The person outside the frame may be the reason everybody inside it is smiling.

Photographs record the people who were looked at, not the person who made them look that way. Whoever held the camera, pulled faces, kept the day running, is missing from the picture their presence produced. Families often find later that one member appears in almost nothing. Absence from the record is not absence from the occasion.

Hand the camera over sometimes so the person always behind it gets into the album. When you look through old pictures, ask aloud who took this one. Naming them puts a little of them back into the frame they made possible.