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In reply to the discussion: JFK Conference: James DiEugenio made clear how Foreign Policy changed after November 22, 1963 [View all]Octafish
(55,745 posts)...He spoke after Dr. Larry Sabato. Dr. Thompson formally about "One Second in Dallas" when President Kennedy may have been struck by two bullets. This is from memory (I promise to report more fully when I have time to replay his presentation and add to my notes):
Dr. Thompson reported on an error from his earlier research that had made him believe the President was struck in the back of the head just a fraction of a second before a bullet struck him from the front. The mistake came from measurements made of slight changes in position between two frames of the Zapruder film.
The mistake resulted from properties in the film that were not taken into account -- specifically how film registers bright light sources and less intense sources. This property means moving objects don't register equally on the film, introducing errors that turned up when measuring distance between points appearing on different frames. These discrepancies were greater than what the film could accurately record.
He and an associate, Keith Fitzgerald, reported how taking these inaccuracies in measurement into account removed the problems in timing that had been noticed when the Zapruder film timeline was overlayed on the sounds recorded on the Dictabelt timeline.
The audio and video record now match up precisely with an analysis that shows the president was still hit by two bullets that they report were separated by about 1/2 second -- not the tiny fraction of a second from the mistaken photo analysis. My hair stood on end when Robert J. Groden spoke a little later and reported how new analyses of the Zapruder film had revealed the president may have been struck twice in that 1/2 second.