The Hexagon program had a huge number of talented people working on it. Three of them were, in my opinion, the best engineers. They were:
1. Joe Vollaro, a mechanical engineer who understood the the basics of design engineering, kinematics and the intricacies of mounting optical elements, and paying attention to details better than anyone
2. Tony Bassaro, also a mechanical engineer who was a great designer of all kinds of moving and fixed mechanisms and the skills and tools to fabricate them.
3. Dick Carricato, an electrical engineer who was an expert in servomechanisms (control systems). He knew the whole complicated Hexagon system and how it worked better than anyone. He was the first to be called in the middle of the night to help diagnose problems in the lab or in orbit. Dick worked closely with two other fine electrical engineers, Marty Yellin and Dick Labinger. They designed the closed loop servo system that perfectly synchronized the speed and position of the fast moving film with the moving optical image at the focal plane. I salute all of them.