Various imaging apparatuses, methods and their implementation are characterized herein. As may be implemented with one or more embodiments, a phase mask and optics operate to provide characterization of object depth and related rotational mobility of a feature corresponding to the object. In various implementations, the optics include a microscope having an objective and a detection pathway that operate with the phase mask for passing the light from the objective. Circuitry, such as light detector, processor or combination thereof operates with the phase mask and microscope to characterize the depth and rotational mobility, based on detected light passed via the microscope and the phase mask.