JP2003329930A5 - - Google Patents

Claims (37)

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,
The most image side lens group that is located on the most image side and is fixed on the optical axis at least during focusing operation;
At least a moving lens group that is located between the most object side lens group and the most image side lens group and moves 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 reflective optical element having a reflection 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 optical lens unit having a reflective optical element having a reflecting surface for bending the optical path, and being fixed at the time of zooming as the most object side lens unit;
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 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,
A zoom lens, wherein the second lens group reciprocates along a locus convex toward the image side when zooming from the wide-angle end to the telephoto end when focusing on an object point at infinity.   3. The zoom lens according to claim 2, wherein the second lens group is extended toward the object side during a focusing operation on a short-distance object point.   3. The zoom according to claim 2, wherein a lens group that moves on an optical axis during a focusing operation on a short-distance object point is disposed between the third lens group and the most image side lens group. lens.   The third lens group is 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, and moves only to the object side when zooming from the wide-angle end to the telephoto end. The zoom lens according to claim 2, wherein the zoom lens is a zoom lens.   An electronic imaging apparatus comprising: the zoom lens according to claim 1; and an electronic imaging device disposed on an image side thereof. The most object side lens group includes, in order from the object side, a negative lens component, a reflective optical element having a reflecting surface for bending an optical path, and a positive lens component, and satisfies the following conditional expression: The zoom lens according to any one of 1 to 5.
1.0 <−f11 / √ (fw · fT) <2.5
1.4 <f12 / √ (fw · fT) <3.2
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 This is the focal length of the entire system at the telephoto end of the zoom lens. An electronic imaging apparatus comprising: the zoom lens according to claim 7; and an electronic imaging device disposed on an image side thereof, wherein the following conditional expression is satisfied.
0.7 <d / L <2.0
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. The electronic imaging apparatus according to claim 8, wherein the reflective optical element is a prism and satisfies the following conditional expression.
1.55 <npri
Here, npri is the refractive index of the medium at the d-line of the reflective optical element. 8. The zoom lens according to claim 7, 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.
26 <ν1n
−0.15 <√ (fw · fT) / f1 <0.5
Here, ν1n is the Abbe number on the d-line basis of the medium of the negative single lens of the most object side lens group, and f1 is the focal length of the most object side lens group. 3. The zoom lens according to claim 1, wherein the most object side lens group includes a negative single lens, a reflective optical element, and a positive single lens in order from the object side. 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 2, 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) <1.8
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, and fw is a zoom The focal length of the entire system at the wide-angle end of the lens, and fT is the focal length of the entire system at the telephoto end of the zoom lens. The zoom lens according to claim 3, wherein the following conditional expression is satisfied.
0.16 <D12min / √ (fw · fT) <0.26
However, D12min is the minimum value in the range that can be taken between the first lens group and the second lens group at the time of 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 zoom. This is the focal length of the entire system at the telephoto end of the lens. The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
1.0 <| fF | / √ (fw · fT) <6.0
However, fF is the focal length of the lens group that is arranged between the third lens group and the most image side lens group and moves on the optical axis during the focusing operation on the short-distance object point, and fw is the zoom lens. The focal length of the entire system at the wide-angle end, and fT is the focal length of the entire system at the telephoto end of the zoom lens. The third lens group includes two positive lenses and one negative lens, and the negative lens is cemented with at least one of the positive lenses. The described zoom lens. The zoom lens according to claim 16, wherein the third lens group includes a positive single lens and a cemented lens component obtained by cementing a positive lens and a negative lens in order from the object side. The zoom lens according to claim 16, wherein the third lens group includes a cemented lens component in which a positive lens and a negative lens are cemented in order from the object side, and a positive single lens. The zoom lens according to claim 17, wherein the following conditional expression is satisfied.
0.4 <R _C3 / R _C1   <0.85
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 18, wherein the following conditional expression is satisfied.
0.8 <R _C3 / R _C1   <1.3
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 imaging apparatus comprising: the zoom lens according to claim 17 or 19; and an electronic imaging device disposed on an image side thereof, wherein the following conditional expression is satisfied.

However, L is the diagonal length (mm) of the imaging device to be used, R _C2 is the radius of curvature of the cemented lens component in the third lens group on the optical axis of the cemented surface, and ν _CP is the cemented lens component in the third lens group. The Abbe number of the medium of the positive lens, ν _CN is the Abbe number of the negative lens medium of the cemented lens component in the third lens group. 21. An electronic imaging apparatus comprising: the zoom lens according to claim 18; and an electronic imaging device disposed on an image side thereof, wherein the following conditional expression is satisfied.

However, L is the diagonal length (mm) of the imaging device to be used, R _C2 is the radius of curvature of the cemented lens component in the third lens group on the optical axis of the cemented surface, and ν _CP is the cemented lens component in the third lens group. The Abbe number of the medium of the positive lens, ν _CN is the Abbe number of the negative lens medium of the cemented lens component in the third lens group. The zoom lens according to claim 1, wherein the negative lens component of the most object side lens group has an aspherical surface. The zoom lens according to claim 23, wherein the following conditional expression is satisfied.
-2.0 <(R _1PF + R _1PR ) / (R _1PF -R _1PR <1.0
However, R _1PF Is the radius of curvature on the optical axis of the object side surface of the positive lens component in the most object side lens group, R _1PR Is the radius of curvature on the optical axis of the image side surface of the positive lens component in 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. 26. The zoom lens according to claim 25, wherein the second lens group is a cemented lens component in which two lenses of a negative lens and a positive lens are cemented in order from the object side. 27. The zoom lens according to claim 26, wherein the following conditional expression is satisfied.
-1.5 <(R _2F + R _2R ) / (R _2F -R _2R <0.8
However, R _2F Is the radius of curvature on the optical axis of the surface closest to the object side in the second lens group (junction lens component), R _2R Is the radius of curvature on the optical axis of the surface closest to the image side in the second lens group (junction lens component). The zoom lens according to any one of claims 1 to 5, 7, 10 to 20, and 23 to 27, wherein the zoom lens satisfies the following conditional expression.
1.8 <fT / fw
Here, fw is the focal length of the entire zoom lens system at the wide-angle end, and fT is the focal length of the entire zoom lens system at the telephoto end. The electronic imaging apparatus according to any one of claims 6, 8, 9, 21, and 22, wherein a full angle of view at a wide angle end in the electronic imaging apparatus is 55 degrees or more. 30. The electronic imaging device according to claim 29, wherein a full angle of view at the wide angle end in the electronic imaging device is 80 degrees or less. The following conditional expressions are satisfied, where a is a horizontal pixel pitch of the electronic image pickup element and F is an open F value at the wide-angle end of the zoom lens. 23. The electronic imaging apparatus according to 22.
F ≧ a / (1 μm) An inner diameter of the aperture stop that determines the open F value is fixed, and includes a lens having a convex surface facing the stop immediately before or after the stop, and an optical axis and the optical axis from the aperture stop. 32. The electronic imaging apparatus according to claim 31, wherein an intersection with a perpendicular line is positioned within 0.5 mm from the inside of the lens or the vertex of the convex surface. 33. The electronic imaging apparatus according to claim 32, wherein the intersection point is located within the lens or within the surface apex. It comprises a transmittance variable means for adjusting the amount of light guided to the electronic imaging device by changing the transmittance, and the transmittance variable means is arranged in an optical path in a space different from the space in which the diaphragm is arranged. The electronic imaging device according to any one of claims 31 to 33. 35. The apparatus according to claim 31, further comprising a shutter for adjusting a light receiving time of the light beam guided to the electronic image sensor, wherein the shutter is disposed in an optical path in a space different from a space in which the diaphragm is disposed. An electronic imaging device according to claim 1. The electronic imaging apparatus according to any one of claims 31 to 35, wherein no low-pass filter is disposed in an optical path from the incident surface of the optical system to the imaging surface. 36. The medium boundary surfaces arranged between the zoom lens and the imaging surface are all substantially flat and have no spatial frequency conversion effect as in an optical low-pass filter. The electronic imaging device in any one.