| 摘要 |
An image forming optical system includes, a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, and the first lens unit either includes a negative lens and a positive lens, or includes a negative lens, a negative lens, and a positive lens, and the second lens unit includes a first lens component and a second lens component, and the second lens component includes a cemented lens, and the third lens unit includes either one lens or two lenses as a whole, and a lens having a curvature of a surface on an image side larger than a curvature of a surface on the object is disposed nearest to an object, and the fourth lens unit includes one positive lens component. |
| 主权项 |
1. An image forming optical system comprising in order from an object side:
a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; a third lens unit having a negative refractive power; and a fourth lens unit having a positive refractive power, wherein at the time of zooming, distances between adjacent lens units change, and at the time of zooming from a wide angle end to a telephoto end, the first lens unit, after moving toward an image side, moves toward the object side, and a second lens unit moves only toward the object side, and a lens component is one of a single lens and a cemented lens, and the first lens unit consists of a first negative lens, a second negative lens, and a positive lens in order from the object side, and the second lens unit comprises in order from the object side, a first lens component and a second lens component, and a total number of lens components included in the second lens unit is two, and the first lens component either consists of a positive single lens, or consists of a cemented lens in which, a positive lens and a negative lens are cemented in order of the positive lens and the negative lens, and the second lens component consists of a cemented lens, and the third lens unit consists of either one lens or two lenses as a whole, and comprises a lens having an absolute value of a curvature of a surface on the image side larger than an absolute value of a curvature of a surface on the object side, which is disposed nearest to the object side, and the fourth lens unit consists of one positive lens component. |
