| 摘要 |
PURPOSE: To provide a zoom lens suitable for a video camera and having a bright F number, a high variable power and a low cost. CONSTITUTION: This zoom lens is, in order from the object side, composed of a first lens group 1 having a positive refractive power, a second lens group 2 having a negative refractive power and moving at the time of power variation, a third fixed lens group 3 having a positive refractive power and a fourth lens group 4 having a positive refractive power and compensating the movement of an image plane at the time of power variation, the fourth lens group 4 is, in order from the object side, composed of a lens having a positive refractive power, a lens having a negative refractive power and a lens having a positive refractive power, either of lenses having positive refractive powers and the lens having a negative refractive power are formed with plastic and the other lenses having positive refractive powers are formed of inorganic glass and the conditional relation: 60<ν4 G is satisfied, where,ν4 G is Abbe number of a lens made of inorganic glass in the fourth lens group.
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