If you were wondering about those recently posted photos of Carl from 1968, I did some additional research and found more information about the photo session.
It was for the German magazine BRAVO, and the photographer — Wolfgang Heilemann — sought to symbolize what each of the guys contributes to The Beach Boys’ output, at least, as far as BRAVO was concerned in an article in 1969. Here is the translated gist of it:
Carl was responsible for the music (calling the tune, which, in German, is “die erste Geige spielen”… Geige being violin), for selecting the setlist and arrangements for concerts, and "the others know: he has the best ear for music"; Dennis was the wildest, who loves women and who's the ladies' favorite; Al was the balancing member; Bruce was responsible for the financial side; and Mike was the most determined and sharp-tongued.