INNER FOCUS TYPE TELEPHOTOGRAPHIC ZOOM LENS OF LARGE APERTURE RATIO

摘要

PROBLEM TO BE SOLVED: To provide an inner focus type telephotographic zoom lens of large aperture ratio that enables speedy focusing by employing an inner focus system and prevents significant aberration even in close range focusing.;SOLUTION: A zoom lens includes at least five lens groups in order from an object side: a firs lens group LG1 of positive refractive power, a second lens group LG2 of negative refractive power, a third lens group LG3 of negative refractive power, a fourth lens group LG4 of positive refractive power, and a fifth lens group LG5 of positive refractive power. When zooming power varies from a wide angle end to a telephoto end, all the second, third, and fourth lens groups LG2, LG3, and LG4 move to the image side. When focusing takes place, the third lens group LG3 moves.;COPYRIGHT: (C)2013,JPO&INPIT