ZOOM LENS FOR PROJECTION

摘要

PROBLEM TO BE SOLVED: To realize a zoom lens for projection having excellent optical characteristic. SOLUTION: In this zoom lens, 1st to 5th groups G1 to G5 are arranged in order from an enlargement side, and the zoom lens is provided with a diaphragm S between the 3rd group G3 and the 4th group G4 and has the distribution of refractive power being negative, positive, positive, negative and positive. The focal distance of the 1st group: f1, the focal distance of the 2nd group: f2, the focal distance of the 3rd group: f3, the focal distance of an entire system at a wide-angle end: fw, the focal distance of the entire system at a telephoto end: fT, a synthetic focal distance from the 2nd group to the 5th group at the wide-angle end: fpw, a synthetic focal distance from the 2nd group to the 5th group at the telephoto end: fpT, the mean value of the Abbe number of the material of a concave lens constituting the 1st group:ν1 and the mean value of the Abbe number of the material of a convex lens constituting the 2nd group:ν2 satisfy conditions: (1) 0.6<|f1/fw|<1.2, (2) 0.720.