| 摘要 |
An optical system including five lens units having, in order from the object side, positive, negative, positive, negative, positive refracting powers respectively. The distances between the lens units change during zooming. The first and third lens units are located closer to the object side at the telephoto end than at the wide angle end of the zoom range. The first lens unit includes a negative lens, a first positive lens, and a second positive lens. The second lens unit includes a plurality of negative lenses and at least one positive lens. The third lens unit includes a plurality of positive lenses and at least one negative lens. The fourth and fifth lens units each include two lenses or less. The refractive indices of the at least one negative lens in the first lens unit, the at least one positive lens in the second lens unit, and the at least one negative lens in the third lens unit are not lower than 1.9. The optical system satisfies a certain condition. |
