Soldiers that carried a camera in Vietnam took pictures of each other and then passed the camera to get a picture of themselves. Udden also took snapshots of the land, the people of Vietnam, artillery, helicopters, planes and anything else that caught his eye through the lens.
He used a Kodak Instamatic Camera instead of a 35mm because he needed something tough that would survive getting banged around in an ammo can at the bottom of his pack. So, though the images are unique and the colors amazing, he apologizes that some are not focused to a pinpoint.
I hope you enjoy what you see. If you want to know the stories that fit between these captured moments, I would suggest you read his memoir.