Rear conversion lens

摘要

A conversion lens upon attachment on the image side of a master lens increases the focal length of the entire system. The conversion lens comprises three components of negative, positive and negative powers in this order from the front, has a negative power as a whole, and satisfies the following conditions: 2.0<f1/f3<4.0 0.8<¦f2/f3¦<1.2 n1-n2>0.15 where fi and ni are the focal length and the refractive index of the glass of the i-th component counting from the front respectively.