Focus Distances - problems

[billell]

Using a Nikkor VR 18-200 f3.5-5.6 G IF ED lens with a Nikon D7000, I am getting what appear to be anomalies with the recorded Focus Distances in the ExifTool (version 9.81).

For example: two photos were taken of the same subject, from the same spot, within seconds of each other, with the same zoom lens, the focus points practically the same (on the same plane).
The same exposure – f14 at 1/200sec.
The only difference, the first was taken at a focal length of 29mm and the second a narrower view at 55mm.

ExifTool shows  the Focus Distance as follows :
The 29mm shot – 7.9mm
The 55mm shot – 21.13mm

Surely the focus distances should be the same. I did not move, the subject (2 fishing cobles moored together) did not move.
What could be causing the discrepancy in the focus distances, ExifTool, the camera, or the lens?

Any other similar camera/lens users experiencing the same problems?

Thanks for any explanations.
Bill

[Phil Harvey]

Hi Bill,

The reported focus distances are notoriously inaccurate for all camera makes.  And the accuracy is even worse for wide angle lenses since the depth of field is larger.

- Phil

[billell]

Thanks

Bill