3D calibration using openCV sample project

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Hi ! Hi! I'm trying to get the camera matrix using the calibration project, my question is how far should my chessboard be, to get the correct answer, I've run it in two different distances , I got quit huge difference : in 1m :

 3.3471130890406162e+003 0. 3.1950000000000000e+002 0.
3.3471130890406162e+003 2.3950000000000000e+002 0. 0. 1.

in 3m :

     6.4963025894020222e+002 0. 3.1950000000000000e+002 0.
6.4963025894020222e+002 2.3950000000000000e+002 0. 0. 1.

thanks in advance !