According to the Dale Myers synchronization timeline there was 2.7 seconds between the end of that segment of the Hughes film and the beginning of the Zapruder assassination segment (Z133) film. Based on 18.3 frames per second, “Z124” would be about a half-second before Z133. Subtract a half-second from 2.7 seconds and we have about 2.2 seconds between the end of the Hughes film segment and “Z124”.
However I find it very interesting that both Hughes and Dorman stopped filming at very, very close the same time as the “Z124” frame would have been exposed.
Hughes’ stoppage was for only six frames (~1/3 of a second). This is very unusual and I think could be a reaction to an early missed shot. In the Max Holland video, he says that Dorman said she stopped filming after the first shot. Her camera did stop filming for about three seconds (49-frames).
We can see the VP security car starting the turn onto Elm in the last segment of Hughes film on Houston at least 3 seconds before Hughes stopped filming on Houston.
But if you look at the zfilm frame 133 the VP car has just started the turn and the VP security car is not yet at the intersection and shows no obvious sign of beginning the turn. If you add 3 seconds or 55 frames to 133 that would put the end of the Hughes film sequence at z188. And Hughes definitely said that he stopped filming the motorcade before any of the shots (Trask, p. 265) and resumed after they ended.
