| 摘要 |
The invention is concerned with a small-format yet high-performance zoom optical system with a fewer lenses count, and an electronic system that incorporates it. The zoom optical system comprises, in order from its object side, a first lens unit G 1 of negative refracting power, a second lens unit G 2 of positive refracting power and a third lens unit G 3 of negative refracting power, in which zooming is implemented by movement of at least the second lens unit G 2 and the third lens unit G 3, thereby varying a space between adjacent lens units. The negative first lens unit G 1 is composed of one negative lens, the positive second lens unit G 2 is composed of one positive lens, and the negative third lens unit G 3 is composed of one negative lens. The negative lens in the third lens unit G 3 is in a negative meniscus shape with a concave surface on its image plane side.
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