Mobile, stereo, autofocus cameras present unique challenges for robust and efficient depth estimation. Specifically, existing approaches for calibration of the stereo camera intrinsic and extrinsic parameters are inadequate because of per-shot changes in the configuration, long-term mechanical drift, extremely constrained manufacturing processes, and the requirement for real-world robustness. We present a hybrid strategy that combines a single-photo of a calibration grid in an offline step with online blind refinement, which satisfies all of these goals.