In documentary filmmaking, a cameraman holds the objective eye (the camera) of the filmmaker, providing the objective lense through which truth is seen. A cameraman can manipulate the camera so as to cast the image in a certain emotional angle, but even then, what the camera sees may show a truth that contradicts the fillmaker's and the photography director's intentions [for an example of this contradiction, see the documentary Mad Hot Ballroom (2005)]. Since the camera itself is objective, cameramen/women attempt to honor that objectivity and remain true to the goal of capturing the truth of the moment being filmed.
In "Blues Ain't No Mockin Bird," the cameraman doesn't appear to express any overt attitude toward the Cain family until Granddaddy Cain appears. This is true even though the cameraman encroaches on the family property and won't leave when told to do so by Granny, as is evident when Granddaddy later tells him, "You standing in the misses’ flower bed...." This tresspassing isn't an attitude toward the Cain's that the camerman is expressing but rather a pursuit of a position for the all-seeing camera lense.
This idea is supported by the cameraman's immediate, unprotesting compliance with Granddaddy's gestured request to give him the camera. The camerman simply hands it over. Granddaddy proceeds to disable the camera and the cameraman reacts by holding the unusable pieces. The attitude that the cameraman displays toward Granddaddy and, by symbolic representation, the whole Cain family is one of yielding respect mixed with a good deal of awe at Granddaddy's imposing persona.