| 摘要 |
PURPOSE:To obtain a highly efficient and compact lens system, by using a plastic lens having an aspherical surface, in a lens system which varies magnification by changing an interval between the first lens group having negative refractive power and the second lens group having positive refractive power. CONSTITUTION:The first lens group having negative refractive power consists of a negative meniscus lens whose convex surface has been faced to an object side, an aspherical lens which consists of plastic and has small refractive power, a negative meniscus lens whose convex surface has been faced to the object side, and a positive meniscus lens whose convex surface has been faced to the object side, the front-element diameter is made small by using a negative lens for the first lens, and the spherical aberration of the telephoto side by using a positive meniscus lens for the final lens of the first lens group. In order to correct distortion at the wide angle side, a plastic aspherical lens whose refractive power is small is used, and also various aberrations are corrected by limiting four numerical values. |
