Nina Rindt timing for Jochen, she was usually by the side of the track stopwatch in hand. I wonder what Colin is musing about in the background of the second photo... which part to remove to make the car yet lighter, I suspect. I like how their gestures are echoed, I take it this wasn't the most productive session - note Jochen is in civvies, so maybe a car failure involved.

At this point they were just on the cusp of full electronic timing, in which Heuer was one of the leaders. Manual stopwatches would be used for decades to come in club racing, of course, but it's interesting to see them still used in full on, FIA-sanctioned international motorsport.