Patent ID: 6169636
Filing Date: 2001-01-02
Classification: G02B

Abstract:
A zoom projection lens for forming an image of an object, said lens consisting in order from its image end to its object end of: (A) a first lens unit having a negative power; (B) a second lens unit having a positive power, said second lens unit being separated from the first lens unit by a first axial space which is varied during zooming; (C) an aperture stop located between the first lens unit and the second lens unit; and (D) an optional field lens unit; wherein: (i) the second lens unit consists in order from its image end to its object end of: (a) a first lens subunit having a positive power; and (b) a second lens subunit having a positive power, said second lens subunit being separated from the first lens subunit by a second axial space; and (ii) during focusing, the first lens subunit is moved to vary the second axial space.