| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact zoom lens easily applied to a device and also having high optical performance by fixing the entire length of the lens, and made optimum to be used in a digital video camera and a digital still camera and having a variable power ratio being about 3. SOLUTION: This zoom lens 1 is constituted of a 1st lens group GR1 having positive refractive power, always fixed positionally and consisting of a biconvex lens, a 2nd lens group GR2 having negative refractive power, capable of moving positionally and consisting of a concave meniscus lens whose convex surface faces the object side and a convex meniscus lens whose convex surface faces the object side, a 3rd lens group GR3 having positive refractive power, capable of moving positionally and consisting of at least one aspherical lens having positive refractive power and one lens having negative refractive power, and a 4th lens group GR4 having positive refractive power, capable of moving positionally and consisting of a biconvex lens in this order from the object side. Then, the power is varied by moving the 2nd and the 3rd lens groups at a fixed ratio while putting a diaphragm IR fixed positionally with respect to an imaging surface in between, and also the variation of an image point is corrected by moving the 4th lens group.
|
