To provide a zoom lens for bright projection for which an F number is 1.7 to 1.9 in simple lens constitution.
A negative first lens group is constituted of a negative first group-first meniscus lens whose convex is turned to a screen side and a negative first group-second meniscus lens whose convex is turned to the screen side. A positive second lens group is composed of a positive second group-first lens whose convex is turned to the screen side and a positive third lens group is composed of a positive third group-first lens whose convex is turned to the screen side. A negative fourth lens group is composed of a fourth group-first lens whose concave is turned to an object point side, a cemented lens composed by cementing a negative fourth group-second lens whose both surfaces are concave and a positive fourth-third lens whose both surfaces are convex and surface on the object point side is aspherical, and a positive fourth group-fourth lens whose convex is turned to the object point side in the order from the screen side. A positive fifth lens group is composed of a positive fifth group-first lens whose both surfaces are convex.
Hiroyuki Nagai
Junpei Okada
Satoshi Nazuka
Hideyuki Mori
Hirohito Katsunuma