An electronic device may include a dielectric cover layer defining a finger sensing surface and at least one optical image sensor below the dielectric cover layer. The electronic device may also include at least one optical element associated with the at least one optical image sensor. Light sources may be below the dielectric layer and may be selectively operable in subsets of light sources. A controller may be configured to sequentially operate respective adjacent subsets of light sources while acquiring biometric image data from the at least one optical image sensor.