Patent ID: 7852569

Claim:
An internal focusing zoom lens comprising: a stationary barrel including a focus-guide cam groove; a zoom cam ring including a focus-shift cam groove, said zoom cam ring being rotated about an optical axis when a zooming operation is performed; a focus cam ring including a focus cam groove, said focus cam ring being rotated about said optical axis and moved in said optical axis direction to move a focusing lens group in said optical axis direction when a focusing operation is performed; and a focus correction ring for moving said focus cam ring in said optical axis direction by rotation of said zoom cam ring, wherein said focus correction ring includes a focus correction cam-follower engaged in said focus-shift cam groove, said focus cam groove and said focus-guide cam groove, and wherein a position of said focus correction cam-follower in said focus cam groove changes via said focus-shift cam groove and said focus-guide cam groove in accordance with said rotation of said zoom cam ring when said zooming operation is performed.