JPH06186477A - Zoom lens with flare diaphragm - Google Patents

Abstract

PURPOSE:To provide a zoom lens capable of avoiding mechanical interference, of efficiently removing the flare, of easily obtaining the high optical performance over a whole variable power range and having a small sized and simply constituted flare diaphragm as a whole. CONSTITUTION:This lens comprises four lens groups of a first, a second, a third and a fourth groups having positive, negative, positive and positive refractive powers in the order from the object side, respectively, passes through the point at which the image forming powers of the second group L2 and the third group L3 simultaneously become -1 times at the time of varying the power from a wide-angle to a telephoto ends, a moving diaphragm I moves by using a moving mechanism in relation to the movement of the third group L3 so as to decrease the interval up to the second group L2 at the time of varying the power from the wide-angle end to the vicinity of the starting point of a F drop and moves by utilizing a mechanical means for reducing the interval up to the third group L3 at the time of varying the power from the vicinity of the starting point of the F drop to the telephoto end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens having a flare diaphragm suitable for a TV camera, a photographic camera, a video camera, etc., and more particularly to one of off-axis light beams which causes flare and halo upon zooming. The present invention relates to a zoom lens having a flare diaphragm in which a flare diaphragm (moving diaphragm) that blocks light is arranged in a lens system and is moved appropriately with zooming to obtain good optical performance over the entire zoom range. It is a thing.

[0002]

2. Description of the Related Art As a zoom lens having a higher zoom ratio than ever before,
From the object side, in order from the object side, a first group having a positive power (refractive power) for focus adjustment, a second group having a negative power and moving in the optical axis direction due to a zooming effect (variator), Four lenses, a third lens group (compensator) having a positive power and moving in the optical axis direction for zooming and image plane compensation, and a fourth lens group having a positive power and fixed and forming an image. Various so-called four-group type zoom lenses have been proposed which have a group and are set so that the variator and the compensator simultaneously have an imaging magnification of -1 when zooming from the wide-angle end to the telephoto end. There is.

When zooming from the wide-angle end to the telephoto end, this 4-group type zoom lens forms a large amount of coma flare in off-axis rays from a zoom position slightly on the telephoto side to an intermediate zoom position from the wide-angle end. There is a property that performance is reduced.

FIG. 13 is a schematic diagram showing optical elements and optical path states at the wide-side zoom position in which a large amount of coma flare is likely to occur in the above-mentioned four-group type zoom lens.

In the figure, ray tracing is performed on the on-axis F-number rays and off-axis rays reaching the maximum image height on the screen.

Now, let us say that the center of the off-axis ray is the principal ray and the ray below it is the underline.
It passes considerably below the optical axis of the lens on the diaphragm surface J that determines the number, and the underline passes through a position with a high height from the optical axis in the first group and the compensator (third group). It will be. As a result, it receives a strong positive refracting power and is flipped up, resulting in a large amount of coma flare aberration.

A zoom lens having means for solving this problem is proposed in, for example, Japanese Patent Publication No. 51-21794 and Japanese Patent Publication No. 56-52291.

In Japanese Patent Publication No. 51-21794, a lens barrel is fixed between a variator and a compensator.
The underlined flare component is cut by setting a variable diameter diaphragm and changing the size of the diameter according to zooming.

In Japanese Patent Publication No. 56-52291, a diameter-invariant moving diaphragm is provided between the variator and the compensator, and the diaphragm is moved in association with the variator so that the underline in the middle of the screen is reduced in the entire zoom range. A zoom lens with a cut section has been proposed.

[0010]

Generally, in order to effectively eliminate aberration fluctuations generally associated with zooming, especially flare fluctuations, when the flare diaphragm is arranged in the lens group, the flare is not blocked by the axial light flux. It is necessary to displace it only in a position where it can be effectively removed.

In the zoom lens proposed in Japanese Patent Publication No. 51-21794, the diaphragm diameter must be controlled mechanically or electrically in accordance with zooming, which makes the mechanism complicated and large. In addition, it is necessary to secure a mechanical space so that the diaphragm mechanism and the variator and compensator do not interfere with each other at the tele end, which causes a problem that the zoom lens becomes large and costly. It was

In the zoom lens proposed in Japanese Examined Patent Publication No. 56-52291, the necessary conditions and means for cutting only the light rays in the portion where the aberration is deteriorated according to the change of the aberration are disclosed. However, in the embodiment shown in the publication, a part of the underline is cut by the moving diaphragm over the entire zoom range, so that even a useful ray whose aberration is favorably corrected may be cut. There was a problem that it would occur.

According to the present invention, in a four-group type zoom lens, a flare diaphragm (moving diaphragm) provided between a variator and a compensator that move during zooming is set at an appropriate position and an aperture diameter, and zooming is performed. In this case, by moving on the optical axis so as to satisfy the predetermined condition, mechanical interference is avoided, flare is effectively removed, and high optical performance is easily obtained over the entire zoom range. An object of the present invention is to provide a zoom lens having a small and simple flare diaphragm.

[0014]

A zoom lens having a flare stop according to the present invention comprises, in order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power having a zooming action, and an aperture diameter. It has four lens groups of a constant moving diaphragm, a third lens group having a positive refractive power for correcting an image surface which varies due to a zooming action and a zooming, and a fourth lens group having a positive refractive power having an image forming action, Upon zooming from the wide-angle end to the telephoto end, the imaging magnifications of the second group and the third group simultaneously pass through a point of −1, and the movable diaphragm is zoomed from the wide-angle end to the F drop start point. Moves using a moving mechanism related to the movement of the third lens unit so that the distance between the second lens unit and the second lens unit becomes small, and when moving from the vicinity of the F drop start point to the telephoto end, It is characterized in that it is moved by using a mechanical means such that the interval becomes small.

In particular, the movable diaphragm has an aperture diameter of D, an effective diameter of the final lens surface of the second group is Dv, an effective diameter of the object-side first lens surface of the third group is Dc, and an F drop start point. At the distance between the final lens surface of the second lens group and the first lens surface of the third lens group on the object side, and the moving diaphragm at the F drop start point and the first lens surface of the third lens group on the object side. The distance to the lens surface is X
When it is set to o, it is characterized in that Dv <D <Dc 1/3 * S ≦ Xo.

[0016]

1 is a sectional view of an essential part of an optical system according to a first embodiment when the present invention is applied to a TV camera, and FIGS. 14 and 15 show a part of the lens of FIG. 1 for showing the optical function of the present invention. 14 is a sectional view, FIG. 14 shows the wide side, and FIG. 15 shows the F drop start point (zoom position where the F number increases when zooming from the wide-angle end to the telephoto end).

In the figure, L1 is a first group having a positive power, which moves in the optical axis direction when focusing on an object and is fixed during zooming. L2 is a second group (variator) having negative power, which moves in the optical axis direction during zooming.

L3 is a third group (compensator) having a positive power, which moves in the optical axis direction during zooming for the purpose of zooming and image plane compensation. L4 is a fourth lens group (relay lens) having a positive power and acts as an image forming element.
P is a 3P prism as a color separation optical system, and is shown as an optical block.

Here, J is a diaphragm with a variable aperture diameter that determines the F number of the zoom lens, and I is a flare diaphragm (moving diaphragm) according to the present invention with a constant aperture diameter.

First, the optical function of the zoom lens of the present invention will be described. The present invention is a zoom lens of the four-group type having four lens groups as shown in FIG. 1, and particularly in the middle zoom range (a little on the tele side from the wide end in the zoom range from the wide-angle end to the telephoto end). In the zoom range from the zoomed position to the F drop start point), only the underlined aberration-increasing portion is cut by the flare diaphragm that moves with the zooming operation.

That is, at the wide end, the light rays effective for performance are not cut, and at the zoom area from the F drop start point to the tele end, the light rays of the axial F number are not cut.

For this purpose, the diameter of the flare stop I is set so as not to cut the F number ray at the F drop start point, and in the intermediate zoom range where the aberration of the underline increases, only the underline is effective by the flare stop I. It is moved to a position where it can be cut.

That is, in this embodiment, as shown in FIG. 1, the flare stop I is moved integrally from the wide side to the F drop start point in the forward direction (object side) in association with the movement of the compensator L3. .

On the telephoto side from the F drop start point, in order to avoid mechanical interference with the variator L2, the distance from the F drop start point is moved toward the image plane side so as to narrow the gap with the compensator L3.

Next, the features of this embodiment will be described with reference to FIGS. 15, between the variator L2 and the compensator L3, the axial F-number ray 15a passes substantially outside the underline 15b of the off-axis ray, while in FIG.
b passes through the outside of the axial F-number ray 15a.

In the present invention, this difference is utilized, and the flare stop is designed to effectively cut the underline 15b of the off-axis rays on the wide side without cutting the on-axis F-number ray 15a at the F drop start point. The position of I is set. The shaded portion shown in FIG. 14 is a portion of the off-axis light ray that is cut by the flare stop I.

As can be inferred from FIG. 14, the position where the flare diaphragm I is arranged is such that the diameter of the flare diaphragm I becomes larger as the flare diaphragm I is arranged farther from the compensator L3 under the condition that the axial F-number ray 15a is not cut. It can be made smaller and the effect of cutting underlines can be increased. However, for the diameter of the flare stop I, the on-axis F-number ray 1 in FIG.
There is a restriction for not cutting 5a.

The on-axis F number ray (ray 15a in FIG. 15) at the F drop start point is the variator L2.
And the effective diameters of the final lens surface and the first lens surface of the compensator L3 are determined. Therefore, since the on-axis F-number ray on the wide side (ray 15a in FIG. 14) passes inside the off-axis ray 15b, the diameter of the flare stop I is D, the effective diameter of the final lens surface of the variator L2 is Dv, and , Dv <D <Dc ... (1) when the effective diameter of the first lens surface of the compensator L3 is Dc.

When the condition value is not satisfied and D <Dv is satisfied, the flare stop I cuts the axial F-number light beam 15a, and when D> Dc, the underline 15b cannot be cut. Therefore, it is preferable to determine the diameter D of the flare stop on the basis of the axial F number ray 15a at the F drop start point. When the distance between the final lens surface of the variator L2 and the first lens surface of the compensator L3 at the F drop start point is S, and the distance between the diaphragm at the F drop start point and the compensator L3 is Xo, D = (Dv-Dc) / S * Xo + Dc. Further, the position of the flare diaphragm at the F drop start point is preferably 1/3 * S ≦ Xo (2), and when Xo <1/3 * S, the F drop start point Since the difference in height between the axial F-number ray 15a and the wide-side underline becomes small, the underline cannot be effectively cut. Further, at the wide-side zoom position (FIG. 14), the on-axis F-number ray 15a and the underline 1 are provided between the variator L2 and the compensator L3.
The difference in height from the optical axis of 5b increases as it approaches the variator L2 side, and the underline of this zoom position 15
Comparing the tilt angle of b (FIG. 14) and the tilt angle of the on-axis F-number ray 15a at the F drop start point (FIG. 15), the latter is larger, and therefore the height from the optical axis increases toward the variator L2 side. , The flare stop at the F drop start point should be closer to the variator L2.

Therefore, in the wide zoom range where it is necessary to cut the underline, the distance X from the compensator L3 to the flare stop is set to X≤S ... (3). If the condition is not satisfied and X> S, the height of the underline from the optical axis becomes low, and the effect of cutting the underline becomes small.

As described above, in the present embodiment, the aperture diameter of the flare stop and the moving condition are appropriately set in order to cut only the flare component. This gives a zoom lens with high optical performance.

Next, this embodiment will be described by giving specific numerical values. In the numerical examples described later, the flare diaphragm I
By means of moving means linked to the compensator L3, from the wide end to the F drop start point.
3 and a constant distance of 32 mm are maintained, and the object 3 is moved to the object side.
Then, it moves to the image plane side so that the distance between the variator L2 and the compensator L3 is narrowed while keeping a constant distance of 2.87 mm up to the telephoto end thereafter.

In this embodiment, S = 34.87 mm and Xo = 0.918S.

On the other hand, the final lens surface r of the variator L2
15 and the effective diameter of the first lens surface r17 of the compensator L3 are Dv = 34.6 mm and Dc = 55.3, respectively.
mm, which is determined by the on-axis F number ray 15a at the F drop start point. Since the diameter D of the flare stop I cannot be made smaller than the on-axis F number ray diameter at the F drop start point, it is determined by which position between the variator L2 and the compensator L3 the flare stop I is arranged.

In this embodiment, the above equations (1), (2),
From (3), a flare diaphragm having an opening diameter D = 35.5 mm is arranged at a position 32 mm from the compensator L3. With these configurations, flare is effectively removed.

Next, the moving mechanism for changing the magnification will be described. Particularly, in the zoom lens according to the present invention, at the time of zooming, the flare diaphragm I moves in conjunction with the moving mechanism of the compensator, and in order to avoid mechanical interference with the variator L2, the compensator on the telephoto side from the F drop start point. The moving mechanism is configured to reduce the distance from L3. 7 and 8 are a vertical cross-sectional view of the periphery of the compensator L3 for showing the moving mechanism of the present embodiment and an operation diagram showing the position change of each lens group due to zooming. Figure 8
In (A), the rays between the variator L2 and the compensator L3 represent off-axis rays, and the shaded portions thereof represent the rays cut by the flare diaphragm. The same figure (B),
The ray shown in (C) is an on-axis F-number ray.

In the figure, 1 is a holding barrel of the compensator L3, 2 is a holding barrel of the variator L2, and at one end thereof, a cam groove 3a and a cam groove provided on the cylindrical cam 3 based on an optical relationship. Rotating members 1a, 2a engaging with 3b, and rotating members 1b, 2b engaging with a linear groove 4 provided in the lens body (not shown) are attached to the other end of the cylindrical cam 3. With the rotation, it moves in the optical axis direction along the straight groove 4.

Here, in front of the compensator L3, a flare diaphragm I made of a ferromagnetic material and having a fixed diameter D is provided.
Is attached so as to smoothly and linearly move on the column 1c through a support member 5 that engages with the column 1c protruding from the lens barrel 1. Further, the tip of the column 1c is bent into an L shape, and the permanent magnets 6 and 7 for attracting the flare diaphragm I are attached to the diaphragm side and the image side end of the holding barrel 2 of the variator L2.
Is attached.

The magnets 6 and 7 have a magnetic force sufficient to attract the weight of the flare stop I so that the flare stop I does not fall under its own weight even when the zoom lens is directed upward and downward.

In the above structure, the flare stop I is attracted to the magnet 6 from the wide side shown in FIG. 8A to the variator L2 at the F drop start point in FIG. Move while keeping the distance between L3 and Xo.

When the magnification is further changed to the telephoto end, as shown in FIG. 8 (C), it is pushed out to the holding barrel 2 of the variator L2, separated from the magnet 6 on the compensator L3 side, and attracted to the magnet 7 on the variator L2 side. Move while reducing the distance from the sweater L3. The opposite operation is performed in the tele-to-wide direction.

9 and 10 are a longitudinal sectional view of a compensator L3 showing a moving mechanism of the second embodiment of the present invention, and an operation diagram showing the position change of each lens group by zooming.

The present embodiment is different from the first embodiment in that a pressing force of a spring is used for the moving mechanism of the flare diaphragm I, and other configurations are substantially the same. The same elements are given the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 9 and 10A, the flare diaphragm I is attached to the end 1d of the column 1c by a compression coil spring 8 provided on the outer peripheral surface of the column 1c protruding from the holding barrel 1 of the compensator L3. It has been pressed.

As with the first embodiment, the flare diaphragm I is shown in FIG.
As shown in 0, from the wide end to the F drop start point, it moves integrally with the compensator L3, and in the zoom area on the tele side from the F drop start point, the compensator L3 is pushed by the variator L2 while compressing the compression coil spring 8.
Move so as to narrow the distance X between and.

11 and 12 are a longitudinal sectional view of a compensator L3 showing a moving mechanism of the third embodiment of the present invention and an operation diagram showing the position change of each lens group by zooming.

In the figure, reference numeral 1 denotes a holding barrel of a compensator, which has a cam groove 1d on its outer peripheral surface. A cylindrical member 9 holds the flare stop I. A gear 10 is fixed to the cylindrical cam 3 and meshes with a gear portion 9a of the cylindrical member 9 to rotate the cylindrical member 9 as the cylindrical cam 3 rotates.

The cylindrical member 9 has a rotating member 9b which engages with the cam groove 1d of the holding barrel 1, and when changing the magnification, the cam groove 1d is formed.
The linear movement in the optical axis direction is performed so as to satisfy the above condition by being regulated by d.

As described above, in the present embodiment, the wide-angle end is set in the zoom lens in which the diameter-invariant flare diaphragm I is set between the variator L2 and the compensator L3, apart from the diaphragm that determines the F number of the zoom lens. From the zoom position on the slightly telephoto side to the zoom position near the F drop start point, the flare diaphragm I is moved to the object side by the moving mechanism related to the compensator L3, and the variator L2 is set on the telephoto side near the F drop start point. In order to avoid the mechanical interference of the zoom lens, a mechanism means for narrowing the interval between the flare diaphragm and the compensator L3 is provided, so that a zoom lens having a simple mechanism at a low cost and a large effect of improving the performance is obtained.

In the first and second embodiments, the flare diaphragm I is set to the compensator L from the wide end to the F drop start point.
However, this is not always necessary, and the interval may change. For example, in the third embodiment, the cam groove is appropriately set, and the conditional expressions (2) and (3) described above are set.
By satisfying the condition, it is possible to give a movement locus for effectively cutting the underline.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number.

Tables 1 and 2 show the relationship between the focal length and the variable distance in the numerical examples, and Table 1 shows the position of the flare stop I at the F drop start point as Xo = 32 mm.
Table 2 shows the case where Xo = 16 mm.

2 (f = 10 mm), FIG. 3 (f = 19, 49 mm), FIG. 4 (f = 69.78 mm), and FIG. 5 (f = 200. 23 m
m) As shown in FIG. 6 (f = 440 mm).

In the aberration diagram, the left side of the shaded portion is cut, and the numerical values attached above the shaded portion correspond to the case where the numerical value 1 is in Table 1 and the numerical value 2 is in Table 2. From the aberration diagram, it can be seen that the effect of cutting the flare component underlined most is great in the vicinity of f = 19.49 mm and f = 69.78 mm. (Numerical example) f = 10.00 to 440.0 Fno = 1: 1.75 2ω = 57.6 ° R 1 = 376.21 D 1 = 5.50 N 1 = 1.72311 ν 1 = 29.5 R 2 = 177.11 D 2 = 0.70 R 3 = 176.93 D 3 = 23.10 N 2 = 1.43496 ν 2 = 95.1 R 4 = -669.49 D 4 = 0.30 R 5 = 176.40 D 5 = 18.90 N 3 = 1.43496 ν 3 = 95.1 R 6 = -2349.39 D 6 = 0.30 R 7 = 132.49 D 7 = 11.53 N 4 = 1.49845 ν 4 = 81.6 R 8 = 249.61 D 8 = Variable R 9 = 654.82 D 9 = 2.00 N 5 = 1.82017 ν 5 = 46.6 R10 = 66.97 D10 = 3.79 R11 = -2513.70 D11 = 1.80 N 6 = 1.77621 ν 6 = 49.6 R12 = 53.55 D12 = 6.67 R13 = -64.98 D13 = 1.80 N 7 = 1.82017 ν 7 = 46.6 R14 = 45.67 D14 = 5.49 N 8 = 1.93306 ν 8 = 21.3 R15 = 353.68 D15 = Variable R16 = ∞ (Aperture) D16 = Variable R17 = -1012.25 D17 = 6.00 N 9 = 1.50014 ν 9 = 65.0 R18 = -101.88 D18 = 0.30 R19 = 198.87 D19 = 2.50 N10 = 1.65223 ν10 = 33.8 R20 = 78.98 D20 = 11.36 N11 = 1.59143 ν11 = 61.2 R21 = -139.10 D21 = 0.20 R22 = 158.86 D22 = 9.85 N12 = 1.60548 ν12 = 60.7 R23 = -94.56 D23 = 2.50 N13 = 1.85501 ν13 = 23.9 R24 = -202.34 D24 = 0.20 R25 = 88.25 D25 = 6.31 N14 = 1.48915 ν14 = 70.2 R26 = 316.08 D26 = variable R27 = ∞ (aperture) D27 = 4.11 R28 = -55.89 D28 = 1.80 N15 = 1.79013 ν15 = 44.2 R29 = 39.88 D29 = 4.44 N16 = 1.81265 ν16 = 25.4 R30 = 176.36 D30 = 5.84 R31 = -34.79 D31 = 1.60 N17 = 1.73234 ν17 = 54.7 R32 = 33.38 D32 = 10.57 N18 = 1.59911 ν18 = 39.2 R33 = -29.57 D33 = 24.00 R34 = -625.77 D34 = 6.26 N19 = 1.48915 ν19 = 70.2 R35 = -33.03 D35 = 0.20 R36 = -56.24 D36 = 2.20 N20 = 1.79013 ν20 = 44.2 R37 = 36.97 D37 = 7.66 N21 = 1.81265 ν21 = 56.4 R38 = -60.83 D38 = 1.10 R39 = 203.13 D39 = 7.32 N22 = 1.55099 ν22 = 45.8 R40 = -29.08 D40 = 2.20 N23 = 1.81265 ν23 = 25.4 R41 = -94.79 D41 = 0.20 R42 = 78.68 D42 = 6.15 N24 = 1.51977 ν24 = 52.4 R43 = -61.86 D43 = 5.00 R44 = 0.00 D44 = 50.00 N25 = 1.51825 ν25 = 64.2 R45 = 0.00

[0055]

[Table 1] D = 35.5 Xo = 0.918S

[0056]

[Table 2] D = 45.5 Xo = 0.459S

[0057]

EFFECTS OF THE INVENTION According to the present invention, the lens moves during zooming.
When changing the magnification of the flare diaphragm (moving diaphragm) provided between the two lens groups, by moving on the optical axis so as to satisfy a predetermined condition, mechanical interference is avoided and flare is effectively removed. It is possible to achieve a zoom lens having a flare diaphragm having a small size and a simple structure as a whole, which can easily obtain high optical performance over the entire zoom range.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens according to a first embodiment of the present invention.

FIG. 2 is a diagram of various aberrations at the wide-angle end according to a numerical example of the present invention.

FIG. 3 is an intermediate (f = 19.49) numerical example of the present invention.
mm) aberration diagrams

FIG. 4 is an intermediate example (f = 69.78) of the numerical embodiment of the present invention.
mm) aberration diagrams

FIG. 5 is a diagram of various types of aberration at the F drop start point in the numerical example of the present invention.

FIG. 6 is a diagram of various aberrations at the telephoto end according to the numerical example of the present invention.

FIG. 7 is a vertical sectional view showing the moving mechanism according to the first embodiment of the present invention.

FIG. 8 is an operation diagram of the moving mechanism according to the first embodiment of the present invention.

FIG. 9 is a vertical sectional view showing a moving mechanism according to a second embodiment of the present invention.

FIG. 10 is an operation diagram of the moving mechanism according to the second embodiment of the present invention.

FIG. 11 is a vertical sectional view showing a moving mechanism according to a third embodiment of the present invention.

FIG. 12 is an operation diagram of a moving mechanism according to a third embodiment of the present invention.

FIG. 13 is a lens cross-sectional view of a conventional zoom lens

FIG. 14 is a sectional view of a lens on the wide side for showing an optical function of the present invention.

FIG. 15 is a lens cross-sectional view of an F drop start point for showing an optical effect of the present invention.

[Explanation of symbols]

 1 Holding lens barrel of compensator L3 2 Holding lens barrel of variator L2 3 Cylindrical cam 4 Straight groove 5 Support member 6,7 Magnet 8 Compression coil spring 9 Cylindrical member 10 Gear I Flare diaphragm (moving diaphragm) P prism L1 1st group L2 Second group (variator L2) L3 Third group (Compensator L3) L4 Fourth group

Claims (2)

[Claims] 1. A first lens unit having a positive refractive power in order from the object side, a second lens unit having a negative refractive power having a zooming action, an aperture diameter-invariable moving diaphragm, and an image surface fluctuating due to a zooming action and a zooming action. Has a fourth lens unit having a positive refracting power for compensating the optical power and a fourth lens unit having a positive refracting power having an image forming action, and the second lens unit at the time of zooming from the wide-angle end to the telephoto end. And the image forming magnification of the third lens group simultaneously passes through a point of −1, and the moving diaphragm uses a moving mechanism related to the movement of the third lens group when changing the magnification from the wide angle end to the vicinity of the F drop start point. And moves so as to reduce the distance from the second lens unit, and when changing the magnification from the vicinity of the F drop start point to the telephoto end, using a mechanism such that the distance to the third lens unit decreases. A zoom lens with a flare diaphragm. 2. An aperture diameter of the movable diaphragm is D, an effective diameter of a final lens surface of the second group is Dv, an effective diameter of a first lens surface of the third group on the object side is Dc, and an F drop start point. At the final lens surface of the second lens group and the first lens surface of the third lens group on the object side.
When the distance from the lens surface is S, and the distance between the movable diaphragm at the F drop start point and the first lens surface on the object side of the third lens unit is Xo, Dv <D <Dc 1/3 * S ≦ The zoom lens with the flare diaphragm according to claim 1, wherein Xo is set.