| 摘要 |
The present invention relates to a telephoto zoom lens system which is less variable in terms of aberrations incidental to zooming and focusing, and is of high image quality and large aperture ratio as well, and which consists essentially of a first lens group G1 having a positive refracting power, a second lens group G2 having a negative refracting power, a third lens group G3 having a negative refracting power, a fourth lens group G4 having a positive refracting power and a fifth lens group G5 having a positive refracting power. For zooming from the wide-angle zone to the telephoto zone, the second and third lens groups G2 and G3 are moved in conformity to specific conditional inequalities while the first and fifth lens groups G1 and G5 remain fixed, and fourth lens group G4 is moved separately from the movable lens groups G2 and G3 while acting primarily as means for compensating for an image surface position. Conditions concerning the zoom ratio that the second and third lens groups G2 and G3 bear and the zooming function of the third lens group G3 as well as conditions that the separation between the second and third lens groups G2 and G3 should be larger at the wide-angle end than at the telephoto end are all satisfied.
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