KR950007865B1 - Zoom lens for a color video camera - Google Patents

Abstract

The color video camera zoom lens is capable of high magnification, and changes at much magnification rate. The light-weight large-caliber zoom lens is able to take a picture on a dark object. The large-caliber, light zoom lens enables a dark object to be taken on a film. The aberration correction status has a zoom rate of 8 times in camera lens lightness of F1.4 ˜ F1.8 is good.

Description

Zoom lens for color video camera

1 is a block diagram of a zoom lens according to the present invention.

2 is a diagram showing aberration diagrams in each zoom step with respect to the first embodiment.

3 shows aberration diagrams in each zoom step with respect to the second embodiment.

* Explanation of symbols for main parts of the drawings

1: object 2: imaging plane

3: focus part 4: bowel movement part

5: compensation unit 6: imaging unit

7: flat plate 8: all phase open

9: Post imaging focus part 3 10: Stop surface

11: concave lens variable part (4) 12, 13: convex lens

14, 15: concave lens compensator (5) 16: convex lens

17: concave lens before image (8) 18, 18 ', 19': convex lens after image (9)

19: concave lens 20: convex lens

21 convex lens 22 concave lens

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens of a camera. In particular, the present invention relates to a zoom lens having a high magnification change in photographing magnification, and that can be photographed even with a relatively dark object. The present invention relates to a zoom lens for a color video camera having a good aberration correction with a zoom ratio of 1.4 to F / 1.8 of 8 times.

ZOOM LENS is a combination of several convex and concave lenses to reduce or enlarge an image while changing a short or long focal length without changing a camera position.

Since the zoom lens has a larger variation range, the change in the size of the image to be taken varies. Therefore, in order to expand the range of the changed image and the expression of the image, high magnification of the zoom lens is required. To be as large as possible is required.

However, for the high magnification of the zoom lens, the entire zoom lens becomes longer and heavier. In particular, the zoom lens for color video cameras to prevent color bleeding requires a telecentric optical system in which the main light is incident perpendicularly to the upper surface of the zoom lens. This results in the opposite of lightweighting and compacting in pursuit of ease of portability and ease of operation.

Accordingly, the present invention provides a large-diameter zoom lens that can at least have a lens and has good aberration correction, light weight, and improves operability, and is capable of photographing dark objects, and is configured to be close to a telecentric optical system suitable for a color video camera. The improvement is also intended.

In order to achieve this object, in the present invention, the focus portion of (+) power that focuses an object precisely, the variation portion of (-) power that changes the magnification of an image, and the store compensation function according to the variation (- ) Compensation part of power and image forming part of (+) power that forms an image on the upper surface, focus part consists of concave and convex junction lens and convex single lens from object side, and convex part is concave It consists of a single lens of and three lenses of concave and convex, and the compensation portion is composed of a concave single lens. In addition, the imaging section is composed of an image forming front part and an image forming part after the imaging part, so that the axial aberration correction is performed before the imaging part and the axial aberration correction is performed after the imaging part. With the concave and convex lens of the lens and the stop surface inside the image forming part, the whole lens lens system is short in size due to the telecentric close configuration, which makes it possible to achieve compact size and light weight. The brightness of the camera lens is 8 times the zoom ratio of F / 1.4 to F1.8, which prevents color bleeding on the imaging surface.

EMBODIMENT OF THE INVENTION Hereinafter, the structure, operation | movement, and effect of this invention are explained in full detail with reference to the figure which actualized this invention.

The invention consists of a focusing part 3, a shifting part 4, a compensating part 5, an imaging part 6, and a parallel plane plate 7, in turn, from an object 10 to an imaging surface 2. The combination of the lenses, the imaging unit 6 is divided into the imaging front 8 and the imaging rear 9, the imaging front 8 is a zoom lens provided with a stop surface 10 for limiting the brightness of the optical system.

Here, the focusing portion 3 is composed of a convex lens 13 which is a single lens and a joint lens in which the concave lens 11 and the convex lens 12 are joined, and the shift part 4 is a concave lens 14 which is a single lens. ) And the concave lens 15 and the convex lens 16 which are the bonded lenses, and the compensator 5 is composed of the concave lens 17 which is a single lens. In addition, the imaging front part 8 of the imaging part 6 is a convex lens 18 which is a single lens in front of the stop surface 10 and two convex lenses 18 'and 19' and one concave behind the stop surface 10. It consists of a lens 19, the image forming rear portion 9 is composed of three pieces of convex lens 20, convex lens 21 and concave lens 22, reference numeral 7 denotes an optical low pass filter (OPTICAL LOW PASS FILTER) It is a parallel plane plate assuming). This entire lens system is configured to be close to TELECENTRIC in order to prevent color bleeding on the imaging surface.

The above-described zoom lens has the curvature radius Ri (i = 1,2… n) and the spacing Di (i = 1,2… n) of Example 1 on each surface, and the right medium refractive index INDEX of the surface. And dispersion (ν).

Example 1

TABLE 1

In particular, the variable spacing (D ₅ , D ₁₀ , D ₁₂ ) between the zooming lenses, that is, A, B, and C of Example 1 has the values shown in Table 1 below at the wide-angle, intermediate, and telephoto stages. .

TABLE 2

As a numerical value satisfying the above-described Example 1 and Table 1, the lens system focal length f is 8.70 to 66.24 mm, the optical system brightness F / # is 1.4 to 1.8, the angle of view 2w is 49.38 to 6.61 (deg), The rear focal length bf1 from the lens last surface to the image surface is 11.52 mm, and the total length from the lens first surface to the image surface is 107.72 mm. In addition, the second embodiment has a radius of curvature Ri and a spacing Di as shown in the following table, and has a refractive index Index and a dispersion ν when the medium on the right side of the surface is not air.

Example 2

TABLE 3

Here, the variable intervals D ₅ , D ₁₀ , and D ₁₂ of the zoom step, that is, A, B, and C of Example 2 are shown in Table 2 below.

TABLE 4

As a numerical value satisfying the above-described Example 2 and Table 2, the lens system focal length f is 8.70 to 66.24 mm, the optical system brightness F / # is 1.4 to 1.8, the angle of view 2w is 49.38 to 6.61 (deg), The rear focal length bf1 is 11.65 mm and the total length is 107.65 mm.

According to the above configuration, when the camera with the zoom lens starts shooting, the focus unit 3 moves back and forth toward the object 1 to fix the final store, and the zoom step 4 is performed in the zoom unit 4 (WIDE). ) Phase, MIDDLE stage, and telephoto stage [TELE stage] by varying the variable interval (D ₅ , D ₁₀ , D ₁₂ ) and the image is enlarged or reduced.

The image of which the position of the final shop is changed according to the adjustment of the shifting part 4 is the zoom step (from the wide angle step to the telephoto step) in which the concave lens 17 of the compensator 5 changes the intervals D ₁₀ and D ₁₂ . By correcting the shop movement according to the fixed position of the final store.

The stop surface 10 restricts the brightness of the optical system, the axial aberration correction is performed at the image forming unit 8, and the axial aberration correction is performed at the image forming unit 9 to form an image through the parallel plane plate 7. In addition, the image from the focusing portion 3 is adjusted in magnification from the variable displacement unit 4, the shop change caused by the movement of the variable displacement unit 4 is compensated by the compensation unit 5, the plane through the image forming unit 6 Light is incident on the image forming surface 2 via the plate 7 in a manner close to the telecentric optical system, and color bleeding is also prevented.

M) 및 구결상면만곡(

S)왜곡 및 배율색수차로 도시된다. 또한, 제2실시예의 각 줌단계에서의 수차도 제3도와 같이 도시된다.According to the above configuration and operation, the aberration diagrams of the wide-angle step and the telephoto step of the first embodiment are spherical aberration of d line (wavelength 0.5876 μm) and F line (wavelength 0.4861 μm) as shown in FIG. Spherical Aberration, Meridian Top Curve

M) and curvature surface curvature (

S) Distortion and magnification chromatic aberration. Also, the aberration in each zoom step of the second embodiment is shown as shown in FIG.

M) 과 구결광속에 의한 만곡(

S)을, 세로축은 주광선의 각도를 나타내며, 왜곡수차는 물점의 광축으로부터의 거리에 대한 배율을 도시한 것으로 그래프의 가로축은 백분왜곡수차, 세로축은 입사하는 주광선의 각도이다.Here, spherical aberration is light beam height aberration on the upper surface with respect to the light beam incident in parallel with the optical axis, the horizontal axis of the graph is the beam height on the upper surface, the vertical axis is the incident height. OSO (offence against sine condition) is an amount indicating deviation from the sine condition, which is a condition for correcting spherical aberration and coma aberration at the same time. The horizontal axis is aberration amount and the vertical axis is incident light height. In addition, astigmatism is an aberration that cannot be formed at a point where the influence of the meridian beam (the light beam in the plane including the optical axis and the chief ray) and the spherical light beam (the ray perpendicular to the meridian beam including the chief ray) is not formed at one point. Where the horizontal axis is the curvature

M) and curvature due to the sphered beam

S), the vertical axis represents the angle of the chief ray, the distortion aberration shows the magnification with respect to the distance from the optical axis of the object point, the horizontal axis of the graph is the percent distortion, and the vertical axis is the angle of the incident chief ray.

Therefore, according to the present invention, the focus is corrected for the movement of the shop according to the movement of the water point, the image formation magnification of the fixed shop is changed in the displacement unit, the compensation unit is corrected for the movement of the store due to the displacement, axial aberration in all phases Since correction and off-axis aberration correction are performed at the rear of the image, the zoom lens can be maximized with the minimum lens forming the zoom lens, and the zoom range can be expanded with a high magnification of 8 times the zoom ratio.

In addition, the camera lens (optical system) has a large aperture of F / # = 1.4 to 1.8, so that even a relatively dark subject can be photographed, and the aberration correction state and the small size can be obtained. It is also expected to have an excellent effect to prevent color bleeding in the imaging phase due to the close centric composition.

Claims (1)

Focusing unit (3) for precisely focusing the object, the variation unit (4) for changing the magnification of the image, the compensation unit (5) for compensating the store according to the variation and the image forming unit to form the image of the upper surface In the zoom lens composed of (6), the focus portion (3) is composed of a concave lens (11) as a conjoined lens, a convex lens (12), and a convex lens (13) as a single lens, and the variable magnification portion (4) is short. It consists of a concave lens 14, which is a lens, and a conjoined lens of the concave lens 15 and the convex lens 16. The compensating part 5 is a concave lens 17, and the image forming part 6 is an image forming part 8. We have three convex lenses (18, 18 ', 19'), one concave lens (19) and two convex lenses (20, 21) and one concave lens (22) forming an image forming back (9). The stop surface 10 is formed between the convex lenses 18 and 18 'of the image forming front 8, ① 4.4≤ R ₁₇ / R ₁₈ ≤ 10.0 ② 3.0 ≤ R ₂₅ / R ₂₆ ≤ 3.4 ③ 0.15 ≤ D ₁₇ / fwide ≤ 0.22 ④ 0.05≤ D ₂₅ / fwide ≤ 0.08 ⑤ 12.0 ≤ TL / fwide≤ 13.0 Zoom lens for color video camera, characterized in that to satisfy the conditions of Ri (i = 1,2… n) is the radius of curvature of the i-th lens surface from the object Di (i = 1,2… n) is the lens thickness (or air gap) between the i-th plane and the next plane. TL is the distance in air from the first lens to the image fwide is the focal length at the wide-angle level (WIDE) during the zoom phase.

Images