The Zapruder 8mm film was shot at an average speed of 18.3 frames per second. It has been calculated that the motorcade was moving at 11.2 mph. This means that the forward movement would be a little less than one foot per frame [approx 10.8 inches]. The Warren Commmission states that it takes 2.3 seconds for bullets to be chambered and fired from a carbine like Lee Harvey Oswald was accused of using. Comparing seconds to frames this would be equivalent to 42.7 frames between shots being fired. The first shot is believed to be at z-157, the second shot is at z-224, or 67 frames later, and the third shot to the head of the president at z-313 was 89 frames after the second shot was fired. Assuming there were only three shots there would have been more than enough time for one person to do all the shooting.
However, there is compelling evidence that would indicate that LHO could not have been the person that shot either President John Fitzgerald Kennedy or Governor John B. Connally (negative paraffin test on his face rules out use of a rifle/carbine). The House Select Committee on Assassinations (HSCA) ruled that there was indeed more than one shooter and that there was at least one shot fired from the "grassy knoll" area. Governor Connally's wife stated that there were two distinct shootings, her husband's and the president's, as opposed to the "single bullet theory" put forward by the Warren Commission. Weighing all evidence, not just using the Zapruder film, there was indeed a conspiracy to kill JFK. I believe it was the CIA and other high ranking officials in our own government.
Any wonder why former president George Bush did not want the JFK Act passed???