Lens apparatus and camera system

A lens apparatus comprising:

• an optical system including a front lens group having a positive refractive power and configured to move to an object side during focusing from infinity to a close-distance object, and a rear lens group arranged on an image side of the front lens group and configured to be immovable during the focusing;
• a motor configured to move the front lens group;
• a guide barrel configured to guide a movement of the front lens group;
• and
• a cam barrel configured to rotate with respect to the guide barrel by driving the motor, to move the front lens group,
• wherein the motor is arranged adjacent to the image side of the cam barrel, and
• wherein the following conditional expression is satisfied:
• 0.20<Δ/L<0.30
• where Δ represents a moving distance of the front lens group during focusing from a state where the optical system is focusing on an object at infinity to a state where the optical system has a lateral magnification of −0.5, and L represents an entire lens length of the optical system focusing on the infinity.

A camera system comprising:

• a lens apparatus including
• an optical system including a front lens group having a positive refractive power and configured to move to an object side during focusing from infinity to a close-distance object, and a rear lens group arranged on an image side of the front lens group and configured to be immovable during the focusing,
• a motor configured to move the front lens group, and
• a holding member including, on the object side, a flange portion extending in a direction orthogonal to an optical axis of the optical system and configured to hold at least part of the rear lens group;
• and
• a light-receiving element configured to receive an image formed by the optical system,
• wherein the motor includes a coil, a casing housing the coil, and a shaft portion extending from the casing in an optical-axis direction of the optical system, and arranged at a position at which an end surface on the image side of the casing is on the object side with respect to the flange portion in the optical-axis direction.

A camera system comprising:

• a lens apparatus including
• a front lens group having a positive refractive power and configured to move to an object side during focusing from infinity to a close-distance object, and a rear lens group arranged on an image side of the front lens group and configured to be immovable during the focusing;
• a motor configured to move the front lens group,
• a guide barrel configured to guide the movement of the front lens group, and
• a cam barrel configured to rotate to the guide barrel due to drive of the motor, to move the front lens group;
• and
• a light-receiving element configured to receive an image formed by the optical system,
• wherein the motor is arranged adjacently to the image side of the cam barrel, and
• wherein the following conditional expression is satisfied:
• 0.20<Δ/L<0.30
• where Δ represents a moving distance of the front lens group during focusing from a state where the optical system is focusing on an object at infinity to a state where the optical system has a lateral magnification of −0.5, and L represents an entire lens length of the optical system focusing on the infinity.