https://theasc.com/articles/making-of-tron-1982
it required a tremendous amount of current to provide thousands of footcandles of bounce light. At one point Logan was using 12,000 amps, and the City of Burbank called the studio to notify them that they would be shut down if they continued to draw so much current. Fortunately the studio was able to rearrange their load and work things out with the city so that Logan and his crew could resume shooting after about 45 minutes.
"The depth of field was so critical we were talking about half an inch, and that gets a little weird trying to play an intimate scene with a C-stand up your back. We would usually have a camera assistant with a telescopic sight with a cross-hair, and he would tell me through hand signals whether the actor was drifting ahead or behind the mark, and I would then, through hand signals, try to help the actor regain his mark, all the while giving his Academy Award winning performance.”
