E-4 3.616741E-6 -7.959675E-7 6.168328E-8 0 0 18 0 -1.236107E-5 -5.799973E-6 1.996146E-7 -2.496980E-9 0 0

Table 2 shows the relevant parameter table of the four aspherical surfaces S3, S7, S15 and S18 of the zoom lens of the present invention in the first embodiment. Among them, K is the taper constant; E ₄ , E ₆ , E ₈ , E ₁₀ , E ₁₂ and E ₁₄ are the second, fourth, sixth, eighth, tenth, twelfth and fourteenth order respectively Aspheric coefficients.

Table three:

D1 D2 W(f=7.54) 19.077911 5.3329430 M(f=1.98) 6.7435350 11.524372 T(f=3.0) 2.3789230 17.691800

Table 3 shows that in the first embodiment, the zoom lens of the present invention is respectively located at the wide-angle end (Wide-angle End, W), the middle angle end (Medium-angle End, M) and the far end (Telephoto End, T). The distance between the first lens group G1 and the second lens group G3, and the distance between the first lens group G1 and the second lens group G2. Among them, D1 represents the distance along the optical axis from the surface S5 of the first lens group G1 closest to the imaging side I to the surface S16 of the third lens group G3 closest to the object side O; D2 represents the distance from the first lens group G1 The distance between the surface S5 of G1 closest to the imaging side I and the surface S7 of the second lens group G2 closest to the object side O; (Medium-angle End, M) and the focal length at the far end (Telephoto End, T).

Second embodiment:

Please also refer to FIGS. 8A to 8C , FIGS. 9A to 9C , FIGS. 10A to 10C , FIGS. 11A to 11C , FIGS. 12A to 12C , Table 4, Table 5 and Table 6. 8A to 8C show that the zoom lens of the present invention is located at the wide-angle end (Wide-angleEnd, W), the middle-angle end (Medium-angle End, M) and the telephoto end (Telephoto End, T) respectively in the second embodiment. ) of astigmatism (Astigmatism); Figures 9A to 9C show the corresponding distortion aberration (Distortion); Figures 10A to 10C show the corresponding spherical aberration (Spherical Aberration); Figures 11A to 11C show the corresponding The magnification chromatic aberration (ChromaticAberration); and Figures 12A to 12C show the corresponding coma aberration (ComaAberration).

Table 4: Fno2.8～4.9

Table five:

No. K E ₄ E ₆ E _{8 E10} E ₁₂ E ₁₄ 2 -0.723885 6.4931864E-5 4.0945774E-6 -2.989721E-7 1.3656167E-8 -3.295231E-10 3. 2073987E-12 6 0 -1.784709E-4 -9.150737E-7 -1.189172E-7 1.7494424E-9 0 0 12 0 2.0927394E-4 1.2052842E-5 -1.653320E-6 1.4070851E-7 0 0 14 0 -3.150509E-6 -6.912289E-6 2.825945E-7 -4.364480E-9 0 0

Table six:

D1 D2 W(f=7.52) 20.277911 5.3329430 M(f=14.39) 6.7435350 11.524372 T(f=21.43) 2.2789230 17.841800

Table 4 shows that in the second embodiment, the structural parameter (Construction Data) table of the zoom lens of the present invention, wherein, Fno represents the f number (f-number), and its value at the wide-angle end W and the long-range T is respectively 2.8 and 4.9, and f _G1 /L _W = 0.4, f _L6 /f _G2 = 3.1, N6 = 1.69, V6 = 31.1, D _G2 /L _W = 0.18, MT _G2 /f _T = 0.63, D ₁₂ /L _W = 0.05 , FM _G3 /L _W =0.1, FM _G3 /f _G3 =0.18.

In the second embodiment, the relevant parameters of the aspheric surfaces S3, S7, S15, and S18 are shown in Table 5. Table 6 shows that in the present embodiment, the zoom lens of the present invention is respectively located at the wide-angle end (Wide-angle End, W), the middle angle end (Medium-angle End, M) and the far end (Telephoto End, T). The distance D1 between the first lens group G1 and the third lens group G3, and the distance D2 between the first lens group G1 and the second lens group G2.

Third embodiment:

Please also refer to Figures 13A to 13C, Figures 14A to 14C, Figures 15A to 15C, Figures 16A to 16C, Figures 17A to 17C, Table 7, Table 8 and Table 9. Among them, Figures 13A to 13C show the astigmatism (Astigmatism) of the zoom lens of the present invention respectively located at the wide-angle end W, the middle angle end M, and the far end T in the third embodiment; Figures 14A to 14C show the corresponding The distortion aberration (Distortion); Figure 15A to 15C shows the corresponding spherical aberration (Spherical Aberration); Figure 16A to 16C shows the corresponding magnification chromatic aberration (Chromatic Aberration); and Figures 17A to 17C show It is the corresponding coma aberration (ComaAberration).

Table 7: Fno2.8～4.8

Table Eight:

No. K E ₄ E ₆ E _{8 E10} E ₁₂ E ₁₄ 3 -0.725628 6.3579801E-5 4.2978347E-6 -3.089668E-7 1.3626687E-8 -3.2601012E-10 3.200318E-12 7 0 -2.130411E-4 -2.813394E-6 6.7795436E-8 -7.201768E-9 0 0 15 0 2.0677819E-4 2.055404E-5 -3.144532E-6 2333727E-7 0 0 18 0 -1.14539E-5 -7.474764E-6 3.201780E-7 -5.081182E-9 0 0

Table nine:

D1 D2 W(f=7.52) 19.277911 5.3329430 M(f=14.29) 6.9435350 11.524372 T(f=21.62) 2.0789230 17.841800

Table 7 shows that in the third embodiment, the structure parameter (Construction Data) table of the zoom lens of the present invention, wherein, Fno represents the f number (f-number), and its value at the wide-angle end W and the far end T is 2.8 respectively and 4.8, and, f _G1 /L _W = 0.4, f _L6 /f _G2 = 3.1, N6 = 1.69, V6 = 31.1, D _G2 /L W = 0.18, MT _G2 / _{f T =} 0.59, D ₁₂ /L _W =0.07, FM _G3 /L _W =0.09, FM _G3 /f _G3 =0.17.

In the third embodiment, the relevant parameters of the aspheric surfaces S3, S7, S15, and S18 are shown in Table 8. Table 9 shows the distance D1 between the first lens group G1 and the third lens group G3, and the first The distance D2 between the lens group G1 and the second lens group G2.

Table ten:

project L _W D _G2 MT _G2 FM _{G3 f} f _G1 f _{G2 f} f _L6 N6 V6 D ₁₂ Example 1 46.5 9.54 12.4 4.6 21.2 -18.5 13.3 25.6 34.5 1.74 30.1 3.6 Example 2 46.5 8.34 14.3 4.5 22.6 -18.4 13.2 25.6 40.9 1.69 31.1 2.3 Example 3 46.5 8.54 12.7 4.4 21.6 -18.6 13.3 26.0 41.5 1.69 31.1 3.1

Table 10 shows the focal length f _G1 of the zoom lens of the present invention, the full length L _W of the zoom lens of the present invention at the wide-angle end, the focal length f _L6 of the L6 lens, and the second lens in the first, second and third embodiments, respectively. The focal length f _G2 of the group G2, the glass material refractive index N6 and the dispersion coefficient V6 of the resin compound lens L6, the focal length f _G2 of the second lens group G2, the distance from the stop ST closest to the object side O to the second lens group G2 The total length D _G2 of the surface S15 closest to the imaging side I, the maximum movement amount MT _G2 of the second lens group G2 when zooming from the short focal length to the long focal length, and the zoom lens of the present invention at the far end focal length f _T , the first The minimum distance _D12 between the surface S5 of the lens group G1 closest to the imaging side and the surface S7 of the second lens group G2 closest to the object side and the value of the maximum movement amount FM _G3 of the third lens group G3 during focusing.

The invention can replace the glass molded lens with 3 spherical glass lenses and 4 resin composite lenses, thus reducing the production cost. The present invention adopts the zoom lens structure of negative, positive and positive, and the second group lens group G2 uses 4 lenses with 2 aspheric structures, so it can meet the needs of high image resolution, miniaturization, and close-range photography. .

Claims (15)

1. a zoom lens includes in regular turn from object side toward the imaging side direction: the first negative lens set G1, the second positive lens set G2 and positive prismatic glasses group G3; It is characterized in that: when zoom lens is done the focal length variation by wide-angle side is extremely long-range, the second lens set G2 moves to the object side direction, the first lens set G1 moves and then moves to the object side direction to the imaging side direction earlier simultaneously, interval between the first and second lens set G1, the G2 is diminished, and prismatic glasses group G3 moves when focusing.

2. zoom lens according to claim 1 is characterized in that: the first lens set G1 includes negative, positive two pieces of eyeglass L1 and the L2 that is bonded together, and wherein eyeglass L1 is a meniscus, and eyeglass L2 is the meniscus of positive tortuosity ratio; The first lens set G1 includes five surface: S1, S2, S3, S4 and S5, and wherein, convex surface S1 is towards object side, and uses the resin complex optics in concave surface S2; Face S3 is an aspheric surface; And convex surface S4 is towards object side; And concave surface S5 is towards imaging side I.

3. as the zoom lens as described in the claim 2, it is characterized in that: the focal distance f of the first lens set G1 _G1With the total length L of zoom lens in wide-angle side _WFormula satisfies condition:

$0.36\&le;\left|\frac{f_{G1}}{L_W}\right|\&le;0.44.$

4. as the zoom lens as described in the claim 3, it is characterized in that: the second lens set G2 for becoming doubly is, comprise four pieces of eyeglasses, be arranged as in regular turn by object side to imaging side: biconvex resin complex optics L3, one of engage the group sphere with biconcave lens L5 by biconvex lens L4 and engage eyeglass, with the convex-concave resin complex optics L6 of convex surface towards object side.

5. as the zoom lens as described in the claim 4, it is characterized in that: diaphragm be located at the second lens set G2 near the foremost of object side.

6. as the zoom lens as described in the claim 5, it is characterized in that: diaphragm has a surperficial S6; The second lens set G2 comprises 9 surfaces, respectively S7, S8, S9, S10, S11, S12, S13, S14 and S15.Wherein, be aspheric surface near the face S7 of object side O; Face S15 is near imaging side I and be aspheric surface.

7. as the zoom lens as described in the claim 6, it is characterized in that: the focal distance f of eyeglass L6 _L6Focal distance f with the second lens set G2 _G2Formula satisfies condition:

$2.10\&le;\left|\frac{f_{L6}}{f_{G2}}\right|\&le;3.20.$

8. as the zoom lens as described in the claim 7, it is characterized in that: the refractive index N6 of eyeglass L6 and abbe number V6 formula 1.65≤N6≤1.80,20≤V6≤35 that satisfy condition.

9. as the zoom lens as described in the claim 8, it is characterized in that: the second lens set G2 near the diaphragm of object side near the length overall D between the last surperficial S15 of imaging side _G2, with the total length L of zoom lens when the wide-angle side _WFormula satisfies condition:

$0.15\&le;\left|\frac{D_{G2}}{L_W}\right|\&le;0.23.$

10. as the zoom lens as described in the claim 9, it is characterized in that: when zoom lens is done the zoom action by short focal length to long-focus, the maximum amount of movement MT of the second lens set G2 _G2Be visible focal distance f when long-range of zoom lens _TFormula satisfies condition:

$0.53\&le;\left|\frac{{\mathrm{MT}}_{G2}}{f_T}\right|\&le;0.66.$

11. the zoom lens as described in the claim 10 is characterized in that: the first lens set G1 near the surperficial S5 of imaging side and the second lens set G2 near interval D minimum between the surperficial S7 of object side ₁₂With the total length L of zoom lens when the wide-angle side _WFormula satisfies condition:

$0.03\&le;\left|\frac{D_{12}}{L_W}\right|\&le;0.09.$

12. as the zoom lens as described in the claim 11, it is characterized in that: prismatic glasses group G3 does focusing and uses, and comprises a biconvex resin complex optics L7, and it comprises S16, S17 and three faces of S18, and wherein face S18 is an aspheric surface at least.

13. as the zoom lens as described in the claim 12, it is characterized in that: zoom lens is when focusing for closely making a video recording, prismatic glasses group G3 moves toward the object side aspect, near the second lens set G2, thereby make second and prismatic glasses group G2, G3 between the interval reduce.

14. as the zoom lens as described in the claim 13, it is characterized in that: prismatic glasses group G3 is maximum amount of movement FM when focusing _G3With the total length L of zoom lens when the wide-angle side _WFormula satisfies condition:

$\left|\frac{{\mathrm{FM}}_{G3}}{L_W}\right|\&le;0.11.$

And with the focal distance f of prismatic glasses group G3 _G3Formula satisfies condition:

$0.11\&le;\left|\frac{{\mathrm{FM}}_{G3}}{f_{G3}}\right|\&le;0.24.$

15. as the zoom lens as described in the claim 14, it is characterized in that: among the first lens set G1, eyeglass L1 can use the glass moulding eyeglass instead; Among the second lens set G2, eyeglass L3, L6 can be respectively or are all used the glass moulding eyeglass instead; Among the prismatic glasses group G3, eyeglass L7 can use the glass moulding eyeglass instead or use glass lens instead.

Images