We describe an approximate model for coherent general cameras, which projects efficiently with user chosen accuracy. The rays of the general camera are partitioned into simple cameras that approximate the camera locally. The simple cameras are modeled with k-ray cameras, a novel class of non-pinhole cameras. The rays of a k-ray camera interpolate between k construction rays. We analyze several variants of k-ray cameras. The resulting compound camera model is efficient because the number of simple cameras is orders of magnitude lower than the original number of rays camera, and because each simple camera offers closed-form projection.