Zoom lens and projection type display apparatus using the same

摘要

A zoom lens comprises first to fifth lens groups successively from the enlargement side. The first lens group is fixed upon changing power and has a negative refracting power and a focusing function. The second and third lens groups having a positive refracting power and the fourth lens group having a negative refracting power are moved with a mutual relationship so as to continuously change power and correct the image surface movement caused by the continuous change in power. The fifth lens group has a positive refracting power and is fixed upon changing power. The first to fifth lens groups satisfy predetermined conditional expressions concerning their focal lengths.