Abstract: A focal point position correction apparatus for a camera with a zoom lens system, has an adjustment amount calculation device for calculating an adjustment amount .delta.h of at least one lens unit Gh in the zoom lens system using a formula based on focal length information that defines a change amount corresponding to the focal length of the entire lens system and correction coefficients pre-stored for back focus adjustment, and a lens unit driver for moving the lens unit Gh by the adjustment amount .delta.h along the optical axis in the respective focal length states so as to correct any deviation, of the focal point position with respect to the film surface of a best image surface, caused by manufacturing errors, over the entire zooming range.

Abstract: A camera system having a power zoom lens and an automatic focusing device, comprising a zoom motor for zooming the power zoom lens, a focal length detecting device for detecting a focal length of the power zoom lens, an object distance detecting device for detecting a distance of an object which is in focus, and a calculation device for calculating an image magnification in accordance with the focal length and the object distance detected by the focal length detecting device and the object distance detecting device, respectively, and then calculating a target focal length at which the image magnification is kept constant, in accordance with the object distance detected by the object distance detecting device.

Abstract: A focusing lens position controlling apparatus for a variable focal length lens includes a variable focal length lens having a focusing lens group, a distance measuring device for measuring the object distance information to an object, a focal length detecting device for detecting the focal length information of the variable focal length lens, a first calculating device for calculating an operation coefficient from the output value from the focal length detecting device regarding the focal length information, and a second calculating device for calculating the amount of movement of the focusing lens group from the output value from the distance measuring device regarding the object distance information and the operation coefficient.