Inspired by the techniqueproposed by Zhang in [13],we proposed a new camera calibrationtechnique,which only requires observing threeor more planar con-centricconics at afew (at least two) different orientations. All computations involved are linear matrix manipulations. Compared with the classical techniqueswhere an expensive calibrationpattern is commomly used,our techniqueis easy to implement and moreflexible. UsingConicsalso simplifies the problem of correspondence.Both computersimulationand real data are used to test theproposed technique.