CN217082412U - Optical lens with multiple lens combinations - Google Patents

Abstract

The utility model provides a multi-lens combined optical lens, which comprises a rear lens group, a middle lens group and a front lens group which are arranged at intervals; the rear lens group comprises a rear group of plano-convex lenses, the front lens group comprises a front group of concave-convex lenses, and the middle lens group comprises a middle group of concave-plano lenses and a middle group of concave-convex lenses; the rear group of plano-convex lenses, the middle group of concave-plano lenses, the middle group of concave-convex lenses and the front group of concave-convex lenses are all spherical lenses and are arranged in sequence from the object source side to the imaging side along the optical axis; the light passes through the lens to be sequentially subjected to first gathering, first diffusion, second gathering, third diffusion and fourth gathering; the exit angle of the light is small.

Description

Optical lens with multiple lens combinations

Technical Field

The utility model relates to an optical lens field, concretely relates to optical lens of many lens combinations.

Background

The imaging lamp projects light spots on a target surface into various shapes such as a circle, a rectangle and a triangle or projects various required pattern shapes and patterns, and the matched LED light source creates specific and various stage effects and atmospheres, so that the imaging lamp is widely applied to occasions such as stage art sets, photo studios and studios.

The lens used by the high-power LED imaging lamp in the current market is generally divided into two types: one kind of LED light source adopts integrated COBLED light source, and this kind of light source is because the concentration degree is high, and the heat is handled difficultly, and general power does not do much. The other type of light source adopts a distributed LED light source, the distance between chips of the light source is large, and heat treatment is simple, so that the light source can be used for a high-power LED imaging lamp scheme. However, most of the high-power LED imaging lamps in the market adopt a design scheme of an aspheric lens produced by foreign companies, and the processing precision of the aspheric lens in the scheme is highly dependent on, which results in high production cost or poor imaging effect of the lens due to insufficient processing precision.

In Chinese application number 201911221600. X; a patent document published as 2021.06.04 discloses an optical lens, a lens module, and an electronic apparatus; comprises a second mirror group; the second lens group comprises four lenses; a first lens, a second lens, a third lens and a fourth lens which are arranged in order from an object side to an image side along an optical axis; the first lens has negative focal power, the second lens has positive focal power, the third lens has negative focal power, and the fourth lens has positive focal power.

However, the first lens, the second lens, the third lens and the fourth lens are all aspheric lenses, and because the curves of some parts of the surfaces of the aspheric lenses are changed, the curvatures of different positions of the same aspheric lens are not consistent; the aspheric lens has high dependence on processing precision, so that the production cost is high, and the imaging effect of the lens is poor easily due to insufficient processing precision. And it is inconvenient to control the refraction direction of light.

Disclosure of Invention

The utility model provides an optical lens with multiple lens combinations; the use of a spherical lens facilitates control of the direction of refraction of the light. The light passes through the lens to be sequentially subjected to first gathering, first diffusion, second gathering, third diffusion and fourth gathering; the light undergoes six refractions; the emergent angle is small.

In order to achieve the above purpose, the technical scheme of the utility model is that: an optical lens combined by multiple lenses comprises a rear lens group, a middle lens group and a front lens group which are arranged at intervals; the middle lens group is positioned between the rear lens group and the front lens group; the rear lens group comprises a rear group of plano-convex lenses, the front lens group comprises a front group of concave-convex lenses, and the middle lens group comprises a middle group of concave-plano lenses and a middle group of concave-convex lenses; the rear group plano-convex lens, the middle group concave-convex lens and the front group concave-convex lens are all spherical lenses and are sequentially arranged from the object source side to the imaging side along the optical axis.

The side of the rear group of plano-convex lenses close to the object side is a rear group plane, and the side of the rear group of plano-convex lenses close to the image side is a rear group convex surface.

One side of the middle group of the concave flat lens close to the object side is a first middle group of concave surfaces, and one side of the middle group of the concave flat lens close to the image side is a middle group plane; the side of the middle group concave-convex lens close to the object side is a second middle group concave surface, and the side of the middle group concave-convex lens close to the imaging side is a middle group convex surface.

The side of the front group of concave-convex lenses close to the object side is a front group concave surface, and the side of the front group of concave-convex lenses close to the imaging side is a front group convex surface.

The curvature radius of the first middle group of concave surfaces is smaller than that of the rear group of convex surfaces, and the curvature radius of the second middle group of concave surfaces is larger than that of the first middle group of concave surfaces; the radius of curvature of the middle group of convex surfaces is smaller than that of the second middle group of concave surfaces; the curvature radius of the front group of concave surfaces is larger than that of the middle group of convex surfaces, and the curvature radius of the front group of convex surfaces is smaller than that of the front group of concave surfaces; the radius of curvature of the rear set of convex surfaces is less than the radius of curvature of the front set of convex surfaces.

The aperture of the rear group of plano-convex lenses is smaller than that of the front group of concave-convex lenses, and the aperture of the rear group of plano-convex lenses is larger than or equal to that of the middle lens group.

Furthermore, the relative distance between the centers of the rear lens group and the middle lens group is 40-50 mm; the center relative distance between the middle lens group and the front lens group is 12-15 mm; the refractive indexes of the rear group of plano-convex lenses, the middle group of concave-convex lenses and the front group of concave-convex lenses are all 1.517; the refractive index of the middle group of concave-flat lenses was 1.62.

Furthermore, the aperture of the rear group of plano-convex lenses is 80-100 mm; the curvature radius of the convex surface of the rear group is 70-80 mm.

Furthermore, the aperture of the rear group of plano-convex lenses is 90 mm; the radius of curvature of the posterior group convex surface is 79 mm.

Further, the aperture of the front group of concave-convex lenses is 110-130 mm; the curvature radius of the front group of concave surfaces is 500-650 mm; the radius of curvature of the front group of convex surfaces is 70-80 mm.

Further, the aperture of the front group of concave-convex lenses is 120 mm; the curvature radius of the front group of concave surfaces is 620 mm; the radius of curvature of the front set of convex surfaces is 72 mm.

Furthermore, the calibers of the middle group of concave-flat lenses and the middle group of concave-convex lenses are both 70-80 mm; the radius of curvature of the first middle group of concave surfaces is 40-50 mm; the curvature radius of the concave surfaces of the second middle group is 120-140 mm; the curvature radius of the convex surface of the middle group is 40-50 mm.

Furthermore, the aperture of the middle group of concave flat lenses is 70 mm; the radius of curvature of the first set of concavities was 40 mm.

Furthermore, the caliber of the concave-convex lens of the middle group is 70 mm; the radius of curvature of the concave surfaces of the second middle group is 137 mm; the radius of curvature of the convex surface of the middle group is 46 mm.

Further, the center relative distance between the rear lens group and the middle lens group is 47 mm; the center relative distance between the middle lens group and the front lens group is 14 mm.

The spherical lens is used, and the processing is simple; through multi-lens combination; the imaging effect of the emergent light is corrected. The light sequentially passes through the rear group plane, the rear group convex surface, the first middle group concave surface, the middle group plane, the second middle group concave surface, the middle group convex surface, the front group concave surface and the front group convex surface; the light passing through the rear group of convex surfaces is gathered for the first time relative to the incident light of the rear group of convex surfaces; then, the first diffusion occurs through the first middle group of concave surfaces; then, the second diffusion occurs through the second middle group of concave surfaces; then the second gathering occurs after passing through the middle group of convex surfaces; then the third diffusion occurs through the front group of concave surfaces; and then a third bunching occurs across the anterior group convex surface. Namely, the light passes through the lens to be sequentially subjected to first gathering, first diffusion, second gathering, third diffusion and fourth gathering. The light beams are diffused on the middle lens group only twice, and the diffusion times are small; the emergent angle of the light on the convex surface of the front group is small; meanwhile, the light beams are gathered for many times, so that the imaging is clear and the chromatic aberration is small.

The aperture of the rear group of plano-convex lenses is larger than the apertures of the middle group of concave-plano lenses and the middle group of concave-convex lenses; so that the light rays can be gathered on the first middle group of concave surfaces; then diffusing through the second middle group of concave surfaces; gathering the materials through the middle group of convex surfaces, and gathering the materials on the front group of convex surfaces after the front group of concave surfaces are diffused; meanwhile, the curvature radius of the front group of concave surfaces and the front group of convex surfaces is larger than that of the middle group of convex surfaces; the light is less refracted by the front group, so that the emergent angle is large.

Meanwhile, the aperture of the rear group of plano-convex lenses can be equal to the apertures of the middle group of concave-plano lenses and the middle group of concave-convex lenses; and the light rays passing through the rear group of plano-convex lenses can act with all the middle group of concave-plano lenses and the middle group of concave-convex lenses. In the process of generating the optical lens, the angle change of light refraction is large; the light is less refracted when exiting the front set of convex surfaces. Because the curvature radius of the first middle group of concave surfaces is smaller than that of the rear group of convex surfaces, the refraction angle of light during first diffusion is larger than that during first convergence; the curvature radius of the concave surfaces of the second middle group is larger than that of the concave surfaces of the first middle group; the refraction angle of the light during the second diffusion is smaller than that during the first diffusion; the curvature radius of the middle group of convex surfaces is smaller than that of the second middle group of concave surfaces; the refraction angle of the light during the second convergence is larger than that during the second diffusion; because the curvature radius of the front group of concave surfaces is larger than that of the middle group of convex surfaces, the refraction angle of light during the third diffusion is smaller than that during the second convergence; because the curvature radius of the front group convex surface is smaller than that of the front group concave surface, the refraction angle of the light is larger when the light is gathered for the third time than when the light is diffused for the third time.

The radii of curvature of the rear group of convex surfaces, the first middle group of concave surfaces, the second middle group of concave surfaces, the middle group of convex surfaces, the front group of concave surfaces and the front group of convex surfaces are all different; and the difference of the curvature radius between the adjacent curved surfaces is different; when light is refracted on the rear group convex surface, the first middle group concave surface, the second middle group concave surface, the middle group convex surface, the front group concave surface and the front group convex surface, the refraction angles of the light are different; the angle after light refraction does not cancel the angle before light refraction.

Drawings

Fig. 1 is a schematic view of the present invention.

Fig. 2 is a schematic view of an optical path using the first field of view of the present invention.

Fig. 3 is a schematic view of an optical path using the second field of view of the present invention.

Fig. 4 is a schematic diagram of an optical path using the third field of view of the present invention.

Fig. 5 is a schematic diagram of an optical path using the fourth field of view of the present invention.

Fig. 6 is a schematic diagram of an optical path using the fifth field of view of the present invention.

Fig. 7 is a schematic diagram of an optical path using the sixth field of view of the present invention.

Fig. 8 is a diagram of the radius of the circle of dispersion using the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1-8; a multi-lens combined optical lens is used in an LED imaging lamp (not shown in the figure); the light source of the LED imaging lamp is arranged at one end of the optical lens; light emitted by the LED light source is emitted to the optical lens through a light through hole 1 of the LED imaging lamp, and the diameter of the light through hole 1 is 70-80 mm; in this implementation; the diameter of the light through hole 1 of the LED imaging lamp is 77 mm.

The optical lens comprises a rear lens group 2, a middle lens group 3 and a front lens group 4 which are sequentially arranged at intervals from the object side to the imaging side; the center of the light through hole, the center of the rear lens group 2, the center of the middle lens group 3 and the center of the front lens group 4 are positioned on the same straight line, namely an optical axis Q, and the middle lens group 3 is positioned between the rear lens group 2 and the front lens group 4; the center relative distance L1 between the rear lens group 2 and the middle lens group 3 is 40-50 mm; the central relative distance L2 between the middle lens group 3 and the front lens group 4 is 12-15 mm. In the present embodiment; the center relative distance L1 between the rear lens group 2 and the middle lens group 3 is 47 mm; the central relative distance L2 between the middle lens group 3 and the front lens group 4 is 14 mm. The rear lens group 2 comprises a rear group of plano-convex lenses, the front lens group 4 comprises a front group of concave-convex lenses, and the middle lens group 3 comprises a middle group of concave-flat lenses 31 and a middle group of concave-convex lenses 32; the rear group plano-convex lens, the middle group concave-plano lens 31, the middle group meniscus lens 32, and the front group meniscus lens are all spherical lenses, and are arranged in order from the object side to the image side along the optical axis Q.

The aperture of the rear group of plano-convex lenses is 80-100 mm; the side of the rear group of plano-convex lenses close to the object side is a rear group plane 21, and the side of the rear group of plano-convex lenses close to the imaging side is a rear group convex surface 22; the radius of curvature of the posterior group of convex surfaces 22 is 70-80 mm. In this implementation; the aperture of the rear group of plano-convex lenses is 90 mm; the radius of curvature of the posterior group convex surface 22 is 79 mm.

The calibers of the middle group concave-flat lens 31 and the middle group concave-convex lens 32 are both 70-80 mm; the side of the middle group concave-flat lens 31 close to the object side is a first middle group concave surface 311, and the side of the middle group concave-flat lens 31 close to the image side is a middle group plane 312; the side of the middle group meniscus lens 32 close to the object side is a second middle group concave surface 321, and the side of the middle group meniscus lens 32 close to the image side is a middle group convex surface 322; the radius of curvature of the first middle group of concave surfaces 311 is 40-50 mm; the curvature radius of the second middle group of concave surfaces 321 is 120-140 mm; the radius of curvature of the middle set of convex surfaces 322 is 40-50 mm. In the present embodiment, the aperture of each of the middle group meniscus lens 31 and the middle group meniscus lens 32 is 70 mm; the radius of curvature of the first middle group of concave surfaces 311 is 40 mm; the radius of curvature of the second middle group of concave surfaces 321 is 137 mm; the radius of curvature of the middle set of convex surfaces 322 is 46 mm.

The aperture of the front group of concave-convex lenses is 110-130 mm; the side of the front group of concave-convex lenses close to the object side is a front group concave surface 41, and the side of the front group of concave-convex lenses close to the imaging side is a front group convex surface 42; the curvature radius of the front group concave surface 41 is 500-650 mm; the radius of curvature of the front set of convex surfaces 42 is 70-80 mm. In this embodiment, the aperture of the front group meniscus lens is 120 mm; the radius of curvature of the front group of concave surfaces 41 is 620 mm; the radius of curvature of the front set of convex surfaces 42 is 72 mm.

In the present embodiment, the material of the rear group of plano-convex lenses is made of H-K9L optical glass, the refractive index is 1.517, and the abbe number is 64.2; the middle group of concave-flat lenses are made of H-F4 optical glass, the refractive index is 1.62, and the dispersion coefficient is 35.355; the material of the middle group concave-convex lens is H-K9L, the refractive index is 1.517, and the dispersion coefficient is 64.2; the front group of concave-convex lenses is made of H-K9L optical glass, the refractive index is 1.517, and the dispersion coefficient is 64.2.

In another embodiment, the aperture of the posterior group plano-convex lens is 100mm, and the radius of curvature of the posterior group convex surface 22 is 70 mm; the aperture of the middle group concave-flat lens 31 and the aperture of the middle group concave-convex lens 32 are both 80mm, the curvature radius of the first middle group concave surface 311 is 50mm, the curvature radius of the second middle group concave surface 321 is 121mm, and the curvature radius of the middle group convex surface 322 is 41 mm; the aperture of the front group concave-convex lens is 129mm, and the curvature radius of the front group concave surface 41 is 520 mm; the radius of curvature of the front set of convex surfaces 42 is 79 mm.

The spherical lens is used, and the processing is simple; through multi-lens combination; the imaging effect of the emergent light is corrected. The light sequentially passes through the rear group plane 21, the rear group convex surface 22, the first middle group concave surface 311, the middle group plane 312, the second middle group concave surface 321, the middle group convex surface 322, the front group concave surface 41 and the front group convex surface 42; the first gathering of light passing through the rear group of convex surfaces 22 occurs with respect to the incident light rays of the rear group of convex surfaces; then a first diffusion occurs through the first middle set of concavities 311; then a second diffusion occurs through the second middle set of concavities 321; then passes through the middle group convex surface 322 to generate second gathering; a third diffusion then takes place through the front set of concavities 41; a third bunching then occurs across anterior group convexity 42. Namely, the light passes through the lens to be sequentially subjected to first gathering, first diffusion, second gathering, third diffusion and fourth gathering. The light beams are diffused on the middle lens group only twice, and the diffusion times are small; the emergent angle of the light on the convex surface of the front group is small; meanwhile, the light beams are gathered for many times, so that the imaging is clear and the chromatic aberration is small.

The aperture of the rear group of plano-convex lenses is larger than the apertures of the middle group of concave-plano lenses and the middle group of concave-convex lenses; so that the light rays can be gathered on the first middle group of concave surfaces; then diffusing through the second middle group of concave surfaces; after being gathered by the middle group convex surface, the front group concave surface is gathered on the front group convex surface after being diffused; meanwhile, the curvature radius of the front group of concave surfaces and the front group of convex surfaces is larger than that of the middle group of convex surfaces; the light is less refracted by the front group, so that the emergent angle is large.

In the process of generating the optical lens, the angle change of light refraction is large; the light is less refracted when exiting the front set of convex surfaces. Because the curvature radius of the first middle group concave surface 311 is smaller than that of the rear group convex surface 22, the refraction angle of light during first diffusion is larger than that during first convergence; since the radius of curvature of the second middle group concave surface 321 is larger than the radius of curvature of the first middle group concave surface 311; the refraction angle of the light during the second diffusion is smaller than that during the first diffusion; because the radius of curvature of the middle group convex surface 322 is smaller than the radius of curvature of the second middle group concave surface 321; the refraction angle of the light during the second convergence is larger than that during the second diffusion; because the radius of curvature of the front group concave surface 41 is larger than that of the middle group convex surface 322, the refraction angle of light during the third diffusion is smaller than that during the second convergence; since the radius of curvature of front group convex surface 42 is smaller than the radius of curvature of front group concave surface 41, the refraction angle of light at the third convergence is larger than that at the third diffusion.

The radii of curvature of the posterior group convex surface 22, the first medial group concave surface 311, the second medial group concave surface 321, the medial group convex surface 322, the anterior group concave surface 41, and the anterior group convex surface 42 are all different; and the difference of the curvature radius between the adjacent curved surfaces is different; when light is refracted on the rear group convex surface 22, the first middle group concave surface 311, the second middle group concave surface 321, the middle group convex surface 322, the front group concave surface 41 and the front group convex surface, the refraction angles of the light are different; the angle after light refraction does not cancel the angle before light refraction.

Referring to fig. 2-8, a first circle of confusion a1 is a projection of a first field of view a; the second circle of confusion b1 is the projection of the second field of view b; a third circle of confusion c1 is a projection of a third field of view c; the fourth circle of confusion d1 is the projection of the fourth field of view d; a fifth circle of confusion e1 is the projection of the fifth field of view e; a sixth circle of confusion f1 is the projection of the sixth field of view f; the first circle of confusion a1, the second circle of confusion b1, the third circle of confusion c1, the fourth circle of confusion d1, the fifth circle of confusion e1 and the sixth circle of confusion f1 are all composed of blue light, red light and green light.

In this implementation, the central axis of the light of the first field of view a coincides with the optical axis; the second field of view b is located above the first field of view a, the angle between the central axis of the light of the second field of view b and the optical axis being 6.5 °, and the distance between the central axis of the light of the second field of view b and the optical axis being 19.553 mm.

In this embodiment, the third field of view c is located above the second field of view b, the angle between the central axis of the light of the third field of view c and the optical axis is 9.19 °, and the distance between the central axis of the light of the third field of view c and the optical axis is 27.607 mm.

In this embodiment, the fourth field of view d is located above the third field of view c, the angle between the central axis of the light of the fourth field of view d and the optical axis is 10.4 °, and the distance between the central axis of the light of the fourth field of view d and the optical axis is 31.164 mm.

In this embodiment, the fifth field of view e is located above the fourth field of view d, the angle between the central axis of the light of the fifth field of view e and the optical axis is 11.7 °, and the distance between the central axis of the light of the fifth field of view e and the optical axis is 34.898 mm.

In this embodiment, the sixth field of view f is located above the fifth field of view e, the angle between the central axis of the light of the sixth field of view f and the optical axis is 13 °, and the distance between the central axis of the light of the sixth field of view f and the optical axis is 38.466 mm.

A first circle of confusion a1, a second circle of confusion b1, a third circle of confusion c1, a fourth circle of confusion d1, a fifth circle of confusion e1, and a sixth circle of confusion f 1; the radiuses of the six groups of dispersion circles are small enough, so that the imaging effect is good.

The emergent angle of light passing through the lens is 23-28 degrees; in this implementation; the outgoing angle of the light after passing through the lens is 26 degrees.

Claims (10)

1. A multi-lens combined optical lens, characterized in that: comprises a rear lens group, a middle lens group and a front lens group which are arranged at intervals; the middle lens group is positioned between the rear lens group and the front lens group; the rear lens group comprises a rear group of plano-convex lenses, the front lens group comprises a front group of concave-convex lenses, and the middle lens group comprises a middle group of concave-plano lenses and a middle group of concave-convex lenses; the rear group of plano-convex lenses, the middle group of concave-plano lenses, the middle group of concave-convex lenses and the front group of concave-convex lenses are all spherical lenses and are arranged in sequence from the object source side to the imaging side along the optical axis;

one side of the rear group of plano-convex lenses close to the object side is a rear group plane, and one side of the rear group of plano-convex lenses close to the imaging side is a rear group convex surface;

one side of the middle group of the concave flat lens close to the object side is a first middle group of concave surfaces, and one side of the middle group of the concave flat lens close to the imaging side is a middle group plane; the side, close to the object side, of the middle group of concave-convex lenses is a second middle group of concave surfaces, and the side, close to the image side, of the middle group of concave-convex lenses is a middle group of convex surfaces;

one side of the front group of concave-convex lenses, which is close to the object side, is a front group of concave surfaces, and one side of the front group of concave-convex lenses, which is close to the image side, is a front group of convex surfaces;

the curvature radius of the first middle group of concave surfaces is smaller than that of the rear group of convex surfaces, and the curvature radius of the second middle group of concave surfaces is larger than that of the first middle group of concave surfaces; the radius of curvature of the middle group of convex surfaces is smaller than that of the second middle group of concave surfaces; the curvature radius of the front group of concave surfaces is larger than that of the middle group of convex surfaces, and the curvature radius of the front group of convex surfaces is smaller than that of the front group of concave surfaces; the curvature radius of the rear group of convex surfaces is smaller than that of the front group of convex surfaces;

the aperture of the rear group of plano-convex lenses is smaller than that of the front group of concave-convex lenses, and the aperture of the rear group of plano-convex lenses is larger than or equal to that of the middle lens group.

2. A multi-lens combined optical lens according to claim 1, characterized in that: the center relative distance between the rear lens group and the middle lens group is 40-50 mm; the center relative distance between the middle lens group and the front lens group is 12-15 mm; the refractive indexes of the rear group of plano-convex lenses, the middle group of concave-convex lenses and the front group of concave-convex lenses are all 1.517; the refractive index of the middle group of concave-flat lenses was 1.62.

3. A multi-lens combined optical lens according to claim 1, characterized in that: the aperture of the rear group of plano-convex lenses is 80-100 mm; the curvature radius of the convex surface of the rear group is 70-80 mm.

4. A multi-lens combined optical lens according to claim 3, characterized in that: the aperture of the rear group of plano-convex lenses is 90 mm; the radius of curvature of the posterior group convex surface is 79 mm.

5. A multi-lens combined optical lens according to claim 1, characterized in that: the aperture of the front group of concave-convex lenses is 110-130 mm; the curvature radius of the front group of concave surfaces is 500-650 mm; the radius of curvature of the front group of convex surfaces is 70-80 mm.

6. The multi-lens combined optical lens according to claim 5, wherein: the aperture of the front group of concave-convex lenses is 120 mm; the curvature radius of the front group of concave surfaces is 620 mm; the radius of curvature of the front set of convex surfaces is 72 mm.

7. A multi-lens combined optical lens according to claim 1, characterized in that: the aperture of the middle group of concave-flat lenses and the aperture of the middle group of concave-convex lenses are both 70-80 mm; the radius of curvature of the first group of concavities is 40-50 mm; the curvature radius of the concave surfaces of the second middle group is 120-140 mm; the curvature radius of the convex surface of the middle group is 40-50 mm.

8. A multi-lens combined optical lens according to claim 7, characterized in that: the aperture of the middle group of concave-flat lenses is 70 mm; the radius of curvature of the first set of concavities was 40 mm.

9. A multi-lens combined optical lens according to claim 7, characterized in that: the aperture of the middle group of concave-convex lenses is 70 mm; the radius of curvature of the concave surfaces of the second middle group is 137 mm; the radius of curvature of the convex surface of the middle group is 46 mm.

10. A multi-lens combined optical lens according to claim 2, characterized in that: the center relative distance between the rear lens group and the middle lens group is 47 mm; the center relative distance between the middle lens group and the front lens group is 14 mm.

Images