Flying to Christchurch, Morton met members of the local chapter to shoot the snapshots in a clubhouse.
"Beforehand they laid the ground rules. At times I felt very intimidated by them, but I never felt unsafe," Morton said.
The patched vests signal the members' status. To earn them they must endure a gruelling initiation period that can span a year before they are officially welcomed.
The Black Power was founded in the 1970s to counter the Mongrel Mob, with whom they have a bitter and decades-long rivalry.
Tensions boiled over last month, when shots were fired at a Mongrel Mob member's funeral procesion in Whakatane.
But Morton believes Black Power are not as violent as they once were, and says there is more to the group than meets the eye.
"What I saw on the day felt a lot more like a brotherhood than anything else.
"At times I felt like I was just hanging out with family, uncles and brothers, but at the same time you also knew and could feel that there was a dark side to them."