JP4815973B2 - Electronic camera - Google Patents

Description

  The present invention relates to an electronic camera incorporating a zoom lens.

As a lens having a high zoom ratio that can be mounted on an electronic camera, a so-called positive refractive power preceding zoom lens having at least three lens groups of a positive refractive power lens group, a negative refractive power lens group, and a positive refractive power lens group Is known (see, for example, Patent Document 1 and Patent Document 2).
JP-A-8-43733 Japanese Laid-Open Patent Publication No. 8-94933

  However, a zoom lens in which the first lens unit having positive refractive power is fixed during zooming as disclosed in Patent Document 1 has a large front lens diameter when attempting to widen the angle of view in the wide-angle end state. It is difficult to make the electronic camera small.

  In addition, the zoom lens in which the first lens unit having positive refractive power moves to the subject side during zooming as disclosed in Patent Document 2 has a large front lens diameter even when the angle of view in the wide-angle end state is widened. This zoom lens is suitable for increasing the zoom ratio while widening the angle of view in the wide-angle end state. However, in the intermediate focal length state, the chief ray that passes through the first lens group is farthest from the optical axis. Due to its nature, it is inevitable that the front lens diameter will increase when the zoom ratio in the intermediate focal length state is increased.

  The present invention has been made in view of the above-described problems, and is a miniaturization in which the front lens diameter is kept small while maintaining a high zoom ratio in a wide angle of view of 60 degrees or more in the wide-angle end state and an intermediate focal length state. An object is to provide an electronic camera.

In order to solve the above problems, the present invention includes, in order from the object scene side, comprises a first lens unit having a positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, A zoom lens that varies a focal length by moving the first lens group and the third lens group toward the subject, a detection unit that detects a position of the third lens group from the first lens group, and An imaging unit that converts an object image formed by the zoom lens into an electrical signal, an image generation unit that generates an image from the signal of the imaging unit, and an electronic zoom magnification of an arbitrary part of the image formed by the image generation unit And an electronic zoom magnification is set to 1 in a wide-angle end state and a telephoto end state of the zoom lens, and the electronic zoom unit is responsive to a signal from the detection unit. Changing the magnification, the moving distance of the first lens group from the wide-angle end state of the zoom lens to the telephoto end state .DELTA.1, the focal length of the first lens group when the f1,
0.1 <Δ1 / f1 <0.6
An electronic camera characterized by satisfying the above is provided.

  According to the present invention, it is possible to provide a miniaturized electronic camera in which the front lens diameter is kept small while maintaining a high zoom ratio in a wide angle of view of 60 degrees or more in the wide-angle end state and an intermediate focal length state.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of an electronic camera according to an embodiment of the present invention.

  In FIG. 1, a photographic lens 11 receives light from a subject (not shown) and forms a real image on the image sensor 13. The low-pass filter 12 disposed on the optical path between the photographic lens 11 and the image sensor 13 cuts a light beam having a spatial frequency higher than the limit resolution of the image sensor 13 or a wavelength other than visible light. The plurality of lens groups 11 a, 11 b, and 11 c constituting the photographing lens 11 are configured to be movable on the optical axis by the zoom drive motor 14 and the drive device 15. In FIG. 1, the driving device 15 describes a cam structure having cam grooves 15a, 15b, and 15c corresponding to the plurality of lens groups 11a, 11b, and 11c. It is also possible to use other methods such as moving with independent zoom drive motors 14.

  The subject image is converted into an electrical signal by the image sensor 13 and becomes an electronic image through the image generation unit 16. On the other hand, a lens position detection device 17 is connected to the driving device 15. The lens position detection device 17 detects the zoom state of the photographic lens 11, and this signal is input to the electronic zoom magnification calculator 18. The electronic zoom magnification calculator 18 obtains an electronic zoom magnification according to the zoom state of the photographing lens 11.

  The electronic zoom processing unit 19 cuts out a part of the image generated by the image generation unit 16 and generates a new image based on the electronic zoom magnification obtained by the electronic zoom magnification calculation unit 18. This image is sent to the display generation unit 21 and displayed on the display monitor 22, while an electronic image of the subject is recorded in the recording device 24 through the recording generation unit 23.

  The effective focal length calculation unit 20 calculates an effective focal length converted from the angle of view of the photographing lens 11 based on signals from the lens position detection device 17 and the electronic zoom magnification calculation unit 18. This effective focal length can be calculated by (focal length of taking lens 11) × (electronic zoom magnification). A table in which an effective focal length corresponding to the position of the photographing lens 11 is calculated in advance may be stored in a memory (not shown) of the electronic camera 10 and used as appropriate.

  The effective focal length calculated by the effective focal length calculation unit 20 is sent to the display generation unit 21 and the recording generation unit 23 and is recorded on the recording device 24 when displayed on the display monitor 22 together with the subject image. Thus, the electronic camera 10 according to the present embodiment is configured.

  The electronic camera 10 according to the present embodiment generates a zoomed image based on the electronic zoom magnification of the electronic zoom magnification calculator 18 by cutting out a part of the image by the electronic zoom processor 19 according to the zoom state of the photographing lens 11. By doing so, the photographic lens 11 is reduced in size.

  A photographing lens (hereinafter referred to as a zoom lens) 11 mounted on the electronic camera 10 according to the present embodiment includes, in order from the subject, a first lens group having a positive refractive power, a second lens group having a negative refractive power, A third lens group having a positive refractive power is provided, and the focal length is changed by moving the first lens group and the third lens group to the subject side.

  This type of zoom lens 11 has the property that the principal ray passing through the first lens group is farthest from the optical axis in the intermediate focal length state between the wide-angle end state and the telephoto end state. By reducing the height, an increase in front lens diameter was suppressed, and the zoom lens 11 and thus the entire electronic camera 10 were reduced in size. The image height in the intermediate focal length state is determined so that the front lens diameter is determined based on the height of the principal ray passing through the first lens group in the wide-angle end state, and the light beam does not vignett at the front lens diameter.

In the electronic camera 10 according to the present invention, when the movement amount of the first lens group from the wide-angle end state to the telephoto end state of the zoom lens 11 is Δ1, and the focal length of the first lens group is f1, the following conditions are satisfied. It is desirable to satisfy formula (1).
(1) 0.1 <Δ1 / f1 <0.6
If the lower limit of conditional expression (1) is exceeded, the amount of movement of the first lens group is too small, so that when the zoom lens 11 is widened, the front lens diameter increases or a high zoom ratio cannot be obtained. Or spherical aberration and coma aberration deteriorate. If the upper limit value of conditional expression (1) is exceeded, the amount of movement of the first lens group is too large, leading to an increase in size of the zoom lens 11 in the telephoto end state. Or, astigmatism deteriorates.

  Further, in the electronic camera 10 according to the present embodiment, the electronic zoom magnification is set to a magnification exceeding 1 × in the wide-angle end state and exceeding 1 × in the intermediate focal length state. However, the electronic zoom generally deteriorates the image quality. It is desirable to use at a magnification as small as possible, and it is desirable to use 1 × in the telephoto end state. Even in the intermediate focal length state, it is desirable that the electronic zoom magnification does not exceed 1.4 times at the maximum.

  Further, like the electronic camera 10 according to the present embodiment, in the electronic camera 10 using both the optical zoom based on the movement of the zoom lens 11 and the electronic zoom, the focal length of the optical zoom is displayed for the user. Inconvenient. Therefore, in the electronic camera 10 according to the present embodiment, the effective focal length calculation unit 20 converts the effective focal length converted from the angle of view of the photographing lens 11 based on the signals from the lens position detection device 17 and the electronic zoom magnification calculation unit 18. Is calculated. This effective focal length may be calculated by (focal length of the photographing lens 11) × (electronic zoom magnification) or may be obtained from a table stored in a memory (not shown) of the electronic camera 10. good.

  The effective focal length obtained by the effective focal length calculator 20 is sent to the display generator 21 and displayed on the display monitor 22 together with the subject image. FIG. 2 is a display example on the display monitor 22. 2A is an example in which the effective focal length is displayed on the screen as it is, and FIG. 2B is an example in which the effective focal length is displayed as a bar graph.

  In recent digital cameras, information such as the shooting date, shutter speed, and aperture value can be recorded in the recording device 24 together with image information. Also in this case, it is desirable that the recorded focal length is not the focal length of the photographing lens 11 but the effective focal length. The electronic camera 10 according to the present embodiment is configured such that a signal from the effective focal length calculation unit 20 is sent to the recording generation unit 23 and recorded in the recording device 24 together with the captured image.

"Example"
Next, the zoom lens 11 mounted on the electronic camera 10 according to the embodiment of the present invention will be specifically described based on the following examples.

“First Example”
FIG. 3 shows a zoom lens lens configuration diagram according to the first embodiment of the present invention. In FIG. 3, the zoom lens according to the first example includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a first lens group G3 having a positive refractive power. The first lens group G1 and the third lens group G3 are moved toward the object side during zooming from the wide-angle end state W to the telephoto end state T, and the second lens group G2 is in the intermediate focal length state M3. From the intermediate focal length state M3 to the telephoto end state T, the fourth lens group G4 takes a convex U-turn trajectory on the image plane I side, and has a zoom ratio of 7 This is a zoom lens with a 4 × group configuration of 6 ×.

  The aperture stop S is disposed on the object side of the third lens group G3 and moves integrally with the third lens group G3. Between the fourth lens group G4 and the image plane I, a low-pass filter P1 for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state image sensor and a cover glass P2 for protecting the solid-state image sensor are arranged. It is installed. Further, focusing can be performed by the fourth lens group G4 or the entire extension. Further, as shown in FIG. 4, the effective diameter of the front lens is suppressed to be as small as 18.8 mm by performing electronic zoom up to 1.27 times in the intermediate focal length state M2.

Table 1 below shows values of specifications of the zoom lens according to the first example. In Table 1, f in (Overall specifications) is focal length, Bf is back focus, FNo is F number, 2A is angle of view (unit: degree), and y is image height. The number in the first column in (lens data) is the lens surface number from the object, r is the radius of curvature, d is the surface spacing, νd and nd are the Abbe number and refractive index for the d line (λ = 587.6 nm). Note that r = ∞ represents a plane. The aspherical surface in the (aspherical surface data) indicates that the depth of the surface in the optical axis direction is x, the height in the direction perpendicular to the optical axis is h, the radius of curvature (paraxial radius of curvature) of the reference spherical surface is r, and the cone coefficient is K. The nth-order aspherical coefficient is represented by the following equation, where Cn is represented by the following formula, and is marked with an asterisk (*) in the left column of the lens surface number. “E-n” indicates “10 ⁻ⁿ ”.
X = (h ² / r) / (1 + K × h ² / r ² ) ^1/2 )
+ C4 × h ⁴ + C6 × h ⁶ + C8 × h ⁸ + C10 × h ¹⁰
In (variable interval data), f is the focal length, y is the image height, Bf is the back focus, Z1 is the optical zoom magnification, Z2 is the electronic zoom magnification, and Z0 is the effective zoom magnification.

  In all the following specification values, “mm” is generally used as the focal length f, radius of curvature r, surface interval d and other lengths, etc. unless otherwise specified, but the optical system is proportional. Even if it is enlarged or proportionally reduced, the same optical performance can be obtained. Further, the unit is not limited to “mm”, and other appropriate units may be used. Further, the explanation of these symbols is the same in the other embodiments, and the explanation is omitted.

(Table 1)
(Overall specifications)
f = 6.30-47.9
Bf = 0.59
FNo = 2.77-4.62
2A = 64.03-8.68
y = 3.75

(Lens data)
rd νd nd
1) 34.1194 0.9500 27.51 1.755200
2) 21.3330 4.0000 81.61 1.497000
3) -84.5256 0.1000 1.000000
4) 27.3623 1.4000 46.58 1.804000
5) 39.1831 (D1) 1.000000
6) -198.4493 0.8000 46.63 1.816000
7) 6.0301 2.3000 1.000000
8) -17.2496 0.8000 54.66 1.729160
9) 23.9597 0.1000 1.000000
10) 12.3105 1.7000 23.78 1.846660
11) -133.3487 (D2) 1.000000
12> ∞ 0.4000 1.000000 Aperture stop S
* 13) 6.1467 2.5000 63.05 1.514500
* 14) -17.8808 0.1000 1.000000
15) 6.6043 2.4000 81.61 1.497000
16) -12.2878 0.8000 34.96 1.801000
17) 4.4511 0.8000 1.000000
18) 16.5500 1.3000 43.69 1.720000
19) -107.2453 (D3) 1.000000
20) 65.8729 1.8000 42.72 1.834810
21) -33.8068 (D4) 1.000000
22) ∞ 1.5600 64.14 1.516330
23) ∞ 0.4593 1.000000
24) ∞ 0.5000 64.14 1.516330
25) ∞ (Bf) 1.000000

(Aspherical data)
Face KC 4 C 6 C 8 C10
13 0.3663 1.00000E-10 2.67410E-06 -8.00590E-09 1.00000E-16
14 -5.7160 1.00000E-10 3.14720E-06 -7.15130E-08 1.00000E-16

(Variable interval data)
W M1 M2 M3 T
f 6.30226 12.00701 16.50019 25.02178 47.90000
y 3.75000 3.20000 2.95000 3.00000 3.75000
D1 1.40360 8.60436 12.45879 16.45126 20.43742
D2 15.36628 10.78789 8.85743 6.15306 1.61058
D3 4.88271 9.54470 10.71838 12.17576 15.95384
D4 2.57702 1.11539 1.16328 1.58689 2.40051
Bf 0.59000 0.59000 0.59000 0.59000 0.59000
Z1 1.00000 1.90520 2.61810 3.97030 7.60040
Z2 1.00000 1.17190 1.27120 1.25000 1.00000
Z0 1.00000 2.23260 3.32810 4.96290 7.60040

(Conditional numerical values)
Δ1 / f1 = 0.405
Maximum electronic zoom magnification = 1.271

  FIG. 4 is a graph showing the relationship between the focal length of the zoom lens according to the first embodiment and the zoom magnification for each of the optical zoom magnification, the electronic zoom magnification of the electronic camera, and the effective zoom magnification of the electronic camera.

  It can be seen that the electronic camera using the zoom lens according to the first embodiment can obtain a higher overall zoom magnification in the intermediate focal length state than in the case of only the optical zoom.

  FIG. 5 shows various aberration diagrams of the zoom lens according to the first example at the time of focusing on infinity. (A) shows the wide-angle end state W, (b) shows the intermediate focal length state M2, and (c). Shows various aberration diagrams in the telephoto end state T, respectively.

  In each aberration diagram, FNO is the F number, Y is the image height, C is the C line (λ = 656.3 nm), d is the d line (λ = 587.6 nm), and F is the F line (λ = 486.1 nm). , G respectively show aberration curves of the g-line (λ = 435.8 nm). The spherical aberration diagram shows the F-number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum value of the image height Y, and the coma diagram shows the value of each image height Y. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that. In the aberration diagrams of other examples below, the same reference numerals as those of the first example are used, and description thereof is omitted.

  From the respective aberration diagrams, the zoom lens according to the first example has various image aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging characteristics. It can be seen that the zoom lens has a high effective zoom magnification.

"Second Example"
FIG. 6 shows a zoom lens configuration diagram according to the second embodiment of the present invention. In FIG. 6, the zoom lens according to the second example includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a first lens group having a positive refractive power. The fourth lens group G4 includes a fifth lens group G5 having a positive refractive power. During zooming from the wide-angle end state W to the telephoto end state T, the first lens group G1, the third lens group G3, and the fourth lens group G4 are objects. The second lens group G2 moves to the image plane I side to the intermediate focal length state M4, moves to the object side from the intermediate focal length state M4 to the telephoto end state T, and the fifth lens group G5 This is a zoom lens having a five-group configuration with a zoom ratio of 9.6 times fixed during zooming.

  The aperture stop S is disposed in the third lens group G3 and moves integrally with the third lens group G3. Between the fifth lens group G5 and the image plane I, a low-pass filter P1 for cutting a spatial frequency higher than the limit resolution of the solid-state image sensor and a cover glass P2 for protecting the solid-state image sensor are arranged. It is installed. Further, focusing can be performed by the fifth lens group G5 or the entire extension. Further, as shown in FIG. 7, the effective diameter of the front lens is suppressed to be as small as 23.2 mm by performing electronic zoom up to 1.27 times in the intermediate focal length state M1.

  Table 2 below shows values of specifications of the zoom lens according to the second example.

(Table 2)
(Overall specifications)
f = 6.28-60.6
Bf = 0.59
FNo = 2.62-5.09
2A = 62.85-7.06
y = 3.75

(Lens data)
rd νd nd
1) 34.3306 1.2000 32.35 1.850260
2) 19.7969 4.2000 82.52 1.497820
3) 98.5405 0.1000 1.000000
4) 23.3797 3.0000 60.29 1.620410
5) 186.3206 (D1) 1.000000
6) 131.8660 1.3000 49.23 1.743300
* 7) 5.5822 3.8000 1.000000
8) -9.5986 0.9000 61.18 1.589130
9) 2943.6842 0.7000 1.000000
10) 31.6381 1.9000 23.78 1.846660
11) -35.1993 (D2) 1.000000
12) 11.7662 0.8000 32.35 1.850 260
13) 8.7019 2.0000 82.52 1.497820
14) -62.6148 0.6000 1.000000
15> ∞ 0.6000 1.000000 Aperture stop S
16) 13.4720 2.8000 43.73 1.605620
17) -9.1916 1.5000 40.11 1.762000
18) 18.7567 (D3) 1.000000
* 19) 15.6020 2.3000 45.37 1.796681
20) -16.4730 0.1000 1.000000
21) 26.3399 2.8000 82.52 1.497820
22) -7.3577 1.0000 37.17 1.834000
23) 11.8834 (D4) 1.000000
24) 10.0000 2.1000 70.24 1.487490
25) 33.9961 (D5) 1.000000
26) ∞ 1.5600 64.20 1.516800
27) ∞ 0.5000 1.000000
28) ∞ 0.5000 64.20 1.516800
29) ∞ (Bf) 1.000000

(Aspherical data)
Face KC 4 C 6 C 8 C10
7 0.6005 0.00000E + 00 -3.59910E-06 1.55570E-07 -1.13010E-09
19 -0.9824 0.00000E + 00 3.41390E-07 2.81080E-08 -2.90270E-10

(Variable interval data)
W M1 M2 M3 M4 T
f 6.28000 10.00000 16.00000 25.00000 40.00000 60.40000
y 3.75000 3.18000 3.16000 3.35000 3.57000 3.75000
D1 1.39051 7.15787 11.75181 15.34490 18.68657 20.14272
D2 19.77618 14.82120 10.66398 7.25791 3.90061 0.80133
D3 4.84043 3.66072 2.75180 2.20755 2.09129 2.23033
D4 4.18270 6.82486 9.97207 13.35789 16.81568 22.92347
D5 2.53179 2.53179 2.53179 2.53179 2.53179 2.53179
Bf 0.59000 0.59000 0.59000 0.59000 0.59000 0.59000
Z1 1.00000 1.59240 2.54780 3.98090 6.36940 9.61780
Z2 1.00000 1.17920 1.18670 1.11940 1.05040 1.00000
Z0 1.00000 1.87780 3.02350 4.45620 6.69060 9.61780

(Conditional numerical values)
Δ1 / f1 = 0.396
Maximum electronic zoom magnification = 1.187

  FIG. 7 is a graph showing the relationship between the focal length and zoom magnification of the zoom lens according to the second embodiment for each of the optical zoom magnification, the electronic zoom magnification of the electronic camera, and the effective zoom magnification of the electronic camera.

  It can be seen that the electronic camera using the zoom lens according to the second embodiment can obtain a higher overall zoom magnification in the intermediate focal length state than in the case of only the optical zoom.

  8A and 8B show various aberration diagrams of the zoom lens according to the second example at the time of focusing on infinity. FIG. 8A shows the wide-angle end state W, FIG. 8B shows the intermediate focal length state M2, and FIG. Shows various aberration diagrams in the telephoto end state T, respectively.

  From each aberration diagram, the zoom lens according to the second example has various aberrations corrected well from the wide-angle end state to the telephoto end state, and has excellent imaging characteristics. It can be seen that the zoom lens has a high effective zoom magnification.

“Third Example”
FIG. 9 shows a zoom lens arrangement according to the third embodiment of the present invention. In FIG. 9, the zoom lens according to the third example includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a first lens group G3 having a positive refractive power. The first lens group G1 and the third lens group G3 are moved toward the object side during zooming from the wide-angle end state W to the telephoto end state T, and the second lens group G2 is in the intermediate focal length state M3. From the intermediate focal length state M3 to the telephoto end state T to the object side, and the fourth lens group G4 is a four-group configuration with a zoom ratio of 4.05 times fixed during zooming. This is a zoom lens.

  The aperture stop S is disposed on the object side of the third lens group G3 and moves integrally with the third lens group G3. Between the fourth lens group G4 and the image plane I, a low-pass filter P1 for cutting a spatial frequency equal to or higher than the limit resolution of the solid-state image sensor and a cover glass P2 for protecting the solid-state image sensor are arranged. It is installed. Further, focusing can be performed by the fourth lens group G4 or the entire extension. Further, as shown in FIG. 10, the effective diameter of the front lens is suppressed to be as small as 17.5 mm by performing electronic zoom up to 1.27 times in the intermediate focal length state M2.

  Table 3 below shows values of specifications of the zoom lens according to the third example.

(Table 3)
(Overall specifications)
f = 4.82-19.5
Bf = 0.59
FNo = 2.85-4.86
2A = 78.82-21.11
y = 3.75

(Lens data)
rd νd nd
1) 34.1753 1.0000 23.78 1.846660
2) 21.4069 2.7000 52.32 1.755000
3) -479.6864 (D1) 1.000000
4) 70.0000 1.1000 45.45 1.750390
* 5) 5.7403 2.0000 1.000000
6) -96.6750 0.8000 49.61 1.772500
7) 7.3123 1.0000 1.000000
8) 9.2228 1.7000 23.78 1.846660
9) 96.6023 (D2) 1.000000
10> ∞ 0.8000 1.000000 Aperture stop S
* 11) 12.0366 1.4000 57.44 1.606020
12) -15.9911 0.1000 1.000000
13) 4.5553 2.0000 50.80 1.570990
14) 20.7741 0.8000 23.78 1.846660
15) 3.8245 0.8000 1.000000
16) -17.3761 1.1000 56.32 1.568830
17) -8.1219 (D3) 1.000000
18) 8.8508 2.3000 81.61 1.497000
19) -400.8130 (D4) 1.000000
20) ∞ 1.5600 64.14 1.516330
21) ∞ 0.5000 1.000000
22) ∞ 0.5000 64.14 1.516330
23) ∞ (Bf) 1.000000

(Aspherical data)
Face KC 4 C 6 C 8 C10
5 0.6601 0.00000E + 00 0.00000E + 00 7.82550E-09 0.00000E + 00
11 -3.5496 0.00000E + 00 -7.56840E-06 0.00000E + 00 0.00000E + 00

(Variable interval data)
W M1 M2 M3 T
f 4.82000 6.80000 9.60000 13.60000 19.50000
y 3.75000 3.30000 3.20000 3.55000 3.75000
D1 0.70019 4.76805 8.55861 11.31386 13.58393
D2 10.29742 7.47775 5.19046 3.12801 1.34331
D3 3.79574 5.66803 7.92293 11.11479 15.58464
D4 1.81068 1.81068 1.81068 1.81068 1.81068
Bf 0.59000 0.58999 0.59000 0.59000 0.58999
Z1 1.00000 1.41080 1.99170 2.82160 4.04560
Z2 1.00000 1.13640 1.17190 1.05630 1.00000
Z0 1.00000 1.60320 2.33400 2.98050 4.04560

(Conditional numerical values)
Δ1 / f1 = 0.347
Maximum electronic zoom magnification = 1.172

  FIG. 10 is a graph showing the relationship between the focal length and the zoom magnification of the zoom lens according to the third embodiment for each of the optical zoom magnification, the electronic zoom magnification of the electronic camera, and the effective zoom magnification of the electronic camera.

  It can be seen that the electronic camera using the zoom lens according to the third embodiment can obtain a higher overall zoom magnification in the intermediate focal length state than in the case of only the optical zoom.

  FIG. 11 shows various aberration diagrams of the zoom lens according to the third example at the time of focusing on infinity, (a) shows the wide-angle end state W, (b) shows the intermediate focal length state M2, and (c). Shows various aberration diagrams in the telephoto end state T, respectively.

  From each aberration diagram, the zoom lens according to the third example has various image aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging characteristics. It can be seen that the zoom lens has a high effective zoom magnification.

  In addition, although the lens system of 4 group and 5 group structure was shown as an Example of this invention, the lens system which added only the additional lens group to this 4 group or 5 group is equivalent, and the effect of this invention was inherent. Needless to say, it is a lens system. In addition, in the configuration within each lens group, it goes without saying that a lens group in which an additional lens is added to the configuration of the embodiment is an equivalent lens group in which the effects of the present invention are inherent.

  Thus, according to the present invention, a small electronic camera can be obtained while having a high zoom magnification. The above-described embodiment is merely an example, and is not limited to the above-described configuration and shape, and can be appropriately modified and changed within the scope of the present invention.

It is a schematic diagram of the electronic camera concerning embodiment of this invention. It is a display example on a display monitor, (a) is an example in which the effective focal length is displayed as it is on the screen, and (b) is an example in which the effective focal length is displayed as a bar graph. 1 is a configuration diagram of a zoom lens lens according to a first example of the present invention. FIG. 6 is a graph showing the relationship between the focal length of the zoom lens according to the first embodiment and the zoom magnification for each of an optical zoom magnification, an electronic zoom magnification of the electronic camera, and an effective zoom magnification of the electronic camera. FIG. 5A illustrates aberrations of the zoom lens according to the first example at the time of focusing on infinity, where (a) is a wide-angle end state W, (b) is an intermediate focal length state M2, and (c) is a telephoto end state. Each aberration diagram at T is shown. FIG. 6 is a configuration diagram of a zoom lens lens according to a second embodiment of the present invention. 6 is a graph showing the relationship between the focal length and zoom magnification of a zoom lens according to the second embodiment for each of an optical zoom magnification, an electronic zoom magnification of an electronic camera, and an effective zoom magnification of the electronic camera. FIG. 6A shows various aberration diagrams of the zoom lens according to Example 2 when focusing on infinity, where (a) shows the wide-angle end state W, (b) shows the intermediate focal length state M2, and (c) shows the telephoto end state. Each aberration diagram at T is shown. FIG. 6 is a configuration diagram of a zoom lens lens according to Example 3 of the present invention. 10 is a graph showing the relationship between the focal length and zoom magnification of the zoom lens according to the third embodiment for each of the optical zoom magnification, the electronic zoom magnification of the electronic camera, and the effective zoom magnification of the electronic camera. FIG. 6A shows various aberration diagrams of the zoom lens according to Example 3 at the time of focusing on infinity, (a) shows the wide-angle end state W, (b) shows the intermediate focal length state M2, and (c) shows the telephoto end state. Each aberration diagram at T is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electronic camera 11 Shooting lens 12 Low pass filter 13 Image pick-up element 14 Zoom drive motor 15 Drive apparatus 16 Image generation part 17 Lens position detection apparatus 18 Electronic zoom magnification calculation part 19 Electronic zoom processing part 20 Effective focal distance calculation part 21 Display generation part 22 Display monitor 23 Record generation unit 24 Recording device

Claims (4)

In order from the subject side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, and the first lens group and the third lens group are A zoom lens that changes the focal length by moving to the subject side;
Detecting means for detecting a position of the third lens group from the first lens group;
Imaging means for converting a subject image formed by the zoom lens into an electrical signal;
Image generating means for generating an image from the signal of the imaging means;
Electronic zoom means for varying the electronic zoom magnification of an arbitrary part of the image formed by the image generation means,
The electronic zoom magnification is set to 1 in the wide-angle end state and the telephoto end state of the zoom lens,
The electronic zoom means changes the electronic zoom magnification according to a signal from the detection means,
When the movement amount of the first lens group from the wide-angle end state to the telephoto end state of the zoom lens is Δ1, and the focal length of the first lens group is f1,
0.1 <Δ1 / f1 <0.6
An electronic camera characterized by satisfying Effective focal length detection means for detecting an effective focal length based on the focal length of the zoom lens and the electronic zoom magnification;
The electronic camera according to claim 1 , further comprising an image recording unit capable of recording the focal length of the zoom lens and the effective focal length together with the image generated by the image generation unit. Effective focal length detection means for detecting an effective focal length based on the focal length of the zoom lens and the electronic zoom magnification;
The effective focal length, or the electronic camera according to claim 1 or 2, characterized in that it has a display means for displaying the effective zoom factor is calculated by the product of the optical zoom magnification and the electronic zoom magnification of the zoom lens. The electronic camera according to any one of claims 1 to 3, wherein the electronic zoom magnification in an intermediate focal length state of the zoom lens is equal to or less than 1.4 times.

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