| 摘要 |
A projection optical system of the present invention has a first lens group G1 being positive, a second lens group G2 being negative, a third lens group G3 being positive, a fourth lens group G4 being negative, a fifth lens group G5 being positive, and a sixth lens group G6 being positive in the named order from the object side, in which the second lens group G2 comprises an intermediate lens group G2M between a negative front lens L2F and a negative rear lens L2R and in which the intermediate lens group G2M is arranged to comprise at least a first positive lens being positive, a second lens being negative, a third lens being negative, and a fourth lens being negative in the named order from the object side. The present invention involves findings of suitable focal length ranges for the first to the sixth lens groups G1 to G6 and an optimum range of an overall focal length of from the second negative lens to the fourth lens with respect to a focal length of the second lens group G2. <IMAGE> |
