JPH07110446A - Zoom lens - Google Patents

Abstract

PURPOSE:To accurately follow an object by simple control and to attain excellent operability by providing a focusing means obtained based on a mechanism realizing such relation between a focal distance and an object distance that image magnification is maintained. CONSTITUTION:An image magnification set means is constituted of a rotary barrel 5, an image magnification set unit 6, an image magnification set key 7, an image magnification set and communication barrel 8, a first-group lens barrel 9, a zoom ring 10, a zoom driving unit 11, a cam barrel 13 or the like. The focusing means is constituted of lens barrels 9, 14 and 15-17 or the like respectively holding a first lens I to a sixth lens VI. When the image magnification is set by such constitution, it is not occurred the change of the image magnification caused by zooming. Simultaneously, a countermeasure can be executed with respect to the change of a photographing distance without changing the image magnification in the midst of zooming operation. Then, since the work of the zooming operation is provided with the function of focusing operation executed after the magnification is set, the focusing function is also realized in the case that the zooming operation is fixed and the setting angle of the image magnification is adjusted and the way of zoom-lens use is also realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens which is convenient for tracking an object so as to keep it at a specific size or projecting it on a specific size (screen).

[0002]

2. Description of the Related Art A conventional zoom lens of this type is often used together with an autofocus (hereinafter referred to as AF) function, and in order to make an object follow a specific size, a first zoom lens is used. To temporarily set the focal length, secondly to perform AF distance measurement (focusing operation), thirdly to calculate the focal length for achieving the target image magnification, and fourth to set the focal length based on the above calculation result, 5
It was necessary to take steps such as focusing check.

[0003]

However, in the above-mentioned conventional example, In order to follow an object moving at high speed with a specific size, that is, with a constant image magnification, it is necessary to control the zoom mechanism and the AF mechanism at the same time, which is difficult. In a zoom lens that does not have an AF mechanism, it is necessary to perform zooming drive and focus operation while checking the image size with the viewfinder of the camera. It is extremely difficult to follow up under the circumstances. In the case of a projector, there was a problem that it was necessary to set the image size by zooming after confirming the focus on the screen.

It is an object of the present invention to obtain a zoom lens that solves the above-mentioned conventional problems.

[0005]

According to the present invention, an image magnification setting means capable of a focusing operation, and a focal length and a subject distance for maintaining a specific image magnification set by the image magnification setting means. By providing the focusing means based on the mechanism for realizing the relationship, it is possible to obtain a zoom lens which is capable of highly advanced subject tracking with simple control and has excellent operability.

[0006]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings.

1 to 12 show a first embodiment of the present invention, FIG. 1 is a sectional view showing a tele end state of a lens, FIG. 2 is a sectional view showing a wide end state of a lens, and FIG. 3 is a cam barrel. FIG. 4 is an exploded view of the fixed barrel, FIG. 5 is an exploded view of the fitting portion of the fifth group lens barrel, FIG. 6 is a developed view of the first group barrel, and FIG. 7 is a developed view of the image magnification setting connecting barrel. FIG. 8 is a diagram showing the amount of extension DX of the image magnification setting group at the time of zooming, FIG. 9 is a zoom movement diagram during zooming of each zoom group, and FIG. 10 is a detailed view around the image magnification setting cam. 11 is a diagram showing the zoom parameter (Zp), the image magnification and the shooting distance at the image magnification setting angle.

Incidentally, FIG. 12 shows the zoom parameter (Zp).
FIG. 7 is a diagram showing a state of image magnification and shooting distance at an image magnification setting angle for a conventional example.

1 to 11, reference numeral 1 denotes a fixed cylinder, and the fixed cylinder 1 has an outer surface straight-moving groove 1 as shown in FIG.
a, the inner straight groove 1b, the holding hole 1c of the second lens group II,
Three pieces are provided for each. Also, small diameter part 1
The h has a peripheral hole 1i.

Reference numeral 2 denotes a mount, which is fixed to the fixed cylinder 1 with a screw 2a and has a back cover 3
And has a detachable stopper pin 2b.

The fixed cylinder 1 has a magnification window portion 4 in the large diameter portion 1e, a step portion 1f and a fitting portion 1g on the inner surface of the large diameter portion 1e, and the step portion 1f and the fitting portion 1g. The rotary cylinder 5 is rotatably held at 1 g. The rotary cylinder 5 has an image magnification setting portion 5a at the front end, and also has a rear end inner peripheral portion 3
It has a protruding portion 5b at a location.

An image magnification setting unit 6 includes an image magnification setting unit body (hereinafter referred to as a unit body) 6a.
Is fixed to the fixed barrel 1 with screws 6b. 6c
Is a known ultrasonic motor. 6d is an output member, 6e
Is a roller member, and this roller member 6e is a roller ring 6g.
Axial screws 6f are rotatably held on the outer periphery of the shaft in three equal parts. The roller ring 6g has an inner diameter fitted into the unit body 6a and is rotatably held, and a magnification scale 6i is provided on the outer peripheral portion.

Further, 6h is an intermediate member, and this intermediate member 6h is fitted and held by the unit body 6a, and has three fitting vertical groove portions 6j on the outer peripheral portion thereof. The rotary cylinder 5 fits with the projection 5b on the inner peripheral portion of the rear end of the rotary cylinder 5, and can rotate together with the rotary cylinder 5. Reference numeral 6k denotes a pressing member of the ultrasonic motor 6c, and the ultrasonic motor 6c and the output member 6 are included in the unit main body 6a.
d, the roller member 6e, and the intermediate member 6h are simultaneously pressed in order.

That is, by this mechanism, either the magnification setting section 5a at the tip of the rotary cylinder 5 is rotated, the ultrasonic motor 6c or the output member 6d is rotated, or both are performed at the same time. The rotation can be transmitted to the roller ring 6g of the image magnification setting unit 6 described above.

An image magnification setting key (hereinafter referred to as a key) 7 is fixed to the roller ring 6g in the image magnification setting unit 6 with a screw 7a. The key 7 has a fitting vertical groove portion 7b (not shown).

Reference numeral 8 denotes an image magnification setting communication tube, and this image magnification setting communication tube 8 is fitted to the inner surface of the fixed cylinder 1 as shown in FIG. Further, it has a vertical groove 8b on the inner peripheral surface.
The pin 8a is screwed into the outer peripheral surface of the image magnification setting communication tube 8, and at the same time, the peripheral hole 1 of the small diameter portion 1h of the fixed tube 1
The thrust is regulated by i, and the rotation is regulated by the fitting vertical groove portion (hereinafter referred to as a key) 7b (not shown) of the key 7.

Reference numeral 9 denotes a first group lens barrel, and this first group lens barrel 9 is
While holding the group lens I, it is fitted with the fixed cylinder 1 at the fitting portion 9a on the inner surface of the rear end thereof, and at the same time, a straight key 9b is fixed to the inner surface of the rear end by a screw 9c. By fitting the straight-movement key 9b into the outer surface straight-movement groove 1a of the fixed barrel 1, the straight-movement key 9b is held so as to be able to move straight with respect to the fixed barrel 1. Further, as shown in FIG. 6, the first-group barrel 9 has three inner surface cam grooves 9d in the front half portion thereof, and screws 9e are provided on the rear outer peripheral portion thereof.

Reference numeral 10 denotes a zoom ring, which is rotatably held with respect to the fixed barrel 1.
Further, a female screw 10b is provided on the inner surface portion and is screwed with a male screw 9e provided on the rear outer peripheral portion of the first group lens barrel 9. Further, the zoom ring 10 has a focus operating portion 10c on the outer peripheral portion of the front end and a gear portion 10d on the inner peripheral portion of the rear end.

A zoom drive unit 11 has an output gear 11a, and this output gear 11a is in mesh with a gear portion 10d of the zoom ring 10. Further, the zoom drive unit 11 can rotate the zoom ring 10 by inputting a drive signal, and at the same time, can give a back-and-forth movement to the first-group barrel 9. Moreover, the zoom ring 1
Reference numeral 0 is provided with an encoder (not shown) capable of detecting the rotation amount with respect to the fixed barrel 1.

It should be noted that the output gear 11a of the zoom drive unit 11 becomes free rotation when a drive signal is not input to the zoom drive unit 11, and by rotating the focus operating portion 10c described above, The zoom ring 10 can be rotated.

Reference numeral 13 denotes a cam barrel, which has a large-diameter portion 13a as shown in FIG.
3a is fitted and held in the inner diameter of the fixed barrel 1, and is also fixed pin cam 13c, third group cam 13d, fourth group cam 1
3e and 5 group cams 13f are provided in three equal parts. An image magnification setting cam 13g is provided on the small diameter portion 13b.

Further, there is a fitting portion 13h having a large one-step diameter on the outer peripheral portion of the front end of the cam barrel 13, and fitting pins 13i are equally screwed into three places on the outer surface of the fitting portion 13h. . The fitting pin 13i is engaged with the inner cam groove 9d of the first group lens barrel 9 described above.

Reference numeral 14 denotes a second group lens barrel, and this second group lens barrel 14
Holds the second lens group II and has a fitting portion 14a on the outer circumference.
The fitting portion 14a is provided with three fixing pins 14b at equal positions. The fixing pin 14b provided on the fitting portion 14a is the large diameter portion 13a of the cam barrel 13.
At the same time as engaging with the fixed pin cam 13c provided on the
The second group holding hole 1c provided in the fixed barrel 1 is engaged. Therefore, the second group lens barrel 14 is fixed to the fixed barrel 1.

Further, the cam barrel 13 is rotated by a two-position element in the shape of a fixed pin cam 13c provided on the large diameter portion 13a and an inner cam groove 9d provided on the front half of the first group lens barrel 9. After that, the thrust position is determined, and after adding the above description, the cam barrel 13 eventually performs the rotational extension operation by the back-and-forth movement of the first-group barrel 9. A movable diaphragm 13j is fixed to the front end surface of the cam barrel 13.

Reference numeral 15 denotes a fifth-group lens barrel, and this fifth-group lens barrel 15
As shown in FIG. 5, holds the fifth group lens V, has a fitting portion 15a, and is fitted and held in the large diameter portion 13a of the cam barrel 13. Further, the fitting portion 1 of the fifth-group barrel 15
The fifth group pin 15b is screwed into the 5a, and three third group grooves 15c and four third group grooves 15d are equally provided.

In the fifth-group barrel 15, the fifth-group pin 15b screwed into the fitting portion 15a has a large-diameter portion 13 of the cam barrel 13.
Since the fifth-group cam 13f provided in a and the inner surface rectilinear groove 1b of the fixed barrel 1 are simultaneously engaged, the above-mentioned cam barrel 13
It is possible to perform a predetermined zoom movement by the rotational extension operation of.

Reference numeral 16 is a known electromagnetic diaphragm unit. 1
Reference numeral 7 is a third group lens barrel, and this third group lens barrel 17 is a third lens group.
It holds III and the electromagnetic diaphragm unit 16. or,
The third group lens barrel 17 is fitted and held in the fifth group lens barrel 15, and the third group pin 17a screwed into the fitting surface is provided in the fifth group lens barrel 15.
Third group groove 15c provided in the fitting portion 15a of the group barrel 15
And the third group cam 13 provided on the large diameter portion of the cam barrel 13.
Since it is engaged with d at the same time, a predetermined zoom movement can be performed in a straight line by the above-mentioned rotational extension operation of the cam barrel 13.

Reference numeral 18 denotes a fourth group lens barrel, and this fourth group lens barrel 18
Holds the fourth lens group IV. Also, the 5th lens barrel 1
The fourth group pin 18a which is fitted and held in the fifth group and is screwed into the fitting surface is provided with the fourth group groove 15d provided in the fitting portion 15a of the fifth group lens barrel 15 and the large diameter portion of the cam barrel 13. Since they are simultaneously engaged with the fourth group cam 13e provided in the above, the predetermined zoom movement can be performed by the rotational extension operation of the cam barrel 13 as in the case of the third group lens barrel 17.

Reference numeral 19 denotes a 6-group lens barrel, and this 6-group lens barrel 19
Holds the sixth lens group VI, is fitted and held on the inner surface of the small diameter portion 13b of the cam barrel 13, and the sixth group pin 19a screwed into the fitting portion of the sixth group lens barrel 19 is The image magnification setting cam 13g provided on the small diameter portion 13b of the cam barrel 6 and the vertical groove 8 on the inner peripheral surface of the image magnification setting communication barrel 8.
It is engaged with b and positioned.

In the first embodiment, the rotary barrel 5, the image magnification setting unit 6, the image magnification setting key 7, the image magnification setting communication barrel 8, the first group lens barrel 9, the zoom ring 10, the zoom drive unit 11, the cam. The image magnification setting means is constituted by the cylinder 13 and the like, and each of the lens barrels 9, 14 for holding the first lens group I to the sixth lens group VI.
The focusing means is composed of 15, 17 to 19 and the like.

FIG. 8 is a graph showing the extension amount DX of the sixth lens group, which is the image magnification setting group, with reference to the movement of the sixth lens group at image magnification = 0 (infinity). The solid line shows a curve of equal image magnification, and the broken line shows a curve of equal shooting distance, with the parameter and the vertical axis as the lens extension amount (movement amount).

In this embodiment, the image magnification setting cam 13g defined by the equation 14 is determined on the basis of the extension amount representing the equal image magnification as represented by the equations 3 to 13 described later.

FIG. 9 shows a zoom movement diagram, in which the movement of each group is: P = 0 at the wide end, and P = 0 at the tele end.
The zoom parameter is changed to P = 1, and is represented by P.

The first group is a substantially straight line feeding,
Moving amount: Z1 (P) is expressed as a function of P, Z1 (P) = − 877.7291 × P¹  -5.9751 x P²  +38.2270 x P³  -18.8765 x P^Four  -7.2885 x P^Five  +6.64197 x P⁶ (Formula 1)

The second group is a fixed group. The third to fifth groups are non-linearly extended. The sixth lens unit also moves out in a non-linear manner, and in the present embodiment, the sixth lens unit is also used for the image magnification setting operation. Therefore, the image magnification = 0 state (infinity photographing state,
Hereinafter, the zoom movement amount in the infinity state) is represented by a function Z6 (P) of P similarly to the zoom movement amount Z1 (P) of the first group, Z6 (P) = − 52.2729 × P ¹ +23.3911 × P ² +39.3588 × P ³ -236.458 × P ⁴ +530.4948 × P ⁵ −580.5656 × P ⁶ +292.4738 × P ⁷ −56.326298 × P ⁸ (Equation 2).

Further, the amount of extension in the image magnification setting of the sixth lens group is considered for each image magnification setting value by using the above-mentioned Z6 (P) as a reference position, and when expressed by DX (P), the distance is infinite. The amount of extension for each image magnification is expressed as follows. DX (P) 0% = 0 (Equation 3) DX (P) 2% = +0.26578288 +0.32677579 XP ¹ +0.48761935 XP ² -0.14211975 XP ³ +1.33003314 XP ⁴ -2.71535629 XP ⁵ +4.25813041 XP ⁶ -3.33968100 XP ⁷ +0.88264237 XP ⁸ (Equation 4) DX (P) 4% = +0.53293827 +0.65529953 XP ¹ +1.00527252 XP ² -0.52327259 XP ³ +3.76205789 XP ⁴ -7.95733190 XP ⁵ 11.63453563 XP ⁶ -8.60568297 XP ⁷ +2.22877404 XP ⁸ (Equation 5) DX (P) 6% = +0.80149430 +0.98515962 XP ¹ +1.55549549 XP ² -1.10709724 XP ³ +6.98479504 XP ⁴ -14.80585682 XP ⁵ +20.84349277 XP ⁶ -14.93098343 XP ⁷ +3.81129322 XP ⁸ (Equation 6) DX (P) 8% = +1.07146979 +1.31854258 XP ¹ +2.09508243 XP ² -1.56431680 XP ³ +9.77390941 XP ⁴ -20.78031239 XP ⁵ +29.09490800 XP ⁶ -20.67590885 XP ⁷ +5.23764237 XP ⁸ (Equation 7) ) DX (P) 10% = + 1.34291141 +1.65520395 XP ¹ +2.61986590 XP ² -1.82253414 XP ³ +11.75807209 XP ⁴ -24.96132430 XP ⁵ +35.19648020 XP ⁶ -25.05597865 XP ⁷ +6.30131364 XP ⁸ (Equation 8) DX ( P) 12% = + 1.61582788 +1.99351126 XP ¹ +3.17433403 XP ² -2.26391522 XP ³ +14.508958 46 XP ⁴ -30.80026724 XP ⁵ +43.29761155 XP ⁶ -30.63836121 XP ⁷ +7.64115670 XP ⁸・ ・ ・ (Formula 9) DX (P) 14% = + 1.89024313 +2.33414370 XP ¹ +3.74147069 XP ² -2.72187655 XP ³ +17.27931001 XP ⁴ -36.54042195 XP ⁵ +51.17201688 XP ⁶ -35.97796660 XP ⁷ +8.88072818 XP ⁸ (Equation 10) DX (P) 16% = + 2.16618179 +2.67732909 XP ¹ +4.32082782 XP ² -3.21926933 XP ³ +20.25345514 XP ⁴ -42.72852909 XP ⁵ +59.60153297 XP ⁶ -41.60998791 XP ⁷ +10.16129479 XP ⁸ (Equation 11) DX (P) 18% = + 2.44364238 +3.02331333 XP ¹ +4.91623288 XP ² -3.79767931 XP ³ +23.59936156 XP ⁴ -49.69076375 XP ⁵ +68.91243507 XP ⁶ -47.68527323 XP ⁷ +11.50586163 XP ⁸ (Equation 12) DX (P) 20% = + 2.72266561 +3.37173787 XP ¹ +5.53609305 XP ² -4.52367539 XP ³ +27.58254514 XP ⁴ -57.98461819 XP ⁵ +79.73752518 XP ^6- 54.56195224 XP ⁷ +12.99326168 XP ⁸ (Equation 13) Incidentally, the change of the shooting distance with respect to DX (P) represented by Equations 3 to 13 is roughly as shown in Table 1 below in this embodiment.

[0037]

[Table 1] FIG. 10 shows a wide end of an image magnification setting cam 13g provided on the small diameter portion 13b of the cam barrel 13 and an image magnification setting cam 13 of the same size.
FIG. 11 is a detailed view of the state of the telephoto end of g ′ and the surroundings of the image magnification setting communication tube 8 related thereto, and an arrow A shown in FIG. 10 indicates that the image magnification setting is from zero (infinity) to MAX (closest). The transition of the image magnification setting communication tube 8 is shown. Further, an arrow B shows the transition from the wide end of the previous zoom to the tele end, and this arrow B shows the cam barrel 1
3 is equal to the fixed pin cam 13c provided on the large diameter portion 13a.

In FIG. 10, the length of Z6 is the zoom movement amount of the sixth lens unit in the infinite state, θ is the image magnification setting rotation angle from the image magnification setting infinity, and FX (wide, θ) is F (θ). Set the image magnification setting movement amount at the wide end, FX (Tele, θ) is F
The image magnification setting movement amount at the telephoto end in (θ), point A is the origin when the cam shape is represented.

As is clear from FIG. 10, as the zoom gets closer to the telephoto end, the extension amount DX of the sixth lens group shown in FIG. 8 is seen.
It can be seen that the image magnification setting movement amount FX correspondingly increases.

[Description of Image Magnification Setting Cam Shape] In FIG. 10, point A corresponds to the image magnification setting infinite position at the wide end, and this is the origin. From this point A, consider a parameter P that is positive in the right direction in the figure, and set P = 1 to the abscissa of the infinite position at the tele end. When a positive value is given in the direction in which the light from point A passes (downward in the figure) and the ordinate of the cam is DF (P), the cam shape of the image magnification setting cam 13g is DF ( P) = +1.56131534 XP ¹ 3.39435931 XP ² -6.95936861 XP ³ 11.31699826 XP ⁴ -6.68253907 XP ⁵ 1.56674217 XP ⁶ 2.41896439 XP ⁷ -0.90631859 XP ⁸ 1.44960459 XP ⁹ ... (Equation 14)

[Explanation of Zoom Operation] Next, in the above configuration, when a drive signal is input to the zoom drive unit 11 for zooming and the first group lens barrel 9 is extended from the wide end to the tele end, the cam barrel is moved. Numeral 13 carries out rotation feeding. Then, due to the rotational extension of the cam ring 13, the fifth-group barrel 15
Moves straight, and at the same time, the third group lens barrel 17 and the fourth group lens barrel 18 also move straight.

On the other hand, in the state where the image magnification setting is fixed as described above, the sixth group lens barrel 19 is restricted in its rotation by the vertical groove 8b of the image magnification setting communication tube 8 connected to the image magnification setting key 7, and therefore goes straight. Move.

[Description of Image Magnification Setting Operation] The image magnification setting rotation angle θ has a positive value in this embodiment (this is called a wide start cam). The amount of extension of the image magnification setting rotation angle θ at the zoom amount P is (P
It suffices to find how much the cam coordinate DF (P + θ) at + θ) has changed from the cam coordinate DF (P) at (P). Therefore, if the feed amount is set as DF (P, θ), it is represented by DF (P, θ) = DF (P + θ) −DF (P).

Here, for example, P = 1, that is, at the telephoto end, the payout amount DX (1) x% and DF (1,0) do not become the same at a certain photographing image magnification (probably x%). For example, focusing is performed at the telephoto end, and the image magnification x% is set. Zooming is performed from P = 1 to P = 0 without changing θ (in other words, fixing the image magnification setting). When changing, the cam deviation amount ΔDX (P) x% is represented by ΔDX (P) = DF (P, θ) -DX (1) x% (Equation 15), and ΔDX (P) is It is the image magnification setting cam 13g in FIG. 10 shown in Expression 14 that is set so as to always be 0 (between P = 0 and P = 1).

FIG. 11 is a diagram showing the state of the image magnification and the photographing distance in the above configuration, in which the zoom parameter is set in the upper direction of the vertical axis and the image magnification setting angle θ is set in the left direction of the horizontal axis. .

In FIG. 11, the line representing the image magnification is a substantially vertical line, and if the image magnification setting angle θ is set, the image magnification hardly changes due to zooming. At the same time, the lines of equal shooting distance, which are represented by broken lines, are inclined,
It is possible to respond to changes in the shooting distance without changing the image magnification during zooming operation.

From these facts, it can be seen that the work called the conventional zooming operation in the present invention actually has the function of the focusing operation after setting the magnification.

On the other hand, when the zooming is fixed (the focal length is set) and the image magnification setting angle is adjusted, the focusing function can be realized and the conventional zoom lens can be used. Note that the photographable distance range corresponding to each set image magnification is shown in Table 1 above.

FIG. 12 is a diagram showing the state of the image magnification and the photographing distance in the conventional example, which was created using the same optical system data as in the first embodiment. As is clear from the figure, the change in the photographing distance is shown. In order to achieve a constant image magnification according to the above, it is necessary to change the zoom parameter and the focus rotation angle at the same time.

Example 2. 13 to 14 show a second embodiment of the present invention, in which the autofocus control is added to the first embodiment.

"Explanation of control block of lens system" FIG.
Indicates the relationship among the zoom drive unit 11, the image magnification setting unit 6, the zoom encoder 21, the image magnification encoder 22, the drive circuit 23, the focus determination unit 24, and the control unit 25. It is a control block diagram of a lens system.

The zoom drive unit 11 performs the zooming operation of the lens by the signal from the drive circuit 23 as described in the first embodiment. Further, the image magnification setting unit 6 also sets the image magnification of the lens by the signal from the drive circuit 23 as described in the first embodiment.

The zooming encoder 21 can detect the zoom parameter Zp and transmits a detection signal to the control unit 25. The image magnification encoder 22 can detect the image magnification setting angle θ, and transmits a detection signal to the control unit 25.

The drive circuit 23 receives the control signal from the control section 25 and drives the zoom drive unit 11 and the image magnification setting unit 6 described above. The focus determination unit 24 transmits a state signal of image formation by the lens system to the control unit 25. The control unit 25 processes the signals from the zooming encoder 21, the image magnification encoder 22, and the focus determination unit 24, and drives the zoom drive unit 11 and the image magnification setting unit 6 as described above.

[Explanation of Control Flow of Lens System] FIG. 14 shows a control flow of the lens system constituted by the control blocks shown in FIG.

After the control is started, the image magnification setting value (hereinafter referred to as the setting value) = β ₀ is confirmed in step ST14-1, and the AF focus detection is determined in step ST14-2.
If it is OK, it means that the focus is set to the desired setting value β ₀ ,
The operation ends in step ST14-3. However, in the case of in-focus NG, both the front pin and the rear pin can perform control in substantially the same pattern. Therefore, the description here will be focused on the case of the rear pin being NG.

When the rear pin is NG, the tele side is the in-focus direction, so the tele end is determined in step ST14-4, and if it is not the end, there is a possibility of movement, so zooming in step ST14-5. Calculate the amount, then step S
At T14-6, it is judged whether or not the zoom movement amount exceeds the tele end, and if not, the zoom movement is performed to the tele end at step ST14-7, and the first AF focus detection focusing at step ST14-2 for confirmation. Returning to the determination flow, in this process, the change in image magnification does not occur within the design error range, as is apparent from FIG.

If it is determined in step ST14-6 that the zoom movement amount is likely to exceed the telephoto end, the zoom drive is performed to the telephoto end in step ST14-8, and the AF is confirmed in step ST14-9 for confirmation. The focus determination for distance measurement is performed. If in focus, the process proceeds to step ST14-10 to end the operation. In the case of NG, the zoom drive is given up and the control is changed to the image magnification setting drive.

From this step onward, step ST14-2
At the time of the first AF distance measurement focusing determination, the flow merges and enters the same flow as when the zoom position is at the tele end with the rear pin.

Since focus control is performed by driving the image magnification, the process proceeds to step ST14-11 to calculate how much the image magnification should be changed to achieve the focus, and the calculated image magnification is set to β. At step ST14-12, the image magnification β
Is determined to be the image magnification β calculated by confirming that is smaller than the set value β ₀ described above, step ST14-13.
In step ST14-9, the image magnification changing drive is performed.
F Check the focus determination for distance measurement.

However, if the image magnification β does not become smaller than the set value β ₀ , it means that the initial set value β ₀ can be secured because it is at the tele end now, and step ST14-1
After driving the image magnification β so as to be equal to the set value β ₀ in step 4, the process returns to the first AF distance measurement focusing determination confirmation flow performed in step ST14-2.

In the case of the rear pin NG described here, since the lens system covers the infinite distance as is apparent from FIG. 11, the in-focus point can always be reached, but
In the first AF distance measurement focus determination confirmation flow, the front pin N
In the case of G, the subject may be too close to focus, so steps ST14-15 to ST14-27.
In the processing in the case of the front pin NG performed in step 1, it is determined whether or not the maximum edge of the image magnification is reached when driving the image magnification in an area where the image magnification β must be larger than the set value β _0. Only the flow is
-3 to ST14-14, which is different from the processing in the case of the rear pin NG.

In the second embodiment, focusing can be achieved by AF with only one drive, and focusing can be supplemented with AF with only one drive that varies the image magnification β even in an area outside the set value β _0. As for tracking a moving subject, it is very convenient and controllable.

[0064]

As described above, according to the present invention,
A configuration including an image magnification setting unit that enables a focusing operation, and a focusing unit based on a mechanism that realizes a relationship between a focal length and a subject distance that maintains a specific image magnification set by the image magnification setting unit. Therefore, it is possible to focus manually with a fixed magnification for a moving subject.
In the combination of F drive, a simple control method
Advanced subject tracking is possible.

Further, the present invention can be applied to a conventional zoom lens, that is, a so-called front-lens focus zoom lens without any hindrance, and if it is applied to a zoom lens which is used for a projector or the like in which the magnification is determined, the zoom lens can be used. It has the effect of significantly improving operability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a telephoto end state of a lens of Example 1 of the present invention.

FIG. 2 is a cross-sectional view showing a wide-end state of the lens of Example 1 of the present invention.

FIG. 3 is a development view of the cam barrel according to the first embodiment of the present invention.

FIG. 4 is a development view of the fixed barrel according to the first embodiment of the present invention.

FIG. 5 is a development view of the fitting portion of the fifth group lens barrel according to the first embodiment of the present invention.

FIG. 6 is a development view of the first group lens barrel of Embodiment 1 of the present invention.

FIG. 7 is a development view of the image magnification setting connecting cylinder according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a moving amount of an image magnification setting group according to the first embodiment of the present invention.

FIG. 9 is a zoom movement diagram in zooming of each zoom group according to the first embodiment of the present invention.

FIG. 10 is a detailed diagram around the image magnification setting cam according to the first embodiment of the present invention.

FIG. 11 is a diagram showing a state of image magnification and shooting distance according to the first embodiment of the present invention.

FIG. 12 is a diagram showing a state of image magnification and shooting distance in a conventional example.

FIG. 13 is a control block diagram of a lens system according to a second embodiment of the present invention.

FIG. 14 is a control flowchart of the lens system according to the second embodiment of the present invention.

[Explanation of symbols]

 1 Fixed Tube 5 Rotating Tube 6 Image Magnification Setting Unit 7 Image Magnification Setting Key 8 Image Magnification Setting Communication Tube 9 1st Group Lens Tube 10 Zoom Ring 11 Zoom Drive Unit 13 Cam Tube 14 2nd Group Lens Tube 15 5th Group Lens Tube 17 3rd Group Lens barrel 18 4th lens barrel 19 6th lens barrel

Claims (1)

[Claims] 1. An image magnification setting means capable of performing a focusing operation, and a focusing means for realizing a relationship between a focal length and a subject distance for maintaining a specific image magnification set by the image magnification setting means. A zoom lens equipped with.