Port of Departure

My G. Grandfather was from Vang Valdres Norway, and according to the emigration list from that area registered in 1854. What would of been the port he may have left out of? His older brother registered and left in 1852. But I cannot find their names on any lists from those years. The last name was Gundersen (Anders 1854, and Nils 1852) on the emigrants list. Thank you. J. Beatty