JP2003329932A5 - - Google Patents

Claims (40)

The most object side lens group which is located on the most object side and is fixed on the optical axis at the time of zooming and focusing operation;
The most image side lens group which is located on the most image side and is fixed on the optical axis at least during focusing operation;
At least a first moving lens group and a second moving lens group that are located between the most object side lens group and the most image side lens group and move on the optical axis at the time of zooming,
The most object side lens group, in order from the object side, comprises a negative lens component, a surface mirror having a reflecting surface for bending the optical path, and a positive lens component,
The most image side lens group has at least one aspheric surface;
A zoom lens characterized by that. In order from the object side, a first lens group that is composed of a positive lens component and is fixed as the most object side lens group at the time of zooming;
A second lens group as a first moving lens group having negative refractive power and moving on the optical axis at the time of zooming;
A third lens group as a second moving lens group having a positive refractive power and moving on the optical axis at the time of zooming;
The most image side lens group disposed on the most image side,
The first lens group includes, in order from the object side, a negative lens component and a surface mirror having a reflecting surface for bending the optical path;
The zoom lens according to claim 1, wherein the reflecting surface has a variable shape.   3. The zoom lens according to claim 2, wherein the second lens unit reciprocally moves along a convex locus on the optical axis on the optical axis when zooming from the wide-angle end to the telephoto end when focusing on an object point at infinity. The described zoom lens.   The zoom lens according to claim 1, wherein a focusing operation is performed by changing a shape of the reflecting surface. The reflective surface is composed of a thin film coated with metal or dielectric,
The thin film is connected to a power source through a plurality of electrodes and a variable resistor,
An arithmetic device for controlling a variable resistance value of the variable resistor;
The zoom lens according to claim 1, wherein the shape of the reflecting surface is variably configured by controlling a distribution of electrostatic force applied to the thin film. A zoom lens according to any one of claims 1 to 5;
An electronic imaging device comprising: an electronic imaging device disposed on the image side. 7. The electronic imaging apparatus according to claim 6, wherein when the horizontal pixel pitch of the electronic imaging element is a and the open F value at the wide angle end of the zoom lens is F, the following conditional expression is satisfied. .
F ≧ a / (1 μm) The inner diameter of the aperture stop that determines the open F value is fixed, and is provided with a lens having a convex surface facing the stop immediately before or after the stop. The electronic imaging apparatus according to claim 7, wherein an intersection point with the perpendicular line is located within 0.5 mm from the inside of the lens or the vertex of the convex surface. The electronic imaging apparatus according to claim 8, wherein the intersection point is located inside or within the top of the lens. A transmittance variable means for adjusting the amount of light guided to the electronic image pickup device by changing the transmittance is provided, and the transmittance variable means is disposed in an optical path in a space different from the space in which the diaphragm is disposed. The electronic imaging device according to claim 7, wherein: The shutter of adjusting the light reception time of the light beam guided to the electronic imaging device is provided, and the shutter is disposed in an optical path in a space different from the space in which the diaphragm is disposed. The electronic imaging device in any one. The electronic imaging apparatus according to claim 6, wherein no low-pass filter is disposed in an optical path from the incident surface of the optical system to the imaging surface. 12. The medium boundary surfaces arranged between the zoom lens and the imaging surface are all substantially flat, and have no spatial frequency conversion effect unlike an optical low-pass filter. The electronic imaging device according to any one of the above. The third lens group is composed of three lenses, and the three lenses are composed of a cemented lens component in which a positive lens and a negative lens are cemented and two lens components of a single lens, or The zoom lens according to any one of claims 2 to 5, wherein the zoom lens is composed of one lens component including three cemented lenses and moves only to the object side when zooming from the wide-angle end to the telephoto end. Zoom lens. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.9 <−f11 / √ (fw · fT) <2.4
1.6 <f12 / √ (fw · fT) <3.6
Where f11 is the focal length of the negative lens component in the most object side lens group, f12 is the focal length of the positive lens component in the most object side lens group, fw is the focal length of the entire system at the wide angle end of the zoom lens, and fT is the zoom lens. Is the focal length of the entire system at the telephoto end. An electronic image pickup apparatus comprising the zoom lens according to claim 15 and an electronic image pickup element disposed on an image side thereof, wherein the following conditional expression is satisfied:
1.4 <d / L <3.0
Where d is an air-converted length measured along the optical axis from the image side apex of the negative lens component to the object side apex of the positive lens component in the most object side lens group, and L is a pair of effective imaging areas of the electronic image sensor. It is angular. 17. The electronic imaging apparatus according to claim 16, wherein the negative lens component of the most object side lens group is constituted by a negative single lens, and satisfies the following conditional expression.

Where ν1N is the Abbe number on the d-line basis of the medium of the negative single lens in the most object side lens group, f1 is the focal length of the most object side lens group, fw is the focal length of the entire system at the wide angle end of the zoom lens, fT is the focal length of the entire system at the telephoto end of the zoom lens. 3. The zoom lens according to claim 1, wherein the negative lens component in the most object side lens group is configured by a negative single lens, and the positive lens component is configured by a positive single lens. The first lens group has a positive refractive power, the third lens group moves only to the object side during zooming, the most image side lens group includes an aspherical surface, and is fixed during zooming. The zoom lens according to claim 3, wherein: The zoom lens according to claim 2, wherein the following conditional expression is satisfied.
0.3 <−βRw <0.8
0.8 <fRw / √ (fw · fT) <2.0
Where βRw is the combined magnification after the third lens group at the wide-angle end when focusing on an object point at infinity, fRw is the combined focal length after the third lens group at the wide-angle end when focusing on an object point at infinity, fw Is the focal length of the entire system at the wide-angle end of the zoom lens, and fT is the focal length of the entire system at the telephoto end of the zoom lens. The third lens group includes three lenses, and the three lenses include a single lens and a cemented lens component in which a positive lens and a negative lens are cemented in order from the object side. The zoom lens according to any one of claims 2 to 5 and 14, wherein: The third lens group includes three lenses, and the three lenses include a cemented lens component in which a positive lens and a negative lens are cemented in order from the object side, and a single lens. The zoom lens according to any one of claims 2 to 5 and 14, wherein: The third lens group includes three lenses, and the three lenses include a cemented lens component in which a positive lens, a negative lens, and a positive lens are cemented in order from the object side. The zoom lens according to any one of claims 2 to 5 and 14, wherein: The zoom lens according to claim 21, wherein the following conditional expression is satisfied.
0.4 <R _C3 / R _C1   <0.8
However, R _C3 Is the radius of curvature on the optical axis of the surface closest to the image side of the cemented lens component in the third lens group, R _C1 Is the radius of curvature on the optical axis of the most object side surface of the cemented lens component in the third lens group. The zoom lens according to claim 22, wherein the following conditional expression is satisfied.
1.0 <R _C3 / R _C1   <10
However, R _C3 Is the radius of curvature on the optical axis of the surface closest to the image side of the cemented lens component in the third lens group, R _C1 Is the radius of curvature on the optical axis of the most object side surface of the cemented lens component in the third lens group. An electronic image pickup apparatus comprising the zoom lens according to claim 21 or 24 and an electronic image pickup element arranged on an image side thereof, wherein the following conditional expression is satisfied:

However, L is the diagonal length (mm) of the image sensor to be used. It is assumed that the image sensor is used so that the wide angle end angle of view includes 55 degrees or more. R _C2 is the radius of curvature on the optical axis of the cemented surface of the cemented lens component in the third lens group, ν _CP is the Abbe number of the positive lens medium of the cemented lens component in the third lens group, and ν _CN is the third lens group. Is the Abbe number of the medium of the negative lens in the cemented lens component. An electronic image pickup apparatus comprising the zoom lens according to claim 22 or 25 and an electronic image pickup element arranged on an image side thereof, wherein the following conditional expression is satisfied:

However, L is the diagonal length (mm) of the image sensor to be used. It is assumed that the image sensor is used so that the wide angle end angle of view includes 55 degrees or more. R _C2 is the radius of curvature on the optical axis of the cemented surface of the cemented lens component in the third lens group, ν _CP is the Abbe number of the positive lens medium of the cemented lens component in the third lens group, and ν _CN is the third lens group. Is the Abbe number of the medium of the negative lens in the cemented lens component. The zoom lens according to claim 23, wherein the following conditional expression is satisfied.
−4.0 <(R _CF + R _CR ) / (R _CF -R _CR <0
However, R _CF Is the radius of curvature on the optical axis of the surface closest to the object side of the three-piece cemented lens component, R _CR Is the radius of curvature on the optical axis of the most image-side surface of the three-piece cemented lens component. The zoom lens according to claim 23 or 28, wherein the following conditional expression is satisfied.
0.6 <Dc / fw <1.8
Here, Dc is the distance on the optical axis from the most object side surface to the most image side surface of the three-piece cemented lens component, and fw is the focal length of the entire system at the wide angle end of the zoom lens. 30. The zoom lens according to claim 23, 28 or 29, wherein the following conditional expression is satisfied.
0.002 / mm ² <Σ | (1 / Rci) − (1 / Rca) | ² <0.05mm ²
However, Rci is the radius of curvature on the optical axis of the i-th cemented surface from the object side of the triplet cemented lens component, and Rca is Rca = m / | Σ (1 / Rci) | (i = 1... M) Here, m is 2 of the number of joint surfaces. The zoom lens according to any one of claims 23, 28 to 30, wherein the following conditional expression is satisfied.
5 × 10 ^-Five <Σ | (1 / νcj + 1) − (1 / νcj) | ² <4x10 ^-3
Where νcj is the Abbe number of the medium on the i-th d-line basis from the object side of the three-piece cemented lens component, j = 1... N−1, where n is three of the number of lenses to be joined. . 32. The zoom lens according to claim 23, wherein the zoom lens satisfies the following conditional expression.
0.005 <Σ | ncj + 1−ncj | ² <0.5
Here, ncj is the refractive index of the medium based on the i-th d-line reference from the object side of the three-piece cemented lens component, j = 1. . The zoom lens according to claim 1, wherein the negative lens component of the most object side lens group is an aspherical surface. The zoom lens according to claim 33, wherein the following conditional expression is satisfied.
-2.5 <(R _1PF + R _1PR ) / ( R _1PF -R _1PR ) <0.6
However, R _1PF Is the radius of curvature of the positive lens component of the most object side lens group on the optical axis of the object side surface, R _1PR Is the radius of curvature on the optical axis of the image side surface of the positive lens component of the most object side lens group. 3. The zoom lens according to claim 2, wherein the second lens group includes two lenses of a negative lens and a positive lens in order from the object side. 36. The zoom lens according to claim 35, wherein the second lens group is a cemented lens component including a negative lens and a positive lens in order from the object side. 37. The zoom lens according to claim 36, wherein the following conditional expression is satisfied.
-1.6 <(R _2F + R _2R ) / (R _2F -R _2R ) <0.3
However, R _2F Is the radius of curvature of the second lens group (junction lens component) on the optical axis of the surface closest to the object side, R _2R Is the radius of curvature on the optical axis of the surface closest to the image side of the second lens group (junction lens component). The zoom lens according to any one of claims 1 to 5, 14, 15, 18 to 25, and 28 to 37, wherein the zoom lens satisfies the following conditional expression.
1.8 <fT / fw
Here, fT is the focal length of the entire zoom lens system at the telephoto end, and fw is the focal length of the entire zoom lens system at the wide angle end. 28. The electronic imaging apparatus according to claim 6, wherein a full angle of view at the wide-angle end of the electronic imaging apparatus is 55 degrees or more. 40. The electronic imaging apparatus according to claim 39, wherein a full angle of view at the wide angle end in the electronic imaging apparatus is 80 degrees or less.