"It was in the fifteenth year of the emperor Tiberius’ reign, when Pontius Pilate was governor of Judaea, when Herod was prince in Galilee, his brother Philip in the Ituraean and Trachonitid region, and Lysanias in Abilina, in the high priesthood of Annas and Caiphas, that the word of God came upon John, the son of Zachary, in the desert. And he went all over the country round Jordan, announcing a baptism whereby men repented, to have their sins forgiven: as it is written in the book of the sayings of the prophet Isaias, There is a voice of one crying in the wilderness, Prepare the way of the Lord, straighten out his paths. Every valley is to be bridged, and every mountain and hill levelled, and the windings are to be cut straight, and the rough paths made into smooth roads, and all mankind is to see the saving power of God." -Knox Bible
Luke 3:1 There is some uncertainty about the system on which the Romans computed the years of a given reign; probably the fifteenth year of Tiberius would be 28 or 29 a.d. by our reckoning.
Luke 3:2 Caiphas was the actual high priest; Annas, who had been deposed from that office, continued to exercise much influence.
"In the fifteenth year of the reign of Tiberius Caesar, when Pontius Pilate was governor of Judea, and Herod was tetrarch of Galilee, and his brother Philip tetrarch of the region of Ituraea and Trachonitis, and Lysanias was tetrarch of Abilene, during the high priesthood of Annas and Caiaphas, the word of God came to John the son of Zechariah in the desert. John went throughout the whole region of the Jordan, proclaiming a baptism of repentance for the forgiveness of sins, as it is written in the book of the words of the prophet Isaiah: A voice of one crying out in the desert: 'Prepare the way of the Lord, make straight his paths. Every valley shall be filled and every mountain and hill shall be made low. The winding roads shall be made straight, and the rough ways made smooth, and all flesh shall see the salvation of God.'"-NAB