Synchronizing the Zapruder Film and the Hughes Film
By Michael Russ

Anyone remotely familiar with the assassination of John F. Kennedy is familiar with the Zapruder film. The film was created at the time of the assassination by Abraham Zapruder who was standing on a pedestal south of Elm Street and west of the position the Presidential Limousine was in at the time of the assassination. Robert Hughes who was standing in the street at the intersection Of Main and Houston made a lesser-known film. The motorcade traveled west on Main street, and made a right hand turn onto Houston Street directly in front of Hughes and then continued down Houston around 200 feet until it made the left turn onto Elm and into Dealey Plaza. The Hughes film was most famous because as Hughes filmed the motorcade traveling down Houston, the sixth floor window of the Texas School Book Depository building is in view. This is the site of the alleged "snipers nest" where shots were alleged to have been fired from only seconds later. Unfortunately When the President's Limousine had completed the turn, Hughes stopped filming. When he started filming again the Texas School Book depository was no longer in view. He did however film a motorcycle police officer making the turn from Main to Houston. It was later determined that this Police officer was H.B. McLain.

This officer's location became an important piece of evidence when The House Select Committee on Assassinations reinvestigated the Assassination of John F. Kennedy. One of the Dallas police officers had left the microphone on his motorcycle stuck open during the time of the assassination. A recording of what was transmitted over that microphone had been made. It was suggested that the officer was H.B McLain, and that he had recorded the sound of gunfire in Dealey plaza.

The firm Bolt Beranek and Newman Inc. did an Analysis of recorded sounds relating to the assassination of President John F Kennedy, and they determined that the microphone had indeed been in Dealey Plaza. Their key finding stated "Therefore, the probability that they obtained their match because the two matched patterns were due to the same source (gunfire from the knoll) is about 95%."

This conclusion came under fire from multiple directions, for more information on that debate see A review of the acoustical evidence

A key piece of the evidence that Bolt Beranek and Newman Inc. relied on to support their conclusion was the Hughes film. For the acoustic evidence to be accurate Officer McLain had to be located at specific locations at specific times. Unfortunately there was no photographic evidence showing McLains's position during the critical moments of the shooting. He was visible in the Hughes film at a time that must have been very close to the time of the shooting though. If the exact time that McLain appears in the Hughes film could be determined and reasonable assumptions are made about the time it would take him to go from where he is seen in the Hughes film, to the location he needed to be in at the time of the assassination, the acoustic evidence could either be supported or refuted.

Bolt Beranek and Newman reported:

"Our correlation detector that located the origin of gunfire also located the position of the radio that transmitted the gunfire sounds. It is important to show that the motorcycle trajectory determined by the detections is compatible with independent evidence about a motorcycle trajectory. The necessary independent evidence to show this compatibility is partially obtained from the positions of the Presidential limousine and a motorcycle shown in the movie taken by Hughes (see footnote on p. 62). This movie shows the limousine just turning Onto Elm St. just before a motorcycle passes that has turned onto Houston St. from Main St. We estimate that the motorcycle was at point M (Fig. 12) at that sighting. We estimate that the limousine was at the position of microphone 2(9) (Fig. 12) at that sighting, 215 ft north on Houston St. "

The figure may be difficult to read but microphone 2(9) is the microphone that is in line with the West curb of Houston Street approximately midway across the intersection of Elm.

Bolt Beranek and Newman gave no specifics about how this location was determined, but they go on to determine by the speed of the Presidential limousine, as seen in the Zapruder film, that McLain was in Position M as seen in the Hughes film at either 6.5 or 7.2 seconds before what they determined to be the first shot at Zapruder frame 190. Researchers have come to the general consensus that the Zapruder film ran at approximately 18.3 seconds per frame, this means that McLain would be in position M at what could be called Zapruder frame 71 or 58 (It should be noted that there was a stop in the Zapruder film at frame 132, so frame 71 and 58 referred to here our not actually frame number 71 and 58 as seen on the film, but represent the theoretical frames that would have been created had the film been continuous from frame 190 backwards 6.5 or 7.2 seconds. All Zapruder frame numbers lower than 132 used throughout this page will use those same assumptions).

In order to review this evidence it should be noted that the following cars were in the motorcade:

1. Lead Car - Ford - White Sedan
2. Presidential limousine - Lincoln - Black Convertible
3. Presidential Secret Service car - Cadillac - Black Convertible
4. Vice Presidential limousine - Lincoln - steel gray convertible
5. Vice Presidential Secret Service car - Ford Mercury - Yellow sedan
6. Dignitary car number 1 - Ford Mercury - white 2-door convertible
7. National Press pool car - Chevrolet - blue-gray sedan
8. Camera car number 1 - 1964 Chevrolet Impala - yellow 2-door convertible
9. Camera car number 2 - 1964 Chevrolet Impala - silver 2-door convertible
10. Camera car number 3 - 1964 Chevrolet Impala - gray 2-door convertible

Greg Jaynes is a Dallas assassination researcher, who questioned Bolt Beranek and Newman's conclusions about what the Hughes film shows. On his web site at The Scene of the Crime, he points out that in the Hughes film the furthest car that can be seen on Houston is the Vice Presidential Secret Service car, and even that car can be seen starting to make it's turn onto Elm at that point. He claims that That car can be seen starting to make the turn onto Elm at approximately Zapruder frame 160, so McLain could not travel the 180 feet necessary to be in the position predicted by the acoustic analysis in 30 Zapruder frames or 1.6 seconds.

But when you look at Zapruder frame 133 above, an argument could be made that the Vice Presidential Secret Service car, which can just be seen through the crowd, is in a similar position as the one seen in the Hughes film. Unfortunately the stop in the Zapruder prevents us from seeing any further back in time to see what the earliest possible time that the Vice Presidential Secret Service car can be in a position consistent with the Hughes film. While Jaynes goes on to make other arguments about why McLain could not have been in the position as dictated by the acoustic evidence, those claims will not be addressed in this article.

In a November 17, 2001 presentation entitled HEAR NO EVIL, THE ACOUSTICAL EVIDENCE IN THE KENNEDY ASSASSINATION, Dr. Donald B. Thomas attempted to refute the arguments made by Jaynes. Thomas Writes:

"There have been assertions that films and photographs prove that McLain was not or could not have been in the acoustically predicted locations. One of the challenges which has appeared on the internet is the assertion that the Hughes film proves McLain to have been in the wrong place at the wrong time. The basis for this claim is the angle of the car at the head of the column of cars seen on Houston Street in H-20. This car, a yellow mercury hardtop, is the fifth car in the motorcade, and contains a secret service contingent attached to the vice president, who was in the fourth car of the motorcade. One can clearly see that this car has pulled out of line and is starting its turn on to Elm Street.

According to the critics, this action corresponds to frame 160 of the Zapruder film. This map (Fig. 7), is a plot of the position of the cars seen at the intersection of Elm and Houston at frame 160. If this interpretation is correct; that it corresponds exactly or even closely to H-20, then McLain cannot possibly be in the locations required by the acoustical evidence because Z-frame 160 synchronizes to less than one sec before the first shot (at Z-175). McLain would have to travel about 180 feet in less than one sec, requiring a velocity of 140 mph.

But this interpretation is probably not correct. An important factor in this analysis is the speed of the motorcade. One can measure the speed of the cars by counting the number of frames it takes for the vehicle to pass objects in the background. In this case, Car-5 can be seen passing a lady in red from Z-frames 144 to 180. That is, it required 36 frames, or 2 sec, to travel its own length which was about 16 ft. This calculates to a speed of only 5.5 mph. This means that a small error in the car's position can mean a big error in the estimated time lapse between events.

On this map (Fig. 8) We have plotted an alternative interpretation of the car positions seen in H-20. This interpretation suggests that Car-5 began its turn prior to the point where it came into view of Zapruder's lens, and then because of the sharpness of the turn, had to make a second steering adjustment while in the intersection that is seen in the Zapruder film. The question is, which of these two interpretations is more likely to be correct. We would argue that a connection between the Hughes film and the Zapruder film can be made more accurately by relying on the cars closer to Hughes, because their position is less equivocal than the one farthest away. Such a car is car No. 8.

This map (Fig. 9) plots the positions of Car-8 as seen in the Zapruder film and as it is seen in the Hughes film. We can plot its position in the Zapruder film exactly, because it comes into alignment with an oak tree between Zapruder and Houston Street at frame 220. Moreover, we can measure the velocity of this car in the same manner that we measured that of Car-5, by measuring its change in position relative to stationary objects. In this instance it required 21 Z-frames to travel its own length. Because Car-8 is a two-door Chevrolet Impala its chassis length was 15 ft (180 inches according to the 1964 Chilton's manual). Its speed thus calculates to 8.5 mph (=12.5 ft/sec). The difference in speed between Cars-8 and -5 is understandable because the turns through Dealey Plaza were causing an accordion effect, such that the cars would bunch and slow down through the intersections, but then on leaving the intersection, space would open and the cars could speed up on the straight-aways.

The distance between Car-8's measured position at Z-220 and its estimated position at H-20 is 88 feet. At a speed of 12.5 ft/sec, the car would need 7 sec to cover the distance. At 18.3 frames per sec, H-20 would be equivalent to Z-90, not Z-160. This would place McLain's position at the Main Street intersection about 4.6 sec prior to the first shot. But, if one factors in the accordion effect, Car-8 was probably averaging between 6-8 mph and thus McLain's position in H-20 is likely closer to six to seven sec prior to the first shot, in accord with Hughes memory that the shots occurred several seconds after he stopped."

As can be seen in the Zapruder frame Thomas is correct and the position of camera car number 1 (car 8 of the motorcade) can be tied to the Zapruder film. But there is very little explanation of how he arrived at the conclusion that car 8 is in a position in the Hughes film that is 88 feet from the position seen in the Zapruder film at frame 220. His proof would appear to be his figure 8, but he makes no attempt to verify the accuracy of that figure.

Below, Hughes's position has been added to Thomas's Figure 8 and the crosswalk lines on Houston that are visible in the Hughes frame are drawn in. Lines of site for the Hughes frame, and lines of site through major landmarks on Houston, like the corners of the buildings, have also been added. The Hughes frame is directly below that diagram with the landmarks lettered to correspond to the letters that have been added to the Thomas figure 8.

A cursory view of Thomas's figure shows multiple errors. For instance, it is clear in the Hughes film that camera car number 2 (the 9th car in the motorcade) has completely passed the crosswalk on Houston, and that the front end of car number 10 is in line with the northern most stripe of the crosswalk. The Thomas figure has car 9 still in the middle of the crosswalk and car 10 just starting to enter it.

The lines of site that we have placed on Thomas's diagram are subject to a margin of error based on the precise location of Hughes and the actual positions of the cars across Houston. The positions of the cars in Thomas's figure relative to the fixed landmarks are so far away that it is clear that this figure is not reliable.

The critical car in Thomas's analysis is camera car number 1 (car number 8). In the Hughes film, the Corner of the Dal-Tex building is labeled E, and it appears that the front center of car 8 is directly in the line of site of that building. If you look at the Thomas diagram, that corner is slightly to the left of the center of car 7. Thomas seems to be off by a minimum of an entire car length plus any distance between car 7 and car 8.

Thomas's method of using car 8 to synchronize the Zapruder and Hughes film does have merit in spite of his flaws in executing it. What is needed is an accurate representation of the position of car 8 in the Hughes frame. As stated before, verifying Hughes's position and the actual positions of the cars across Houston are needed to use the positions of fixed landmarks to fix the distance that any car is up Houston. Another method can be used to help eliminate the need to know the distance the cars are across Houston.

Paul Seaton has developed this applet that is based strictly on the position of known positions of objects up and down Houston Street. The applet shows that the rear end of car number 8 is approximately 112 feet from Hughes, which is about 56 feet from the position that it can be seen in at Zapruder frame 220. That distance can then be matched up with the buildings in the background to determine how far across Houston the cars would be. The result shows the car to be just east of the center of Houston, and just west of the east set of stripes on the road. This seems to match well with other films that show the parade traveling down Houston in that general location.

Since the two positions that are shown are in the middle of the stretch between Main street and Elm Street it is not likely that there is much of an accordion effect during this time. If we use Thomas's calculated speed of 12.5 feet per second to determine that it would take car 8 approximately 4.5 seconds to travel from where it is seen in the Hughes film to where it is seen at Zapruder frame 220. At 18.3 frames per second the equivalent Zapruder frame for the Hughes frame (referred to as Hughes D in this paper) is approximately Zapruder frame 138.

As a further check let's study the original claim by Bolt Beranek and Newman that "We estimate that the motorcycle was at point M (Fig. 12) at that sighting. We estimate that the limousine was at the position of microphone 2(9) (Fig. 12) at that sighting, 215 ft north on Houston St."

This claim seems to have been worked backward from where the limousine needed to be for McLain to be in the correct position for the acoustic evidence, not an objective evaluation of the photographic evidence.

This earlier frame of the Hughes film shows that at the time that the Presidential limousine was approximately in the position of microphone 2(9) that car number 7, the National Press pool Chevrolet blue-gray sedan, had just made the turn onto Houston. McLain doesn't make the turn until car 10 is in the middle of the turn. In fact there are several frames after this frame of the Hughes film, a stop in the film, and then 20 more frames before McLain comes into view in the Hughes film. And even when McLain first comes into view he would not yet be in the position that Bolt Beranek and Newman call "M".

Although Bolt Beranek and Newman's claims appear dubious, the methodology of tying the position of the Presidential limousine in the Hughes film and the Zapruder film may be useful as a check of our earlier determination that the frame in which McLain is first visible in the Hughes film is approximately Zapruder frame 138.

Part of the difficulty here is the fact that there is a break in the Zapruder film while the Presidential limousine is making the turn in the Zapruder film, and a break in the Hughes film after the Presidential limousine turns the corner and before McLain comes into view. We can use the same methodology the Thomas used concerning the velocities of the cars in the visible frames to determine the likely time that has passed while the camera's were not filming.

Below are the best estimates of the positions of all the vehicles in the Hughes frames.

If we compare the position of car number 7, the National Press pool Chevrolet blue-gray sedan, at Hughes C with it's position in Hughes D, we can see that it has moved approximately 16 feet over the course of 20 frames of the Hughes film. That is about .8 feet per frame. Since car 7 was near the middle of the stretch on Houston we will assume that it's speed was relatively constant and that it was traveling approximately this same speed during the time between Hughes B and Hughes C when the camera stopped filming. Between Hughes B and C, car 7 traveled about 25 feet. 25 feet divided by .8 feet/frame means the break in the Hughes film is approximately 31 frames long.

This means there were approximately 51 Hughes frames between Hughes B and Hughes D. While the Presidential limousine is not visible in Hughes B, the rear of the Presidential Secret Service car is still visible. Both cars turned the corner pretty close together so the position of the Presidential Limousine can't be to far in front of the Secret Service car as indicate on figure Hughes B.

Next we turn to the Zapruder film.

In the 24 Zapruder frames between frame 133 and frame 157 the Presidential limousine has traveled approximately 21 feet. This can be verified by observing the Limousine's position relative to a woman who was standing on the north side of Elm Street watching the parade. There are two women wearing white scarves over their heads, in Zapruder frame 133 the right front corner of the Presidential limousine is in line with the woman on the left. In frame 157 the Limousine has traveled its length as the woman in the scarf on the left to the limousine is now in line with the right rear corner of the limousine. The Presidential Limousine was 21' 3" long. So between Zapruder frame 133 and 157 the Limousine averaged .8854 feet per frame. Assuming 18.3 frames per second that is 11 miles per hour.

The preceding diagram compares the Presidential limousine's position at Zapruder Frame 133 and at Hughes B. The limousine has moved approximately 40 feet, and if we assume that the limousine was moving at the same speed as it was between Zapruder frames 133 and 151 then the limousine would cover that distance in 45 Zapruder frames. That would mean that Hughes B would be the equivalent of Zapruder frame 88. We have already determined that Hughes D is approximately 51 Hughes frames after Hughes B, so to get the Zapruder equivalent of Hughes D we would have to add 51 Hughes frames to Zapruder frame 88.

Most cameras made during that era ran between 16 and 18 frames per second. Watching the Hughes film at either of those speeds it is difficult to determine which speed looks more "natural". If we assume the Hughes film ran at approximately the same 18.3 seconds per frame as the Zapruder film, we can add the 51 Hughes frames directly to the 88 Zapruder frame and determine that Hughes D is equivalent to Zapruder 139. If we assume the Hughes film was running only at 16 frames per second, the 51 Hughes frames would be the equivalent of 58 Zapruder frames and Hughes D would be the equivalent of Zapruder frame 146.

Both of these numbers are very close to the earlier estimate we made that Hughes D was the equivalent of Zapruder frame 138. Considering the fact the Presidential Limousine was just coming out of the turn on Houston and Elm at Hughes B, it is possible that it was still accelerating between its position at Hughes B and Zapruder frame 133. If that were the case the limousine's velocity between Hughes B and Zapruder 133 might be lower than its average velocity between Zapruder frame 133 and 151. The result would be that it would take more Zapruder frames to get from Hughes B to Zapruder 133 so the estimate of Zapruder frame 88 being the equivalent of Hughes B would be reduced and the Zapruder equivalent of Hughes D would be reduced by an equivalent amount.

For example let's assume the limousine was only traveling at 10 miles per hour between Hughes D and Zapruder 133, 10 miles per hour is 14.67 feet per second, and assuming 18.3 frames per second it would take 50 frames to travel 40 feet. Hughes B would therefore be the equivilant of Zapruder frame 83 insted of Zapruder frame 88. The Zapruder equivilant of Hughes D would now be Zapruder 134 or 141 depending on the speed of the Hughes film.

Assuming earliest estimate that Hughes D is the equivalent of Zapruder frame 134 that would only give McLain 52 Zapruder frames or 2.84 seconds to travel the minimum of 180 feet that is needed to place him in the correct position to record the shots in Dealey Plaza. That means McLain would need to travel an average of 43 miles per hour down Houston. Even given a margin of error, this does not appear to be a reasonable assumption, so the photographic evidence does not support the acoustic evidence.

For a more complete evaluation of the positions of the vehicles as they traveled through Dealey Plaza see my motorcade animation.

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