| 摘要 |
PURPOSE:To decrease the number of lenses and to shorten the overall lens length, by disposing the 1st meniscus lens having positive refracting power, the 2nd lens having negative refracting power, the 3rd lens having positive refracting power, and the 4th meniscus lens having negative refracting power, and forming the lens face on the object side of the 3rd lens to an aspherical face. CONSTITUTION:A lens face R5 is made into such an aspherical face by which the positive refracting power is decreased on the periphery of the lens, thereby decreasing the refraction quantity of a lower ray L to L' and correcting satisfactorily comatic aberration. The transverse aberration corrected well of comatic aberration is thus obtd. and the resolving power is considerably improved. If the lens face on the object side of the 3rd lens group is used, the lens shape that makes finishing t an aspherical shape easy is obtd. |
