Patent ID: 7586690

Claim:
A projection type zoom lens comprising: a first lens group having a negative refractive power; and second to sixth lens groups having positive refractive powers, wherein: the first to sixth lens groups are arranged in order from a magnification side, the first lens group comprises at least one negative lens which has an anomalous dispersion property and which has 70 or more in Abbe number, at least one positive lens is included in the third to fifth lens group, the at least one positive lens which has an anomalous dispersion property and which has 70 or more in Abbe number, at least one of the negative lens having the anomalous dispersion property is cemented to a positive lens adjacent to the negative lens, at least one of the positive lens having the anomalous dispersion property is cemented to a negative lens adjacent to the positive lens, during variation of magnification, the second to fifth lens groups move and the first and sixth lens groups are fixed, during focus adjustment, the first lens group moves, and the following conditional expression (1) is satisfied: bf/fw≧ 2.7 (1) where bf denotes a back focus, and fw denotes a focal length of the entire system at a wide-angle end.