Camera or Lens Autofocus

When you have an auto focus lens mounted on a camera with it's own autofocus, is it the lens autofocus that is used or is it the camera autofocus that is used, or both.

The focus is always done in camera. Some lenses have a motor within them which is used to move the elements of the lens to the correct position as decided by the camera body others rely on the motor in the camera but not all bodies have this motor.

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Cameras don't have autofocus. Only the lens. The lens autofocuses by moving lens elements within the lens. That's either accomplished by a motor in the lens itself, or using a motor in the camera body. Nikon makes electrical connections between the body and the lens. If it cannot (due to different, pre-autofocus designs) then the lens needs to be manually focused.

The sensor in the camera measures whether focus has been achieved either by contrast detection on the sensor or by phase detection it passes this information and the direction to move the elements to the lens motor if the lens has a motor if not it uses the camera body motor to move the lens elements. I suppose it depends on what you think autofocus means. I think it's a system with feedback which involves the lens and the camera body but the body is the brains.

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The autofocus module is in the camera. How the lens elements are moved depends on whether the motor is in the lens, and if not, by a motor in the body (if the body has one). The motor moves according to the instructions sent to it by the AF module.

If the lens contains and autofocus motor, you will notice that is has no receptacle to receive drive from the camera. It's internal motor will always be used. An older autofocus lens with no motor will have a screw head that receives drive from the camera.

Thank you all for your time and input.