People are taking pictures.
Folks are using their cameras.
Folks or people using cameras to take pictures as cameras are meant to take pictures.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_take(e1) & n_picture(x2) & n_people(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_use(e1) & n_camera(x2) & of(x2,x1) & n_thing(x1) & n_folk(x1))