JP6690425B2 - Variable magnification imaging optical system with anti-vibration function - Google Patents

Description

  The present invention relates to a variable power imaging optical system used in a still camera, a video camera, etc., and more particularly to a variable power imaging optical system having a narrow angle of view and a vibration reduction function.

  The image-stabilizing function used in digital still cameras, etc. is becoming increasingly equipped with anti-vibration functions, and even when taking photographs with super-telephoto lenses, failures due to camera shake are reduced, making super-telephoto lenses familiar. There is. An example of a variable-magnification image-forming optical system having a vibration-proof function such that the half angle of view at the telephoto end is about 3.2 degrees or less is described in the patent document.

JP, 2005-191008, A JP, 2014-145801, A JP, 2005-129788, A

  Super telephoto lenses inevitably have the problem that it is difficult to make them smaller and lighter.

  First, since the super telephoto lens has a long focal length, the optical system generally tends to have a long overall length. Therefore, the super telephoto lens is required to reduce the ratio of the total length of the optical system to the focal length, that is, the so-called telephoto ratio. For that purpose, it is advantageous to dispose an element having a strong negative refractive power behind the optical system. When an element having a strong negative refractive power is arranged, the back focus of the optical system tends to be short. On the other hand, for the super-telephoto lens, there is a demand to use an optical system capable of extending the focal length by adding it to the image side of the master optical system, that is, a so-called rear teleconverter. In order to improve the aberration of the rear teleconverter itself, it is advantageous to loosen the refractive power of the rear teleconverter, but as the refractive power is loosened, the position of the rear teleconverter moves to the object side and the master optical system is moved. You will be approaching. Therefore, in order to be able to mount a high-performance rear teleconverter, it is necessary to secure a sufficient back focus, and in particular, it is necessary to secure a back focus on the wide-angle side where the back focus is short. In order to secure the back focus, it is advantageous that the negative refracting power behind the optical system is weak, and it is difficult to reduce the total length of the optical system.

  Second, in the super-telephoto lens, if the same F value is maintained, the entrance pupil diameter increases, so that the radial direction tends to increase in size. When the diameter of the diaphragm or the vibration-proof group increases with the diameter of the entrance pupil, the actuator unit itself for driving these in the radial direction also increases in size, and the entire lens barrel also increases in size. Therefore, suppression of these diameters is important.

  As a third point, in the image stabilization group, the larger the amount of displacement in the direction orthogonal to the optical axis required to correct the shake, the larger the stroke that the actuator unit should have, and the overall unit becomes large. There is also a problem that power consumption increases because the amount of work required for blur correction increases. Therefore, it is desirable to reduce the amount of displacement of the image stabilizing unit with respect to the amount of displacement of the image.

  As a fourth point, in a super-telephoto zoom lens, the amount of movement of each group due to zooming tends to be large, but since the mechanism for movement is provided inside the lens barrel, it is necessary to reduce the total length of the lens barrel. The amount of group movement is limited. A large amount of movement can be achieved by adopting a structure in which two barrels are extended, but since the structure in which two barrels are stacked is difficult, it is difficult to control the diameter of the lens barrel, and it is also disadvantageous in suppressing eccentricity of the moving group. Becomes

  In the zoom lens described in Patent Document 1, the reduction of the total length of the optical system at the wide-angle end has been achieved to some extent, but the reduction of the total length of the optical system at the telephoto end is insufficient. It is difficult to reduce the overall length of the lens barrel because the amount of movement associated with zooming from the wide-angle end to the telephoto end is large. In addition, the suppression of paraxial ray height in the image stabilizing group at the telephoto end is insufficient, and dissatisfaction remains in reducing the weight of the image stabilizing group.

  The variable power optical system described in Patent Document 2 often achieves the suppression of the movement amount associated with the variable power of the first lens group from the wide-angle end to the telephoto end, but does not suppress the total length of the optical system at the wide-angle end. Sufficient and the total length of the lens barrel when stored in the product is large.

  In the zoom lens system described in Patent Document 3, the amount of movement associated with zooming of the first lens unit from the wide-angle end to the telephoto end is large compared to the zoom ratio, and it is difficult to further expand the zoom ratio. In addition, the distance from the final lens group to the image plane at the wide-angle end is too short compared to the focal length, which makes it difficult to use the rear teleconverter.

In order to solve the above-mentioned problems, a first invention is, in order from the object 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. , A fourth lens unit having a positive refracting power and a fifth lens unit having a negative refracting power, and at the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens unit and the second lens unit is The distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group changes, and the distance between the fourth lens group and the fifth lens group increases. So that at least the first lens group, the third lens group, the fourth lens group, and the fifth lens group move toward the object side from the image side, and the second lens group, The 2a lens group is composed of a negative refracting power 2a lens group and a negative refracting power 2b lens group. Anti-vibration is performed by displacing in the direction orthogonal to the axis, and the 2a lens group is composed of only two lens components, in order from the object side, a G2a1 lens component having a positive refractive power and a G2a2 lens component having a negative refractive power. The G2a1 lens component having a positive refracting power and the G2a2 lens component having a negative refracting power are arranged with an air gap, and the G2a1 lens component having a positive refracting power and the G2a2 having a negative refracting power are arranged. The variable-magnification imaging optical system having a vibration-proof function is characterized in that the lens component does not include an air space inside and satisfies the following conditional expression.
(1) 0.55 <| f5 · (1-β5w) / fw | <0.75
(2) 0.55 <| β5w−β5t | <0.77
(3) 2.30 <| 1 / f2rw-1 / f2rt | / (1 / fw-1 / ft) <2.80
However,
f5 is the focal length of the fifth lens group,
β5w is the imaging magnification at the wide-angle end of the fifth lens group,
β5t is the imaging magnification at the telephoto end of the fifth lens group,
fw is the focal length at the wide-angle end of the entire system,
ft is the focal length at the telephoto end of the entire system,
f2rw is the combined focal length at the wide-angle end of the second lens group and the combined system thereafter.
f2rt is a combined focal length at the telephoto end of the second lens group and the combination system thereafter.
Is.

  A second aspect of the present invention is provided with the image stabilizing function according to the first aspect, wherein the second lens group is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end. A variable-magnification imaging optical system is used.

  A third invention is characterized in that only the fourth lens group is moved along the optical axis in a direction from the image side to the object side when focusing from infinity to a short distance. Alternatively, the variable magnification imaging optical system having the image stabilizing function described in the second invention is used.

A fourth invention is a variable power imaging optical system having a vibration isolation function according to any one of the first invention to the third invention, characterized in that the following conditional expression is satisfied.
(4) 0.70 <| LT2a / f2a | <0.85
However,
LT2a is the distance from the most object side surface of the 2a lens group to the image side focal point of the 2a lens group,
f2a is the focal length of the 2a lens group,
Is.

A fifth aspect of the invention is a variable power imaging optical system having the image stabilizing function according to any one of the first to fourth aspects, characterized in that the following conditional expression is satisfied.
(5) -0.025 <dpp2a / | f2a | <-0.005
However, dpp2a is the distance from the object side principal point of the 2a lens group to the image side principal point.

  In a sixth aspect, the third lens group includes at least three positive lenses and two negative lenses, has a biconvex positive lens closest to the object side, and has the most image side from the object side. Variable magnification imaging optics with an image stabilizing function according to any one of the first to fifth inventions, characterized in that it has a cemented lens composed of one positive lens and one negative lens in order. system.

  The present invention has been made in view of such a situation, and suppresses the entire length and outer diameter of the lens barrel at a half angle of view at the telephoto end of about 3.2 degrees or less, thereby achieving a sufficient back focus at the wide angle end. It is an object of the present invention to provide a variable power imaging optical system which is secured and has excellent anti-vibration performance.

It is a lens block diagram which concerns on Example 1 of the variable power imaging optical system provided with the image stabilizing function of this invention. 3 is a longitudinal aberration diagram at the time of focusing at infinity at the wide-angle end of the variable magnification imaging optical system having the image stabilizing function of Example 1. FIG. FIG. 3 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system having the image stabilizing function of Example 1. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees when focusing on an object at infinity at the wide-angle end of the variable magnification imaging optical system having the image stabilization function of Example 1. FIG. FIG. 6 is a longitudinal aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 1. FIG. 4 is a lateral aberration diagram at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilizing function of the first embodiment. FIG. 6 is a lateral aberration diagram when performing image stabilization with the optical axis inclined by 0.4 ° at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilization function of the first example. 6 is a longitudinal aberration diagram at the telephoto end and at infinity of the variable magnification imaging optical system having the image stabilizing function of Example 1. FIG. 3 is a lateral aberration diagram at the telephoto end and at infinity in the variable magnification imaging optical system having the image stabilizing function of Example 1. FIG. FIG. 6 is a lateral aberration diagram when performing image stabilization with the optical axis tilted by 0.4 degrees at the telephoto end and infinity focusing of the variable power imaging optical system having the image stabilization function of Example 1. It is a lens block diagram which concerns on Example 2 of the variable power imaging optical system provided with the image stabilizing function of this invention. FIG. 9 is a longitudinal aberration diagram at the time of focusing at infinity at the wide angle end of the variable power imaging optical system having the image stabilizing function of Example 2. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the wide angle end of the variable power imaging optical system having the image stabilizing function of Example 2. FIG. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees when focused on an object at infinity at the wide-angle end of the variable magnification imaging optical system having the image stabilization function of Example 2. FIG. 9 is a longitudinal aberration diagram at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilizing function of the second embodiment. FIG. 10 is a lateral aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 2; FIG. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted by 0.4 ° at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilization function of the second example. FIG. 10 is a longitudinal aberration diagram at the telephoto end and at infinity of the variable magnification imaging optical system having the image stabilizing function of Example 2; FIG. 10 is a lateral aberration diagram at the telephoto end and at infinity of the variable magnification imaging optical system having the image stabilizing function of Example 2; FIG. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted by 0.4 ° at the telephoto end of the variable power imaging optical system having the image stabilization function of Example 2, at the time of focusing at infinity. It is a lens block diagram which concerns on Example 3 of the variable_magnification imaging optical system provided with the image stabilizing function of this invention. FIG. 9 is a longitudinal aberration diagram at the time of focusing at infinity at the wide angle end of the variable magnification imaging optical system having the image stabilizing function of Example 3; FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system having the image stabilizing function of Example 3; FIG. 16 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees when focused on an object at infinity at the wide-angle end of the variable power imaging optical system having the image stabilization function according to the third embodiment. FIG. 10 is a longitudinal aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 3; FIG. 9 is a lateral aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 3; FIG. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted by 0.4 ° at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilization function of the third example. FIG. 13 is a longitudinal aberration diagram at the telephoto end and at infinity in the variable magnification imaging optical system having the image stabilizing function of Example 3; FIG. 9 is a lateral aberration diagram at the telephoto end and at infinity in the variable power imaging optical system having the image stabilizing function of Example 3; FIG. 9 is a lateral aberration diagram when performing image stabilization with the optical axis tilted by 0.4 ° at the telephoto end and at infinity of the variable power imaging optical system having the image stabilization function of Example 3. It is a lens block diagram which concerns on Example 4 of the variable_magnification imaging optical system provided with the vibration isolating function of this invention. FIG. 16 is a longitudinal aberration diagram at the time of focusing at infinity at the wide angle end of the variable power imaging optical system having the image stabilizing function of Example 4; FIG. 9 is a lateral aberration diagram at the wide-angle end and when focused on an object at infinity, in the variable power imaging optical system having the image stabilizing function according to the fourth embodiment. FIG. 16 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees when focused on an object at infinity at the wide-angle end of the variable power imaging optical system having the image stabilization function of Example 4. FIG. 10 is a longitudinal aberration diagram at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilizing function of the fourth embodiment. FIG. 16 is a lateral aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 4; FIG. 16 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 ° during infinity focusing in the middle of the variable power imaging optical system having the image stabilization function of Example 4. FIG. 10 is a longitudinal aberration diagram at the telephoto end and at infinity in the variable power imaging optical system having the image stabilizing function of Example 4; FIG. 10 is a lateral aberration diagram at the telephoto end and at infinity in the variable power imaging optical system having the image stabilizing function of Example 4; FIG. 16 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees at the telephoto end and infinity focusing of the variable power imaging optical system having the image stabilization function of Example 4. It is a lens block diagram which concerns on Example 5 of the variable power imaging optical system provided with the image stabilizing function of this invention. FIG. 16 is a longitudinal aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system having the image stabilizing function of Example 5; FIG. 16 is a lateral aberration diagram at the wide-angle end and when focused on an object at infinity, in the variable power imaging optical system having the image stabilizing function according to the fifth embodiment. FIG. 16 is a lateral aberration diagram of the variable magnification imaging optical system having the image stabilizing function according to the fifth embodiment when the image is shaken with the optical axis inclined by 0.4 ° at the wide-angle end and at infinity. FIG. 16 is a longitudinal aberration diagram at the time of focusing on an intermediate point at infinity of the variable power imaging optical system having the image stabilizing function of Example 5; FIG. 16 is a lateral aberration diagram at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilizing function of the fifth embodiment. FIG. 16 is a lateral aberration diagram when performing image stabilization in a state where the optical axis is inclined by 0.4 ° at the time of focusing on the middle and infinity of the variable power imaging optical system having the image stabilization function of the fifth example. FIG. 16 is a longitudinal aberration diagram at the telephoto end and at infinity of the variable magnification imaging optical system having the image stabilizing function of Example 5; 16 is a lateral aberration diagram at the telephoto end and at infinity in the variable magnification imaging optical system having the image stabilizing function of Example 5. FIG. FIG. 16 is a lateral aberration diagram when performing image stabilization with the optical axis tilted at 0.4 degrees at the telephoto end and infinity focusing of the variable power imaging optical system having the image stabilization function of Example 5;

  The variable power imaging optical system having the image stabilizing function of the present invention comprises 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 in order from the object side. It is composed of a lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power.

  Upon zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens At least the first lens group, the third lens group, and the fourth lens group such that the distance between the fourth lens group and the fourth lens group changes and the distance between the fourth lens group and the fifth lens group decreases. , The fifth lens group moves from the image side to the object side.

  The second lens group includes a 2a lens group having a negative refracting power and a 2b lens group having a negative refracting power, and the 2b lens group is displaced in a direction orthogonal to the optical axis to perform image stabilization.

  The 2a lens group is composed of only a G2a1 lens component having a positive refractive power and a G2a2 lens component having a negative refractive power in order from the object side. The G2a1 lens component and the G2a2 lens component are separated from each other with an air gap, and no air gap is included inside each component. That is, the lens component in the present invention is a single lens or a cemented lens and does not include an air gap therein.

  In order to suppress the total length of the optical system at the telephoto end, the first lens group and the second lens group are arranged separately with the refractive power of the first lens group being positive and the refractive power of the second lens group being negative, and at the telephoto end. It is better to form a strong telescopic power arrangement. On the other hand, in order to reduce the amount of movement of the first lens unit that accompanies zooming, that is, to reduce the change in the total optical system length at the wide-angle end and the telephoto end, use a reverse telephoto type refractive power arrangement at the wide-angle end and It is advisable to have a telephoto type refractive power arrangement at the end.

  Therefore, at the wide-angle end, the first lens group having a positive refractive power and the second lens group having a negative refractive power are arranged close to each other so that the combined refractive power thereof becomes negative, and the first and second lens groups are combined. It is preferable to dispose a rear lens group having a positive refracting power as a whole at a position away from the system toward the image side. In the present invention, the rear lens group is the third lens group, the fourth lens group, and the fifth lens group. In order to shorten the total length of the optical system at the wide-angle end where the total length of the optical system is the shortest, it is preferable that the rear lens group has a telescopic refracting power arrangement. Specifically, the rear lens group is a rear lens group 1 having a positive refracting power. And the rear lens group 2 having a negative refractive power, and the rear lens group 1 and the rear lens group 2 may be spaced apart at the wide-angle end. In the present invention, the rear lens group 1 is a composite system of the third lens group and the fourth lens group, and the rear lens group 2 is the fifth lens group.

  On the other hand, at the telephoto end, the rear lens group 1 and the rear lens group 2 are brought closer to each other, and further the entire rear lens group is brought closer to the second lens group so that the refractive power of the composite system after the second lens group is made negative. Then, by constructing a telephoto-type refracting power arrangement with the first lens group, it is possible to shorten the total length of the optical system at the telephoto end. The above configuration is advantageous in reducing the movement amount of the first lens group while reducing the total length of the optical system at the wide-angle end.

  Further, the rear lens group 1 having a positive refracting power is divided into two parts with an air gap through which light rays pass almost afocal as a boundary, and the air gap is appropriately changed in accordance with the magnification change. Astigmatism of the entire optical system in the inside can be appropriately controlled.

  For the above reasons, the variable power imaging optical system of the present invention is composed of the above-mentioned five groups.

  The second lens group of negative refracting power, which is sandwiched between the third lens group of positive refracting power and the first lens group of positive refracting power, tends to have a large absolute value of refracting power. It is easy to increase the displacement of the image in the direction orthogonal to the optical axis due to the displacement in the direction orthogonal to the axis. In a telephoto variable-magnification imaging optical system in which the amount of image displacement due to camera shake is likely to be large, a configuration is well known in which all or part of the second lens group is displaced in the direction orthogonal to the optical axis to perform image stabilization. . By using a part of the second lens group located on the image side for image stabilization, the number of image stabilization groups can be reduced and the diameter of the light flux can be suppressed, so that it is easy to reduce the weight of the image stabilization group and the followability of the image stabilization group. Is advantageous in. Therefore, in the present invention, the second lens group is divided into the 2a lens group and the 2b lens group in order from the object side, and only the 2b lens group is used as the image stabilizing group. In order to further reduce the diameter of the image stabilizing unit, the 2a lens unit has a G2a1 lens component having a positive refractive power and a G2a2 lens component having a negative refractive power arranged in order from the object side. The arrangement was formed. The two lens components are separated by an air gap. By increasing the number of interfaces with the air without forming the 2a lens group as a single cemented lens, it is possible to reduce the refracting power around a single surface, suppress aberrations in the 2a lens group, and increase the degree of freedom in aberration correction. Therefore, it is advantageous in imaging performance. Of course, it is possible to increase the degree of freedom of aberration correction by further increasing the number of components, but it is not preferable that the total number of constituent elements increases.

Conditional expression 1 to be satisfied by the variable power imaging optical system of the present invention relates to the focal length of the fifth lens group and the imaging magnification at the wide angle end, and is desirable for securing a sufficient back focus and shortening the total length of the optical system at the wide angle end. It defines the range.
(1) 0.55 <| f5 · (1-β5w) / fw | <0.75
However,
f5 is the focal length of the fifth lens group,
β5w is the imaging magnification at the wide-angle end of the fifth lens group,
fw is the focal length at the wide-angle end of the entire system,
Is.

  If the upper limit of conditional expression 1 is exceeded, the back focus at the wide-angle end becomes long, and the clearance on the image side of the optical system is advantageous, but it is difficult to shorten the total length of the optical system at the wide-angle end.

  If the lower limit of conditional expression 1 is not reached, the back focus at the wide-angle end becomes too short, and it becomes difficult to add an additional optical system to the image side of the optical system.

  By setting the upper limit of conditional expression 1 to 0.73, further to 0.71, and the lower limit of conditional expression 1 to 0.57, and further to 0.59, the effect of the present invention can be achieved more reliably. .

Conditional expression 2 to be satisfied by the variable power imaging optical system of the present invention relates to the difference in imaging magnification between the wide-angle end and the telephoto end of the fifth lens group, and a desirable range for the positions of the fifth lens group at the wide-angle end and the telephoto end. Is defined.
(2) 0.55 <| β5w−β5t | <0.77
However,
β5w is the imaging magnification at the wide-angle end of the fifth lens group,
β5t is the imaging magnification at the telephoto end of the fifth lens group,
Is.

  When the upper limit of conditional expression 2 is exceeded and the difference in imaging magnification between the wide-angle end and the telephoto end of the fifth lens group becomes large, the position of the fifth lens group at the wide-angle end becomes too close to the image plane, and an additional optical system is added. Or the position of the fifth lens group at the telephoto end becomes too far from the image plane, making it difficult to shorten the total length of the optical system.

  If the difference between the imaging magnifications of the fifth lens group at the wide-angle end and the telephoto end becomes small below the lower limit of conditional expression 2, the imaging magnification of the fifth lens group at the wide-angle end becomes too large and the fifth lens at the wide-angle end becomes large. Aberration variation due to manufacturing error of each lens element on the object side of the group becomes large, or the image forming magnification of the fifth lens group at the telephoto end becomes too small, and the focal length of the compound system up to the fourth lens group becomes too long. Therefore, it is disadvantageous in shortening the total length of the optical system at the telephoto end.

  By setting the upper limit of conditional expression 2 to 0.75, further to 0.73, and the lower limit of conditional expression 2 to 0.58, and further to 0.61, the effect of the present invention can be achieved more reliably. .

Conditional expression 3 to be satisfied by the present invention relates to a change of the combined refractive power of the second lens group and the subsequent lens groups due to zooming, and shows a desirable range for shortening the total length of the optical system.
(3) 2.30 <| 1 / f2rw-1 / f2rt | / (1 / fw-1 / ft) <2.80
However,
fw is the focal length at the wide-angle end of the entire system,
ft is the focal length at the telephoto end of the entire system,
f2rw is the combined focal length at the wide-angle end of the second lens group and the combined system thereafter.
f2rt is a combined focal length at the telephoto end of the second lens group and the combination system thereafter.
Is.

  When the upper limit of conditional expression 3 is exceeded and the change in the combined refractive power after the second lens group becomes large, the change in the total length of the optical system due to zooming becomes too small, making it difficult to suppress the total length of the lens barrel at the wide-angle end. Or, it becomes difficult to improve the imaging performance at the telephoto end.

  If the lower limit of conditional expression 3 is not reached and the change in the combined refractive power after the second lens group becomes small, the change in the total length of the optical system due to zooming becomes too large, that is, the amount of movement of the first lens group becomes too large. The length of the cam for moving the first lens unit becomes long, which makes it difficult to reduce the total length of the lens barrel at the wide-angle end.

  By setting the upper limit of conditional expression 3 to 2.77, further to 2.75, and the lower limit of conditional expression 3 to 2.34, and further to 2.38, the effect of the present invention can be achieved more reliably. .

  In the present invention, it is more desirable to fix the second lens group to the image plane. It is necessary to connect wiring to the second lens group including the image stabilization group for controlling the image stabilization. The wiring can be simply configured by fixing the second lens group.

  In the present invention, it is desirable to move the fourth lens group from the image side to the object side along the optical axis when focusing from infinity to a short distance.

  In order to perform high-speed focusing at the telephoto end, it is desirable to move a group that is lightweight and has a large image plane movement amount per unit movement amount. From the viewpoint of weight, the group located behind the optical system is desirable. Since the second lens group includes the image stabilizing group, it is difficult to reduce the weight, and the third lens group has an exit light flux that is close to an afocal, and thus the image plane movement amount per unit movement amount is too small.

  For this reason, the fourth lens group or the fifth lens group is desirable. However, if the fifth lens group is moved, the image formation magnification of the fifth lens group decreases as the lens moves to a short distance. The imaging magnification also becomes low, the photographing distance for obtaining a desired imaging magnification becomes short, and the required amount of movement of the fifth lens group tends to become large.

  When the fourth lens group is moved during focusing, since the incident light flux to the fourth lens group is almost afocal, there is almost no change in the imaging magnification of the fourth lens group, and the imaging magnification of the fifth lens group Since it does not change, the photographing distance for obtaining a desired imaging magnification can be made longer than that in the case of focusing by the fifth lens group, and the movement amount of the fifth lens group can be reduced. Therefore, a high-speed focusing operation can be realized by using the fourth lens group for focusing.

Conditional expression 4 relates to the telephoto ratio of the 2a lens group, and shows a desirable range for shortening the overall length of the optical system and reducing the diameter of the image stabilizing group.
(4) 0.70 <| LT2a / f2a | <0.85
However,
LT2a is the distance from the most object side surface of the 2a lens group to the image side focal point of the 2a lens group,
f2a is the focal length of the 2a lens group,
Is.

  When the upper limit of conditional expression 4 is exceeded and the telephoto ratio of the 2a lens group becomes large, the overall length of the optical system is shortened and the ray diameter of the 2b lens group is not sufficiently suppressed, and the weight reduction of the image stabilizing group is also insufficient.

  If the telephoto ratio of the 2a lens group becomes smaller than the lower limit of conditional expression 4, the effects of shortening the total length of the optical system and suppressing the diameter of the light beam become higher, but the refractive power of the lens component having the positive refractive power closest to the object side is increased. Becomes too strong, the variation of astigmatism due to the tilt of the lens is likely to be large, and the deterioration of performance due to manufacturing error is large.

  By setting the upper limit of conditional expression 4 to 0.83, further to 0.81, and the lower limit of conditional expression 4 to 0.74, and further to 0.78, the effect of the present invention can be achieved more reliably. .

Conditional expression 5 relates to the distance between the two principal points of the 2a lens group, and shows a desirable range for shortening the overall length of the optical system and reducing the weight of the image stabilizing group.
(5) -0.025 <dpp2a / | f2a | <-0.005
However,
f2a is the focal length of the 2a lens group,
dpp2a is the distance from the object-side principal point of the 2a lens group to the image-side principal point,
Is.

  Since the object-side principal point of the 2a lens group is located on the image side with respect to the image-side principal point, the total length of the optical system can be shortened. Further, since the axial ray diameter can be reduced in a shorter section, the ray diameter of the 2b lens group can be suppressed while shortening the overall length of the optical system.

  If the upper limit of conditional expression 5 is exceeded, the object-side principal point will be located too close to the object side with respect to the image-side principal point, and shortening of the overall length of the optical system and suppression of the ray diameter will be insufficient.

  When the value goes below the lower limit of conditional expression 5, the effect of shortening the total length of the optical system and suppressing the diameter of the light beam is increased, but the refracting power of the lens component having the positive refracting power closest to the object side becomes too strong, so that the lens tilt causes a non-correction. Fluctuations in point aberrations are likely to be large, and performance deterioration due to manufacturing errors is large.

  The lower limit of conditional expression 5 is set to -0.021, further to -0.017, and the upper limit of conditional expression 5 is set to -0.0055 and further to -0.0060, thereby more reliably achieving the effect of the present invention. can do.

  In the present invention, the third lens group is composed of at least three positive lenses and two negative lenses, and has a biconvex positive lens closest to the object side and one lens closest to the image side in order from the object side. It is desirable to have a cemented lens composed of a positive lens and one negative lens.

  The light flux diverged by the action of the second lens group is incident on the third lens group, and the light flux close to the afocal is emitted toward the fourth lens group. In order to suppress the occurrence of spherical aberration in the third lens group as a whole, the positive lens is divided into a plurality of pieces to reduce the occurrence of negative spherical aberration per sheet, and the negative lens is introduced to generate positive spherical aberration. Then, the spherical aberration generated by the positive lens may be canceled. By forming a plurality of negative lenses, it is possible to suppress the occurrence of particularly high-order spherical aberration, so that the residual spherical aberration in the entire third lens group becomes small, and the eccentricity of the lens elements forming the third lens group is reduced. Generation of axial coma aberration due to However, if the number of sheets is unnecessarily increased, downsizing becomes difficult and the manufacturing cost also rises.

  In the present invention, the positive lens of the third lens group is made to be three to suppress the occurrence of negative spherical aberration, and the negative lens is made to be two to make positive spherical aberration while suppressing high-order spherical aberration. The spherical aberration of the lens group is properly corrected. Further, in order to convert a divergent light flux into a substantially parallel light flux, it is desirable to dispose a refracting surface having a positive refractive power as large as possible on the object side of the third lens group, and a large positive refractive power on the object side of the third lens group. It is most desirable to dispose a biconvex positive lens having a refracting power of. On the contrary, it is desirable to arrange the refracting surface having a strong negative refracting power on the image side. In the third lens group having a positive refracting power as a whole, axial coma aberration due to decentering is likely to be remarkable in a lens element having a strong negative refracting surface or adjacent thereto. Therefore, in the present invention, a strong negative refracting surface is arranged on the image side of the third lens group by arranging a cemented lens composed of one positive lens and one negative lens in order from the object side on the most image side. At the same time, the assembly accuracy before and after that was improved.

  Next, the lens configuration and specific numerical data of each embodiment relating to the variable power imaging optical system having the image stabilization function of the present invention will be described. In the following description, the lens configurations will be described in order from the object side to the image side.

  In [Surface data], the surface number is the lens surface or aperture stop number counted from the object side, r is the radius of curvature of each surface, d is the distance between the surfaces, and nd is for the d line (wavelength λ = 587.56 nm). Refractive index, νd indicates the Abbe number for the d-line. BF represents back focus.

  In the surface numbered (aperture stop), the radius of curvature ∞ (infinity) for the plane or the aperture stop is entered.

  In [Various data], values such as the focal length are shown.

  [Variable interval data] indicates the variable interval and BF (back focus) value in each shooting distance state.

  The [lens group data] shows the surface number of the most object side constituting each lens group and the combined focal length of the entire group.

  In all the values of the following specifications, the focal length f, the radius of curvature r, the lens surface distance d, and the other units of length are millimeters (mm) unless otherwise specified. The same optical performance can be obtained in the system even in the case of proportional enlargement and proportional reduction, so the present invention is not limited to this.

  In the aberration diagrams corresponding to the respective examples, d, g, and C represent d line, g line, and C line, respectively, and ΔS and ΔM represent sagittal image plane and meridional image plane, respectively.

  Further, in the lens configuration diagrams shown in FIGS. 1, 11, 21, 31, and 41, S is an aperture stop, I is an image plane, and a chain line passing through the center is an optical axis.

  First Embodiment FIG. 1 is a lens configuration diagram of a variable power imaging optical system having a vibration isolation function according to a first embodiment of the present invention.

  From the object side, in order from the object side, 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, a fourth lens group G4 having a positive refractive power, and a negative lens group. The fifth lens group G5 having a refractive power of is arranged.

  The first lens group G1 is composed of, in order from the object side, a cemented lens made up of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3, and an image upon zooming from the wide-angle end to the telephoto end. Move from side to object side.

  The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a having a negative refractive power and a 2b lens group G2b having a negative refractive power.

  The 2a lens group G2a includes, in order from the object side, a positive refractive power G2a1 lens component G2a1 composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens having negative refractive power composed of a biconvex lens L5 and a biconcave lens L6. G2a2 lens component G2a2 which does not move during zooming, focusing and image stabilization.

  The 2b lens group G2b is composed of, in order from the object side, a biconcave lens L7, a cemented lens composed of a biconcave lens L8 and a positive meniscus lens L9 having a convex surface facing the object side, and is displaced in a direction orthogonal to the optical axis during image stabilization. , It does not move during zooming and focusing.

  The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a negative meniscus lens L12 having a convex surface directed toward the image side, a positive meniscus lens L13 having a convex surface directed toward the object side, and a negative lens having a convex surface directed toward the object side. It is composed of a cemented lens including a meniscus lens L14, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end.

  An aperture stop S is provided on the image side of the third lens group G3.

  The fourth lens group G4 includes a positive meniscus lens L15 having a convex surface facing the image side, a cemented lens including a biconvex lens L16 and a biconcave lens L17, and a biconvex lens L18. From the image side to the object side, and moves from the image side to the object side when focusing from infinity to a short distance.

  The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens L19 having a convex surface directed toward the object side, a biconcave lens L20, and a biconvex lens L21, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end. Moving.

Next, the following are specifications of the variable power imaging optical system having the image stabilizing function according to the first embodiment.
Numerical Example 1
Unit: mm
[Surface data]
Surface number rd nd vd
1 316.5000 2.0000 1.83481 42.72
2 89.7500 8.2000 1.49700 81.61
3 -415.0000 0.1500
4 88.0000 7.5300 1.49700 81.61
5 -1000.0000 d5
6 111.8000 2.9700 1.69895 30.05
7 750.0000 13.4100
8 340.0000 2.3500 1.54814 45.82
9 -119.0000 0.9000 1.83481 42.72
10 78.9000 6.1500
11 -340.0000 1.0000 1.72916 54.67
12 92.7000 2.3500
13 -51.9000 1.0000 1.72916 54.67
14 51.9000 2.5500 1.85478 24.80
15 410.0000 d15
16 118.0000 3.6500 1.59349 67.00
17 -57.4000 0.1500
18 60.9000 2.8500 1.59349 67.00
19 -505.5000 0.8600
20 -81.0000 1.0000 2.00100 29.13
21 -640.0000 0.1500
22 28.2900 4.1500 1.69895 30.05
23 50.3000 1.0000 2.00100 29.13
24 28.5000 4.1000
25 (aperture) ∞ d25
26 -1000.0000 2.1500 1.71736 29.50
27 -73.0500 0.1500
28 65.0000 4.2500 1.65844 50.85
29 -44.3000 1.0000 1.95375 32.32
30 187.5000 0.2500
31 57.7000 2.8500 1.55032 75.50
32 -292.5000 d32
33 77.9500 1.0000 1.95375 32.32
34 27.5600 6.9000
35 -77.9500 1.0000 1.49700 81.61
36 29.9300 5.3500 1.73800 32.26
37 -292.5000 BF
Image plane ∞

[Various data]
Zoom ratio 3.76
Wide-angle mid-telephoto focal length 103.16 200.12 387.95
F number 5.15 5.92 6.50
Full angle of view 2ω 23.36 12.01 6.21
Image height Y 21.63 21.63 21.63
Total lens length 221.6588 259.3522 281.5591

[Variable interval data]
Wide-angle mid-telephoto
d5 4.0000 41.6937 63.9000
d15 27.7000 21.1822 3.5000
d25 30.2000 17.4597 23.5100
d32 13.7500 6.5712 1.9773
BF 52.6388 79.0754 95.3018

[Lens group data]
Focal length of front surface
G1 1 160.36
G2 6 -36.02
G3 16 64.44
G4 26 53.20
G5 33 -58.91
G2a 6 -201.96
G2b 11 -41.44

  FIG. 11 is a lens configuration diagram of a variable power imaging optical system having a vibration isolation function according to the second embodiment of the present invention.

  From the object side, in order from the object side, 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, a fourth lens group G4 having a positive refractive power, and a negative lens group. The fifth lens group G5 having a refractive power of is arranged.

  The first lens group G1 is composed of, in order from the object side, a cemented lens made up of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3, and an image upon zooming from the wide-angle end to the telephoto end. Move from side to object side.

  The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a having a negative refractive power and a 2b lens group G2b having a negative refractive power.

  The 2a lens group G2a includes, in order from the object side, a positive refractive power G2a1 lens component G2a1 composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens having negative refractive power composed of a biconvex lens L5 and a biconcave lens L6. G2a2 lens component G2a2 which does not move during zooming, focusing and image stabilization.

  The 2b lens group G2b is composed of, in order from the object side, a negative meniscus lens L7 having a convex surface facing the object side, a biconcave lens L8, and a positive meniscus lens L9 having a convex surface facing the object side. It is displaced in the direction orthogonal to the axis and does not move during zooming and focusing.

  The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a negative meniscus lens L12 having a convex surface directed toward the image side, a positive meniscus lens L13 having a convex surface directed toward the object side, and a negative lens having a convex surface directed toward the object side. It is composed of a cemented lens including a meniscus lens L14, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end.

  An aperture stop S is provided on the image side of the third lens group G3.

  The fourth lens group G4 includes a positive meniscus lens L15 having a convex surface facing the image side, a cemented lens including a biconvex lens L16 and a biconcave lens L17, and a biconvex lens L18. From the image side to the object side, and moves from the image side to the object side when focusing from infinity to a short distance.

  The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens L19 having a convex surface directed toward the object side, a biconcave lens L20, and a biconvex lens L21, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end. Moving.

Next, the data values of the variable power imaging optical system having the image stabilization function according to the second embodiment are shown below.
Numerical Example 2
Unit: mm
[Surface data]
Surface number rd nd vd
1 383.9445 2.0000 1.83481 42.72
2 97.9473 8.0282 1.49700 81.61
3 -349.0740 0.1500
4 91.2892 7.0902 1.49700 81.61
5 -2143.1412 d5
6 82.9030 3.5493 1.67270 32.17
7 608.7718 12.1544
8 300.4145 2.2747 1.51823 58.96
9 -161.1029 0.9000 1.83481 42.72
10 66.9701 6.0217
11 1141.3206 0.7000 1.77250 49.62
12 68.9592 2.4562
13 -47.4075 1.0000 1.72916 54.67
14 59.2395 2.6757 1.85478 24.80
15 2784.5642 d15
16 172.5506 3.3649 1.59349 67.00
17 -54.2522 0.1500
18 67.1337 3.2813 1.59349 67.00
19 -186.5874 0.6594
20 -72.7942 0.9000 2.00100 29.13
21 -616.9846 0.1500
22 29.6945 4.0183 1.72825 28.32
23 56.4342 0.9228 2.00100 29.13
24 30.8416 4.9219
25 (aperture) ∞ d25
26 -1095.0260 2.4539 1.72825 28.32
27 -70.1808 0.1500
28 62.0016 4.3480 1.65844 50.85
29 -42.9138 0.9000 1.95375 32.32
30 131.1259 0.1500
31 63.2480 2.8987 1.59282 68.62
32 -174.0716 d32
33 82.4231 0.9000 1.95375 32.32
34 28.7075 8.1459
35 -67.6151 1.0000 1.49700 81.61
36 32.6751 5.2217 1.73800 32.26
37 -194.8957 BF
Image plane ∞

[Various data]
Zoom ratio 3.77
Wide-angle mid-telephoto focal length 102.76 199.70 387.76
F number 5.15 5.95 6.50
Full angle of view 2ω 23.47 12.07 6.22
Image height Y 21.63 21.63 21.63
Total lens length 221.8401 261.8286 287.2495

[Variable interval data]
Wide-angle mid-telephoto
d5 4.0000 43.9884 69.4089
d15 27.9519 20.2920 3.5000
d25 30.0659 18.2396 22.4197
d32 13.8400 7.4533 2.0000
BF 52.4451 78.3181 96.3837

[Lens group data]
Focal length of front surface
G1 1 170.69
G2 6 -37.81
G3 16 66.72
G4 26 52.95
G5 33 -60.42
G2a 6 -241.21
G2b 11 -40.95

  FIG. 21 is a lens configuration diagram of a variable power imaging optical system having an image stabilizing function according to a third embodiment of the present invention.

  From the object side, in order from the object side, 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, a fourth lens group G4 having a positive refractive power, and a negative lens group. The fifth lens group G5 having a refractive power of is arranged.

  The first lens group G1 is composed of, in order from the object side, a cemented lens made up of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3, and an image upon zooming from the wide-angle end to the telephoto end. Move from side to object side.

  The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a having a negative refractive power and a 2b lens group G2b having a negative refractive power.

  The 2a lens group G2a includes, in order from the object side, a positive refractive power G2a1 lens component G2a1 composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens having negative refractive power composed of a biconvex lens L5 and a biconcave lens L6. G2a2 lens component G2a2 which does not move during zooming, focusing and image stabilization.

  The 2b lens group G2b is composed of, in order from the object side, a negative meniscus lens L7 having a convex surface facing the object side, a biconcave lens L8, and a positive meniscus lens L9 having a convex surface facing the object side. It is displaced in the direction orthogonal to the axis and does not move during zooming and focusing.

  The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a negative meniscus lens L12 having a convex surface directed toward the image side, a positive meniscus lens L13 having a convex surface directed toward the object side, and a negative lens having a convex surface directed toward the object side. It is composed of a cemented lens including a meniscus lens L14, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end.

  An aperture stop S is provided on the image side of the third lens group G3.

  The fourth lens group G4 includes a biconvex lens L15, a cemented lens including a biconvex lens L16 and a biconcave lens L17, and a biconvex lens L18, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end, When focusing from infinity to a short distance, it moves from the image side to the object side.

  The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens L19 having a convex surface directed toward the object side, a biconcave lens L20, and a biconvex lens L21, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end. Moving.

Next, the following are specifications of the variable power imaging optical system having the image stabilizing function according to the third embodiment.
Numerical Example 3
Unit: mm
[Surface data]
Surface number rd nd vd
1 281.0524 2.0000 1.83481 42.72
2 87.1359 8.1687 1.49700 81.61
3 -433.4744 0.1500
4 83.3325 7.4649 1.49700 81.61
5 -2606.8195 d5
6 97.3930 3.3116 1.67270 32.17
7 802.6686 12.9789
8 465.0674 2.3545 1.51823 58.96
9 -116.1751 0.9000 1.83481 42.72
10 75.3021 5.7411
11 313.6299 0.7000 1.77250 49.62
12 59.8735 2.5913
13 -45.4793 1.0000 1.72916 54.67
14 53.0072 2.5405 1.85478 24.80
15 2482.8269 d15
16 212.9547 3.2170 1.59349 67.00
17 -53.3544 0.1500
18 71.5013 3.1944 1.59349 67.00
19 -169.6485 0.6512
20 -69.7076 0.9000 2.00100 29.13
21 -318.9235 0.1500
22 30.1579 3.5810 1.72825 28.32
23 63.1501 0.9000 2.00100 29.13
24 32.0108 4.8418
25 (aperture) ∞ d25
26 1000.0000 4.2282 1.72825 28.32
27 -77.3938 0.1500
28 59.2888 4.4092 1.65844 50.85
29 -42.4562 0.9000 1.95375 32.32
30 105.2665 0.1500
31 66.4124 3.0046 1.59282 68.62
32 -122.2411 d32
33 59.5783 0.9000 1.95375 32.32
34 26.4861 9.1882
35 -62.4646 1.0000 1.49700 81.61
36 31.1153 5.1852 1.73800 32.26
37 -407.7210 BF
Image plane ∞

[Various data]
Zoom ratio 3.75
Wide-angle mid-telephoto focal length 103.32 199.78 387.76
F number 5.11 5.95 6.49
Full angle of view 2ω 23.28 12.07 6.22
Image height Y 21.63 21.63 21.63
Total lens length 221.5222 255.5096 277.4861

[Variable interval data]
Wide-angle mid-telephoto
d5 6.1300 40.1200 62.0930
d15 26.8955 20.1311 3.5000
d25 29.1185 17.1336 22.3764
d32 14.8704 7.8662 2.0000
BF 47.9064 73.6596 90.9144

[Lens group data]
Focal length of front surface
G1 1 155.93
G2 6 -35.20
G3 16 66.68
G4 26 52.89
G5 33 -56.93
G2a 6 -189.99
G2b 11 -40.36

  FIG. 31 is a lens configuration diagram of a variable power imaging optical system having an image stabilizing function according to a fourth embodiment of the present invention.

  From the object side, in order from the object side, 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, a fourth lens group G4 having a positive refractive power, and a negative lens group. The fifth lens group G5 having a refractive power of is arranged.

  The first lens group G1 is composed of, in order from the object side, a cemented lens made up of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3, and an image upon zooming from the wide-angle end to the telephoto end. Move from side to object side.

  The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a having a negative refractive power and a 2b lens group G2b having a negative refractive power.

  The 2a lens group G2a is composed of, in order from the object side, a positive refractive power G2a1 lens component G2a1 composed of a positive meniscus lens L4 having a convex surface facing the object side and a negative refractive power G2a2 lens component G2a2 composed of a biconcave lens L5. It does not move during zooming, focusing and image stabilization.

  The 2b lens group G2b is composed of, in order from the object side, a biconcave lens L6, a biconcave lens L7, and a cemented lens consisting of a positive meniscus lens L8 having a convex surface facing the object side, and is displaced in a direction orthogonal to the optical axis during image stabilization. , It does not move during zooming and focusing.

  The third lens group G3 includes a biconvex lens L9, a biconvex lens L10, a negative meniscus lens L11 having a convex surface directed toward the image side, a positive meniscus lens L12 having a convex surface directed toward the object side, and a negative meniscus lens having a convex surface directed toward the object side. It is composed of a cemented lens including a meniscus lens L13, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end.

  An aperture stop S is provided on the image side of the third lens group G3.

  The fourth lens group G4 is composed of a biconvex lens L14 having a convex surface directed toward the image side, a cemented lens including a biconvex lens L15 and a biconcave lens L16, and a biconvex lens L17. To the object side, and from the image side to the object side when focusing from infinity to a short distance.

  The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens L18 having a convex surface directed toward the object side, a biconcave lens L19 and a biconvex lens L20, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end. Moving.

Next, the following are specifications of the variable power imaging optical system having the image stabilizing function according to the fourth embodiment.
Numerical Example 4
Unit: mm
[Surface data]
Surface number rd nd vd
1 332.7233 2.0000 1.83481 42.72
2 91.8105 7.9233 1.49700 81.61
3 -360.9941 0.1500
4 86.5762 7.1524 1.49700 81.61
5 -1940.8944 d5
6 84.2636 3.6317 1.59270 35.45
7 763.6713 14.2586
8 -612.0116 0.9000 1.80420 46.50
9 70.9704 6.0785
10 -1113.7475 0.7000 1.77250 49.62
11 80.6093 2.2135
12 -51.5145 0.7000 1.72916 54.67
13 53.9510 2.4166 1.85478 24.80
14 486.9825 d14
15 158.7700 3.2049 1.61800 63.39
16 -57.7538 0.1500
17 69.0471 3.2035 1.59349 67.00
18 -210.1234 0.7629
19 -74.5961 0.9000 2.00100 29.13
20 -631.0356 0.1500
21 30.8414 3.5561 1.72825 28.32
22 53.6451 1.2185 2.00100 29.13
23 31.8798 4.8654
24 (aperture) ∞ d24
25 -15324.0430 2.4606 1.69895 30.05
26 -71.1566 0.1500
27 67.7252 4.1384 1.65844 50.85
28 -42.5498 0.9000 1.95375 32.32
29 198.7562 0.1500
30 61.3238 2.6997 1.49700 81.61
31 -155.8477 d31
32 98.3849 0.9000 1.95375 32.32
33 30.1756 9.4270
34 -60.7049 1.0000 1.49700 81.61
35 36.4281 4.8554 1.73800 32.26
36 -128.9825 BF
Image plane ∞

[Various data]
Zoom ratio 3.77
Wide-angle mid-telephoto focal length 102.79 199.90 387.66
F number 5.17 5.92 6.46
Full angle of view 2ω 23.48 12.06 6.23
Image height Y 21.63 21.63 21.63
Total lens length 221.5668 258.6607 281.4130

[Variable interval data]
Wide-angle mid-telephoto
d5 4.0000 41.0935 63.8453
d14 28.7043 20.9328 3.5000
d24 29.1219 17.7654 22.4268
d31 13.8505 7.4096 2.000
BF 53.0731 78.6424 96.8239

[Lens group data]
Focal length of front surface
G1 1 160.50
G2 6 -36.28
G3 15 66.61
G4 25 52.86
G5 32 -61.91
G2a 6 -199.48
G2b 10 -41.29

  FIG. 41 is a lens configuration diagram of a variable power imaging optical system having an image stabilizing function according to a fifth embodiment of the present invention.

  From the object side, in order from the object side, 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, a fourth lens group G4 having a positive refractive power, and a negative lens group. The fifth lens group G5 having a refractive power of is arranged.

  The first lens group G1 is composed of, in order from the object side, a cemented lens made up of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3, and an image upon zooming from the wide-angle end to the telephoto end. Move from side to object side.

  The second lens group G2 is composed of, in order from the object side, a 2a lens group G2a having a negative refractive power and a 2b lens group G2b having a negative refractive power.

  The 2a lens group G2a includes, in order from the object side, a positive refractive power G2a1 lens component G2a1 composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens having negative refractive power composed of a biconvex lens L5 and a biconcave lens L6. G2a2 lens component G2a2 which does not move during zooming, focusing and image stabilization.

  The 2b lens group G2b is composed of, in order from the object side, a biconcave lens L7, a cemented lens composed of a biconcave lens L8 and a positive meniscus lens L9 having a convex surface facing the object side, and is displaced in a direction orthogonal to the optical axis during image stabilization. , It does not move during zooming and focusing.

  The third lens group G3 includes a biconvex lens L10, a biconvex lens L11, a negative meniscus lens L12 having a convex surface directed toward the image side, a positive meniscus lens L13 having a convex surface directed toward the object side, and a negative lens having a convex surface directed toward the object side. It is composed of a cemented lens including a meniscus lens L14, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end.

  An aperture stop S is provided on the image side of the third lens group G3.

  The fourth lens group G4 includes a biconvex lens L15, a cemented lens including a biconvex lens L16 and a biconcave lens L17, and a biconvex lens L18, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end, When focusing from infinity to a short distance, it moves from the image side to the object side.

  The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens L19 having a convex surface directed toward the object side, a biconcave lens L20, and a biconvex lens L21, and moves from the image side to the object side during zooming from the wide-angle end to the telephoto end. Moving.

Next, the following are specifications of the variable power imaging optical system having the image stabilization function according to the fifth embodiment.
Numerical Example 5
Unit: mm
[Surface data]
Surface number rd nd vd
1 348.8696 2.0000 1.83481 42.72
2 92.4127 8.0501 1.49700 81.61
3 -363.1535 0.1500
4 87.2024 7.4763 1.49700 81.61
5 -1290.1463 d5
6 99.0766 3.1416 1.68893 31.16
7 565.8859 12.9994
8 373.0898 2.1938 1.54072 47.20
9 -127.0932 0.9000 1.83481 42.72
10 76.6214 6.1241
11 -446.4016 1.0000 1.72916 54.67
12 84.3369 2.4470
13 -50.9474 1.0000 1.72916 54.67
14 54.7070 2.5161 1.85478 24.80
15 591.2889 d15
16 102.9496 3.7629 1.59349 67.00
17 -57.5197 0.1500
18 65.4412 2.9153 1.59349 67.00
19 -285.9449 0.7713
20 -78.7811 1.0000 2.00100 29.13
21 -1484.9917 0.1500
22 29.6660 4.2870 1.72825 28.32
23 52.9885 1.0000 2.00100 29.13
24 29.5569 4.0123
25 (aperture) ∞ d25
26 1438.0555 2.2214 1.71736 29.50
27 -77.7034 0.1500
28 61.8950 4.2185 1.65844 50.85
29 -46.4211 1.0000 1.95375 32.32
30 137.8382 0.4763
31 61.3208 2.7575 1.55032 75.50
32 -272.1997 d32
33 82.2525 1.0000 1.95375 32.32
34 28.5927 6.9048
35 -82.3743 1.0000 1.49700 81.61
36 30.7335 5.2740 1.73800 32.26
37 -280.9224
Image plane ∞

[Various data]
Zoom ratio 3.79
Wide-angle mid-telephoto focal length 102.25 199.58 387.56
F number 5.16 5.94 6.50
Full angle of view 2ω 23.62 12.07 6.21
Image height Y 21.63 21.63 21.63
Total lens length 221.6679 259.1126 281.5128

[Variable interval data]
Wide-angle mid-telephoto
d5 4.0000 41.4500 63.8456
d15 29.4448 22.0257 3.5000
d25 28.8749 15.8906 24.4349
d32 13.7096 6.4658 2.000
BF 52.5889 80.2353 94.6826

[Lens group data]
Focal length of front surface
G1 1 160.78
G2 6 -36.40
G3 16 64.91
G4 26 55.40
G5 33 -61.96
G2a 6 -207.60
G2b 11 -41.44

[Value corresponding to conditional expression]
Example 1 Example 2 Example 3
Conditional expression 1 ｜ f5 ・ (1-β5w) / fw ｜ 0.64 0.66 0.60
Conditional expression 2 ｜ β5w-β5t ｜ 0.72 0.73 0.76
Conditional expression 3 ｜ 1 / f2rw-1 / f2rt ｜ / (1 / fw-1 / ft) 2.55 2.41 2.68
Conditional expression 4 ｜ LT2a / f2a ｜ 0.81 0.80 0.79
Conditional expression 5 dpp2a / ｜ f2a ｜ -0.007 -0.014 -0.010

Example 4 Example 5
Conditional expression 1 ｜ f5 ・ (1-β5w) / fw ｜ 0.69 0.65
Conditional expression 2 ｜ β5w-β5t ｜ 0.71 0.68
Conditional expression 3 ｜ 1 / f2rw-1 / f2rt ｜ / (1 / fw-1 / ft) 2.51 2.54
Conditional expression 4 ｜ LT2a / f2a ｜ 0.80 0.81
Conditional expression 5 dpp2a / ｜ f2a ｜ -0.015 -0.008

  In the variable power imaging optical system having the image stabilizing function of the present invention, it is desirable that the following configuration is further included.

  It is desirable that the fourth lens group includes one negative lens, and that at least one positive lens is provided before and after this negative lens. By providing the negative lens in the fourth lens group, spherical aberration, axial chromatic aberration, etc. can be corrected in the fourth lens group, and fluctuations of these various aberrations due to focusing on a short distance can be suppressed. You can

  When a positive lens is arranged on one side with respect to a negative lens, for example, when a positive lens is arranged on the object side of the negative lens, the axial marginal ray height is lowered by the converging action of the positive lens and then enters the negative lens. There is a difference in the light passing height between the negative lens and the positive lens. Therefore, when decentering occurs between the positive lens and the negative lens due to a manufacturing error, an error that is asymmetric with respect to the optical axis occurs in the correction of spherical aberration, and decentering coma easily occurs.

  On the other hand, by arranging the positive lens divided into two pieces, it is possible to reduce the refractive power per positive lens, and also to suppress the spherical aberration occurrence itself, thereby suppressing the refractive power of the negative lens necessary for correction. You can By arranging the two positive lenses before and after the negative lens, it is possible to suppress the change of the axial marginal ray height in the fourth lens group, so that the asymmetry with respect to the optical axis of the correction of the spherical aberration at the time of decentering also occurs. It becomes difficult.

  The fourth lens group is located closer to the image plane at the wide-angle end, and in particular, the upper marginal ray at the peripheral field angle is incident on the upper side of the fourth lens group and is greatly refracted. Therefore, it is more desirable that the positive lens on the object side is further divided into two, and a positive lens, a positive lens, a negative lens, and a positive lens are sequentially arranged from the object side. It is more preferable to use either the negative lens in the fourth lens group or the adjacent positive lens as a cemented lens because decentering in the fourth lens group can be suppressed.

G1 First lens group G2 Second lens group G2a 2a Lens group G2b 2b Lens group G2a1 G2a1 Lens component G2a2 G2a2 Lens component G3 Third lens group G4 Fourth lens group G5 Fifth lens group S Aperture stop I Image plane

Claims (6)

In order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the fourth lens group having a positive refractive power, and the negative lens group It is composed of a fifth lens group having a refractive power of
Upon zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group And the distance between the fourth lens group changes, and the distance between the fourth lens group and the fifth lens group decreases, at least the first lens group, the third lens group, the fourth lens group, The fifth lens group moves in a direction from the image side to the object side,
The second lens group includes a 2a lens group having a negative refracting power and a 2b lens group having a negative refracting power, and is configured to displace the 2b lens group in a direction orthogonal to the optical axis to perform image stabilization.
The 2a lens group is composed of only two lens components, in order from the object side, a G2a1 lens component having a positive refractive power and a G2a2 lens component having a negative refractive power,
The G2a1 lens component having a positive refractive power and the G2a2 lens component having a negative refractive power are arranged with an air gap therebetween,
The G2a1 lens component having a positive refractive power and the G2a2 lens component having a negative refractive power do not include an air space inside,
A variable-magnification imaging optical system having a vibration-proof function, which satisfies the following conditional expression.
(1) 0.55 <| f5 · (1-β5w) / fw | <0.75
(2) 0.55 <| β5w−β5t | <0.77
(3) 2.30 <| 1 / f2rw-1 / f2rt | / (1 / fw-1 / ft) <2.80
However,
f5 is the focal length of the fifth lens group,
β5w is the imaging magnification at the wide-angle end of the fifth lens group,
β5t is the imaging magnification at the telephoto end of the fifth lens group,
fw is the focal length at the wide-angle end of the entire system,
ft is the focal length at the telephoto end of the entire system,
f2rw is the combined focal length at the wide-angle end of the second lens group and the combined system thereafter.
f2rt is a combined focal length at the telephoto end of the second lens group and the combination system thereafter.
Is.   2. The variable power imaging optical system with a vibration isolation function according to claim 1, wherein the second lens group is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end. .   The image stabilization system according to claim 1, wherein only the fourth lens group is moved along the optical axis in a direction from the image side to the object side when focusing from infinity to a short distance. Variable-magnification imaging optical system with functions. 4. A variable power imaging optical system having an image stabilizing function according to claim 1, wherein the following conditional expression is satisfied.
(4) 0.70 <| LT2a / f2a | <0.85
However,
LT2a is the distance from the most object side surface of the 2a lens group to the image side focal point of the 2a lens group,
f2a is the focal length of the 2a lens group,
Is. 5. A variable power imaging optical system having an image stabilizing function according to claim 1, wherein the following conditional expression is satisfied.
(5) -0.025 <dpp2a / | f2a | <-0.005
However, dpp2a is the distance from the object side principal point of the 2a lens group to the image side principal point.   The third lens group includes at least three positive lenses and two negative lenses, has a biconvex positive lens closest to the object side, and one positive lens closest to the image side from the object side. 6. A variable-magnification imaging optical system having a vibration-proof function according to any one of claims 1 to 5, characterized in that it has a cemented lens composed of one negative lens.

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