Abstract: Disclosed is are a diagnostic test reader and related methods or systems. In one embodiment, a smartphone, including diagnostic software and a camera, may be docked onto the reader so that the camera of the phone is coupled to a diffuser for imaging test strips or other test cartridges provided to the reader. Preferably, the diagnostic software is configured to interpret an image of the strip and provide diagnostic feedback via the interface of the phone. Light for producing the image may be from the flash of the smartphone camera or a light source inside the reader. The more specific details of the disclosed reader are described in connection with the figures.