23-08-2013, 07:05 PM
I spent some time last night reviewing discussions of the actual Z-camera. Zavada did not have much to say in his report other than reiterating claims by the manufacturer. But I did find the following confirmation of my opinions, tucked in a series of quotes Bill Kelly presented taken from Doug Horne's ARRB volumes:
"…(Brugioni) also said that the Secret Service was vitally interested in timing how many seconds occurred between various frames, and that Ralph Pearse informed them, to their surprise and dismay, that this would be a useless procedure because the Bell and Howell movie camera (that they told him had taken the movie) was a spring-wound camera, with a constantly varying operating speed, and that while he could certainly time the number of seconds between various frames if they so desired, that in his view it was an unscientific and useless procedure which would provide bad data, and lead to false conclusions, or words to that effect. Nevertheless, at the request of the two Secret Service agents, Ralph Pearse dutifully used a stopwatch to time the number of seconds between various frames of interest to their Secret Service customers. Dino Brugioni said that he placed a strong caveat about the limited, or suspect, usefulness of this timing data in the briefing notes he prepared for Art Lundahl. " P 1233
My story: Some time ago, friend had shot footage using a spring-wound 16mm camera, which ran slow, featuring several interviews which were audio recorded on DAT. It had been impossible to sync the footage in film form.Later, with a digital editing system, I found the opportunity to try and sync the footage. While expecting that I could deduce a simple formula by which to alter the speed of each shot, what I discovered was that the footage was constantly variable - a little faster, a little slower - throughout each individual run. This was, I realized, an effect of the spring wound mechanism of the camera.
So I'll stand beside Ralph Pearse with the observation that, because of the properties of the spring-wind mechanism of the camera, the Zapruder film is simply not reliable for any timing deductions whatsoever. It is not an accurate clock and so any counting of frames expecting to correspond to seconds or tenths of seconds of real time - not possible. Fascinating to see that the Secret Service was told this right away, and yet they just blundered on. Following orders.
I am of the opinion that the Z-film is accurate from 1st frame to last in sequence, but some masking may have been added to cover a back of head blowout.
I don't think a limo stop was removed because I believe the limo slow down is actually visible in the Z-film.
The anomalies I believe can then be understood as resulting with the camera are the quick frame-to-frame movements, such as Greer's head turn. The overall effect is pronounced because of the slow frame rate (18fps). I noticed similar anomalies when working with the footage discussed taken by my friend, (and when I timed the average frame rate for that camera, it was just over 18fps too). 16 or 18 fps are not ideal rates for the smooth perception of movement, (one reason why 24fps became standard), but became a consumer camera (8mm - Super 8mm) rate because, in part, it allowed for the 50' cartridges to run longer.
"…(Brugioni) also said that the Secret Service was vitally interested in timing how many seconds occurred between various frames, and that Ralph Pearse informed them, to their surprise and dismay, that this would be a useless procedure because the Bell and Howell movie camera (that they told him had taken the movie) was a spring-wound camera, with a constantly varying operating speed, and that while he could certainly time the number of seconds between various frames if they so desired, that in his view it was an unscientific and useless procedure which would provide bad data, and lead to false conclusions, or words to that effect. Nevertheless, at the request of the two Secret Service agents, Ralph Pearse dutifully used a stopwatch to time the number of seconds between various frames of interest to their Secret Service customers. Dino Brugioni said that he placed a strong caveat about the limited, or suspect, usefulness of this timing data in the briefing notes he prepared for Art Lundahl. " P 1233
My story: Some time ago, friend had shot footage using a spring-wound 16mm camera, which ran slow, featuring several interviews which were audio recorded on DAT. It had been impossible to sync the footage in film form.Later, with a digital editing system, I found the opportunity to try and sync the footage. While expecting that I could deduce a simple formula by which to alter the speed of each shot, what I discovered was that the footage was constantly variable - a little faster, a little slower - throughout each individual run. This was, I realized, an effect of the spring wound mechanism of the camera.
So I'll stand beside Ralph Pearse with the observation that, because of the properties of the spring-wind mechanism of the camera, the Zapruder film is simply not reliable for any timing deductions whatsoever. It is not an accurate clock and so any counting of frames expecting to correspond to seconds or tenths of seconds of real time - not possible. Fascinating to see that the Secret Service was told this right away, and yet they just blundered on. Following orders.
I am of the opinion that the Z-film is accurate from 1st frame to last in sequence, but some masking may have been added to cover a back of head blowout.
I don't think a limo stop was removed because I believe the limo slow down is actually visible in the Z-film.
The anomalies I believe can then be understood as resulting with the camera are the quick frame-to-frame movements, such as Greer's head turn. The overall effect is pronounced because of the slow frame rate (18fps). I noticed similar anomalies when working with the footage discussed taken by my friend, (and when I timed the average frame rate for that camera, it was just over 18fps too). 16 or 18 fps are not ideal rates for the smooth perception of movement, (one reason why 24fps became standard), but became a consumer camera (8mm - Super 8mm) rate because, in part, it allowed for the 50' cartridges to run longer.