The mirror also independently pivots under {TAIL ~ the bias} of a spring about the mirror pivot axis to an erected operative position wherein its upper and lower parallel edges are disposed perpendicular to the optical axis of {HEAD ~ the lens} 
The mirror also independently pivots under { TAIL ~ the bias } of a spring about the mirror pivot axis to an erected operative position wherein its upper and lower parallel edges are disposed perpendicular to the optical axis of { HEAD ~ the lens }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD