Abstract: Article orientation determining apparatus is exemplified in apparatus for determining if the tip ends of corn cobs are leading or trailing as they advance toward a kernel cutter head. The cobs pass between a column of sequentially pulsed radiation emitters and corresponding detectors which scan successive slices of the article and develop binary data indicative of the number of emitters that are unblocked during each scan. A computer uses the data to determine orientation and provides signals for controlling devices that act on misoriented articles. Means are provided for reversing the machine to clear a jam condition, for setting the number of reversals, for setting minimum acceptable cob length, for testing operation and for performing other functions. The scanner head is constructed to resist hostile environmental conditions.