In this paper we present a new calibration approach for focused plenoptic cameras. We derive a new mathematical projection model of afocused plenoptic camera which considers lateral as well as depth distortion. Therefore, we derive a new depth distortion model directlyfrom the theory of depth estimation in a focused plenoptic camera. In total the model consists of five intrinsic parameters, the parametersfor radial and tangential distortion in the image plane and two new depth distortion parameters. In the proposed calibration we performa complete bundle adjustment based on a 3D calibration target. The residual of our optimization approach is three dimensional, wherethe depth residual is defined by a scaled version of the inverse virtual depth difference and thus conforms well to the measured data.Our method is evaluated based on different camera setups and shows good accuracy. For a better characterization of our approach weevaluate the accuracy of virtual image points projected back to 3D space.