| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high power zoom lens having high optical performance over the whole variable power range while shortening the whole lens length satisfying specific conditions at the time of changing power from the wide angle end to its telephone end with respect to a five-group zoom lens. SOLUTION: The lens system has five lens groups consisting of a 1st group L1 having positive refractive power, a 2nd group L2 having negative refractive power, a 3rd group L3 having positive refractive power, a 4th group L4 having negative refractive power, and 5th group L5 having positive refractive power. At the time of changing power from the wide angle end to the telephoto end, conditions D1W<D1T, D2W>D2T, D3W<D3T, D4W>D4T, 3.3<β2T/β2W<6.6, 0.18<f1/fT<0.33 are satisfied. The DiW and DiT are air intervals between the i-th and (i+1)th groups on the wide angle end and the telephoto end, theβ2W,β2T are horizontal power values on the wide angle end and telephoto end of the 2nd group L2, the f1 is the focal distance of the 1st group L1, and the fT expresses the focal distance of the telephoto end of the whole system.
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