| 摘要 |
The invention provides a compact, light-weight varifocal lens system that has a varifocal ratio of about 3, comprises fewer lenses than in the prior art, has a short total length and is well corrected in terms of various aberrations from the wide angle to telephoto ends. This lens system comprises a first positive lens unit G1, a second positive lens unit G2 and a third negative lens unit G3, wherein varifocal motion is achieved by moving each unit in such a way that, from the wide angle to telephoto ends, the air space between the first and second lens units increases, while the air space between the second and third lens units decreases.
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