| 摘要 |
A telephoto zoom lens having four lens groups of which the 1st, counting from the front, has a positive refractive power, the 2nd has a negative refractive power, the 3rd has a positive refractive power and the 4th has a positive refractive power. The 1st, 2nd and 3rd lens groups form a varifocal section, and the 1st and 2nd lens groups axially move in opposite directions to each other when zooming. The amounts of movement of the 1st and 2nd lens groups relative to each other are thus controlled to achieve a shortening of the total length of the lens system.
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