3 july 1852 two siblings left Nannestad: Christopher Christophersen 40 years old and Johanne Christophersdatter 29 1/2 years old. They came from the farm Sandsnes No 18 and 19 right page.
There are no records of emigration as early as 1852 from that side of Norway. Most Norwegian records of emigration from the ports do not start until the mid 1860s.
It appears most have been transcribed on norwayheritage.Two or three landing in New York have not and they could be searched for on microfilm. The Drafna 1852 list I have access to doesn't have the brother and sister you seek. Those landing in Quebec may or may not be preserved, Canadian law requiring filing of landings (passenger lists) wasn't in effect until the 1860s. And there is at least one voyage from Norway to Hull which was operated as a "feeder" for a an unkown, different, larger vessel across the ocean to North America.