| 摘要 |
PURPOSE: A zoom optical system is provided to thinly reduce physical thickness by including a right-angle prism which totally reflects the entered light of an object in a reflecting surface. CONSTITUTION: A first lens group has a positive refractive power and a right-angle prism(110) from an object side. A second lens group has a negative refractive power. A third lens group has the positive refractive power. An iris is located between the second lens group and the third lens group. A fourth lens group has the positive refractive power. An IR-cutting filter(600) is located the back part of the fourth lens group. |
