Image Forming Lens System and Image Pickup Apparatus Using the Same

摘要

An image forming lens system includes an aperture stop, and an image-side lens unit group which is disposed on an image side of the aperture stop. The image-side lens unit group includes a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power. Any one of the first image-side lens unit, the second image side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing, and the following conditional expression (1) is satisfied:;0.06<|ffo/f|<0.4   (1)where,f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, andffo denotes a focal length of the focusing lens unit.

主权项

1. An image forming lens system comprising:
an aperture stop; and an image-side lens unit group which is disposed on an image side of the aperture stop, wherein the image-side lens unit group includes in order from the aperture stop to the image side along an optical axis, a first image-side lens unit having a negative refractive power, a second image-side lens unit having a positive refractive power, and a third image-side lens unit having a negative refractive power, and any one of the first image-side lens unit, the second image-side lens unit, and the third image-side lens unit is a focusing lens unit which moves along the optical axis at the time of focusing from an object at infinity to an object at a close distance, and the following conditional expression (1) is satisfied:
0.06<|ff0/f|<0.4   (1) where, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and ffo denotes a focal length of the focusing lens unit.