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<blockquote data-quote="BackdoorArts" data-source="post: 109763" data-attributes="member: 9240">Just found this on 3D Focusing from the Nikon site...&quot;...the focus tracking system is a&nbsp; predictive system that uses special algorithms to forecast the position&nbsp; of the subject at the moment the image is captured. The prediction is&nbsp; based on a measurement of the subject's movement and speed.Simple predictive tracking is very effective for pictures of a&nbsp; subject moving at constant speed toward the camera, but to provide&nbsp; maximum focusing performance for a subject that abruptly changes&nbsp; direction at high speed, or a subject with low contrast, moving&nbsp; randomly, the AF system must accumulate subject location data using&nbsp; multiple focus areas. The AF modules built into selected Nikon D-SLRs&nbsp; have as many as 51 focus areas that can detect vertical, horizontal and&nbsp; diagonal movement of the subject.&quot;If the cat's moving at you and the camera predicted the speed of movement incorrectly then that would be responsible for the changes you're seeing.&nbsp; I suspect this would be most variable at the minimal dof you've got.I rarely if ever use 3D focus tracking, even in shooting birds in flight (though that's the one time I consider it depending on the flight path).&nbsp; If you're analyzing a potential focus issue that's not the mode I'd be using.</blockquote>

[QUOTE="BackdoorArts, post: 109763, member: 9240"] Just found this on 3D Focusing from the Nikon site... [I]"...the focus tracking system is a predictive system that uses special algorithms to forecast the position of the subject at the moment the image is captured. The prediction is based on a measurement of the subject's movement and speed. [/I][I] Simple predictive tracking is very effective for pictures of a subject moving at constant speed toward the camera, but to provide maximum focusing performance for a subject that abruptly changes direction at high speed, or a subject with low contrast, moving randomly, the AF system must accumulate subject location data using multiple focus areas. The AF modules built into selected Nikon D-SLRs have as many as 51 focus areas that can detect vertical, horizontal and diagonal movement of the subject."[/I] If the cat's moving at you and the camera predicted the speed of movement incorrectly then that would be responsible for the changes you're seeing. I suspect this would be most variable at the minimal dof you've got. I rarely if ever use 3D focus tracking, even in shooting birds in flight (though that's the one time I consider it depending on the flight path). If you're analyzing a potential focus issue that's not the mode I'd be using. [/QUOTE]

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