| 摘要 |
A zoom lens includes a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, a fourth lens group having negative refracting power and a fifth lens group having negative refracting power in order from an object side, in which the lens groups move in magnification change from a wide angle end to a telephoto end such that a gap between the first lens group and the second lens group increases and a gap between the second lens group and the third lens group decreases, a negative lens group disposed closer to an image focusing side than a diaphragm among all lens groups is set as a focusing lens group, and the focusing lens group moves toward the image focusing side at focusing from infinity to a close object, the zoom lens satisfies a conditional expression, and the focus lens group is composed of a single lens block of a meniscus shape provided with a concave surface at an image focusing side; and satisfies a different conditional expression. |
| 主权项 |
1. A zoom lens including a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power and a fifth lens group having negative refractive power in order from an object side,
wherein the lens groups move in magnification change from a wide angle end to a telephoto end such that a gap between the first lens group and the second lens group increases and a gap between the second lens group and the third lens group decreases; a negative lens group disposed closer to an image focusing side than a diaphragm among all lens groups is set as a focusing lens group, and the focusing lens group moves toward the image focusing side in focusing from infinity to a close object; the zoom lens satisfies conditional expression (1); and the focus lens group is composed of a single lens block of a meniscus shape provided with a concave surface at an image focusing side; and satisfies conditional expression (2) below:
[Expression 1]1.25≦β5T≦3.10 (1)Where
β5T: Lateral magnification in telephoto end of fifth lens group
[Expression 2]3.10≦ra4/rb4≦5.40 (2)Where
ra4: Curvature radius of object side surface of focus lens group rb4: Curvature radius of image focusing side surface of focus lens group |
