PURPOSE: To offer a compact zoom lens having high performance by using effectively an aspherical lens.
CONSTITUTION: In a zoom lens having four lens groups first lens whose group has a positive refractive power, the second lens has a negative refractive power, the third lens group has a positive refractive power, and the fourth lens group in order from an object side; zooming is executed from a wide angle side to a telephoto side by moving the first lens group and the third lens group to the object side, and moving or fixing the second lens group and the fourth lens group. A compact zoom lens is attained by forming an aspherical surface to the lens having a positive refractive power in the third lens group, eliminating the aberrating variation caused by zooming, and also preventing the lens system from becoming long and large. Therefore, R2 of a full line is an aspherical surface, Rp shown by a dotted line is a reference spherical surface which contacts to the center part, and the shape for weakening the positive refractive power in the peripheral part, that is to say, an aspherical surface quantity Ψ with a code reversing to XA is shared.
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