This presentation is based on a report prepared for Kodak and submitted to the Assassinations Records Review Board. The Kodak report is now in the possession of the National Archives who are responsible for its control and distribution. Permission was granted for me to make this technical presentation on the image capture characteristics of the Bell & Howell Model 414PD 8mm roll film camera to the MMS. The Model 414PD camera was used by Abraham Zapruder to film the assassination of President John F. Kennedy. It is the intention of the National Archives to make the full report public in the near future - possibly including distribution on the World Wide Web. This handout therefore provides only a brief synopsis and outline. -Roland J. Zavada, 10/24/98
Objective: This study resulted from a request of the Assassinations Records Review Board to Kodak, to conduct film tests using a Model 414 PD Bell & Howell Zoomatic Director Series camera to determine whether the recognized anomalies in the Zapruder film held by the National Archives are borne out by actual tests.
Introduction
Just after noon on November 22, 1963, Mr. Abraham Zapruder, a woman's clothing manufacturer, climbed onto a small concrete pedestal in Dealey Plaza with his 8mm movie camera. After President Kennedy's motorcade came into view and passed, Mr. Zapruder's 26 second film record of the assassination became the most significant amateur recording of a news event in history.
The Bell & Howell 414PD 8mm camera was, in 1963, a top of the line, high quality 8mm amateur movie camera. The optics were outstanding, the drive mechanism provided consistent long-run exposure time/per wind, the automatic exposure mechanism was of award winning design that yielded excellent results and the camera had a power zoom lens. The "P" in the model reference stood for "Power Zoom" and the "D" for "Dual Electric-Eye." The image formed within the standardized projectable area had no flaws or faults. Why then have we made an extensive study of the camera's image capture characteristics?
The camera used is not untypical of several models that position the film with its claw moving in an aperture cutout area adjacent to the image forming picture area. Consequently, scene information falls into this unmasked area due to the excess (circular) imaging area produced by the lens. For normal home movie projection this additional recorded scene information would be of no consequence as the projector aperture would hold back or mask-out this area.
We have the typical camera aperture area (i.e. the images that would be viewed by standard projection), and an additional area where the image extends into the area between the perforations and adds to the total scene content. To some students of the assassination, the Zapruder original film contains several image anomalies - almost all being related to the scene information recorded or imaged into the area between the perforations. (See sample frames below shot in Dealey Plaza.)
There is great significance attached to this area by various researchers who speculate that the anomalies may represent not the peculiar optics of Zapruder's Bell & Howell camera but rather, evidence of film alteration. It is important, therefore, to understand how the camera optics record images in this area and why certain anomalies are present - which is part of the objective of this study.
Overview of Image Anomalies:
The image characteristics that have been identified as "those of concern" are inconsistencies; i.e. they are not the same density, color and quality as those contained in the primary image area. The cause of those inconsistencies thus provides a focus for our review of camera characteristics. A look at a few frames from the Zapruder "in camera" original, provide a "picture" of the image characteristic that will be the bases of detailed discussions. (See Photo from the Warren Commission Exhibit.)
Claw Shadow -Between the perforations there is a broad bar where the image has more density (darker) than the primary image area.
Claw or aperture Flare - Sometimes adjacent to the dark (claw shadow) bar and between it and the primary image is a "streak" lighter than the dark bar and the adjacent image.
Multiple Exposure Areas Adjacent to Perforation - Sometimes there appears a lighter image area resembling images of perforation holes.
Ghost Images - Sometimes there appears to be "ghost" images such as a motorcycle fender. These are real images, which because of the design of the claw cutout area occur simultaneously above and below the perforation holes of the primary image being formed.
First Frame Overexposure - Occurs in the Zapruder original with his first exposure of the motorcade and at least twice in his filming of the first half of the roll. The possible causes of the fogged or lesser density first frame are reviewed, to the best extent possible - recognizing the limitation that we could not conduct a practical test with the Zapruder B&H 414 PD camera.
The camera mechanism includes a negator spring motor drive which, when
released by a pivotal movement of a control
arm from its position (by pushing down on the start button),
serves to rotate a scroll gear to drive a worm (gear). This worm serves
to rotate a film footage indicator dial, and to rotate a gear carrying a crank
pin to oscillate a shuttle or film pulldown claw and rotate a shutter,
as well as drive a governor, and to rotate gears. The shuttle is
urged by spring (pressed against the film) toward feeding
engagement with the film (i.e., to engage the perforation holes) in a
position between an aperture plate incorporating an exposure aperture (area)
and a pressure plate (to hold the film flat and motionless during exposure).
The shuttle is pivoted on a pin. The gear also carries a known disc
segment type of shutter which covers the aperture during frame-by-frame
feed of the film and when the camera is stopped.
Film Intermittent:
Camera Aperture:
Shutter/Exposure Time:
Motor/Governor:
Film Velocity/Frame Rate:
Evolution of Standards to Higher Frame Rates: It has been acknowledged that Bell & Howell's and Eastman Kodak's engineering practice for cameras moved toward 18 fps in the late 50s, and that this velocity was not uncommon in USA practice. The committee action to change standards takes time. The published standard for camera velocity in use in 1963 issued in 1954. Standards reflect practice and the evolutionary change to the higher frame rate of 18 frames per second was subsequently recognized in American National Standards that issued in October of 1964 , for Camera and Projector Usage - PH22. 21 and PH22.22. Bell & Howell testing confirmed that the Zapruder camera operated at slightly faster than 18fps - meeting the requirements of the revised standard.
Varamat Zoom Lens:
The 3: 1 zoom lens of the 414 camera series had eleven elements and reported to be of excellent quality. That quality position was confirmed in correspondence from the former Director of Engineering of the Optical Division, Mr. Rudolf Hartmann. He related: "the Varamat had an unusually flat resolution curve across its picture format (9 field position, 3 focal lengths, full aperture), yielding more than 60 lp/mm (line pairs per millimeter) resolution. Visual (air-image) resolution was 225 I/mm min. at any test position."Any attempt on my part to provide details on the lens or the zoom mechanism would be redundant. Dr. Cox and Mr. Mellberg confirmed that their patents, Cox #3074317 and Mellberg #3059533, are directly applicable to the 414 camera series.
"Windows" of the Lens:In simplest terms the entrance window of a lens defines the area of the object we are looking at; and the image in the lenses following it is called the exit window, since this defines the area of the image seen. To determine if the exit window size varied, the aperture plate was removed and a light was imaged through the lens onto frosted acetate to observe (as close as possible to the film plane) any change in exit window size with changes in focal length. We observed that there were changes. Although the full exit window remained almost the same, the effective illumination area changed by the presence of dark peripheral rings at the wide angle through normal lens setting. These dark rings began at a diameter slightly greater than the image area diagonal. (See drawing and photos on cover page.)
Electric Eye and Iris Diaphragm:
An article, A Direct Drive Automatic Iris Control, by LaRue, Bagby, Bushman, Feeland and MacMillin was published in the September 1958 issue of the SMPTE Journal and gives the reader design and engineering details on the automatic exposure system. The exposure sensing is achieved by feedback from two photo-voltaic (Se) cells, one sensing overall scene illumination and the other sensing paraxial luminance for backlight compensation. (Hence the "D" in 414PD relates to dual electric eye.)The iris diaphragm in the 414 camera series uses two overlapping disks each of which has a wedge shaped angular slot. The intersection of the two slots forms the variable aperture. Gear teeth are formed on the periphery of the disks that engage a gear mounted on the meter coil. (See drawing below.)
Unusual Iris Shapes:
Because the cut of slots in the two iris blades are not linear (as shown), unusual patterns can be formed as seen from the series of photographs of aperture openings. The subject of iris patterns and its effect on the resulting image is well documented in the literature on optical physics. Its significance here is the question of whether or not the possible unusual patterns yielded image artifacts. If the subject is not in focus inversion, multiple images, etc. can and do occur. However, if the image is focused properly, the iris pattern makes no difference. The question presents itself - are Mr. Zapruder's images in focus? By examination they appear to be. Did an unusual iris pattern contribute to any of the artifacts seen? In my opinion, I doubt it.
Recognized Image Anomalies in the Zapruder Original Film
Image Penetration
between the Perforations:
The telephoto lens setting consistently produces the maximum image penetration into the perforation area;
Normal lens focal length produces some but not full penetration into the perforation area; and
Wide-angle lens focal length produces the least penetration into the perforation area.
Claw Shadow
One of the image anomalies seen is a darker (higher density) band or wide bar in the image area between the perforations. This anomaly can be noted in the Zapruder frames as well as my practical test, photos. This higher density (band or streak) can be explained as being caused by the shadow of the intermittent claw (and its supporting arm) as it moves upward over the film to engage the following perforation and pull down the next frame. The pull-down is with the shutter closed, but the upward movement of the claw out of the perforation, over the area between the perforations, into the next perforation hole is done while the shutter is open and the film is being exposed. The claw movement over the area between the perforations reduces the amount of light reaching the film causing more density. (Less light is more density on a reversal film.) The reduction in exposure to the area behind the claw is not linear. The claw functions with a shutter crank pin engaging the claw slot giving a sinusoidal time relationship to the pulldown ratchet reentry action.Claw or Aperture Flare:
Claw flare appears to be a very real image anomaly often, but not always, seen adjacent to the dark bar caused by the claw shadow and the normal image area. In addition, when the 8mm image is viewed normal, the bottom of the upper perforation may show some flare-like density difference. It is this perforation that "sees" the bottom of the claw arm as it enters the perforation hole and pauses before beginning its rapid positioning stroke. (See also cover photo.)
Multiple Exposure Areas -
Perforation-Like Images
Ghost Images:
First Frame Over-Exposure:
The first frame of advance motorcade scene shows an over exposure condition, known as "first-frame-overexposure." In my discussions with M.E. Brown, former Manager of the 16mm and 8mm Department at Eastman Kodak, the condition was undesirable and a development/design problem to be avoided, but a not uncommon occurrence.Mr. Zapruder's camera appears to have been prone to the problem. The Secret Service copies of his family pictures show two other occurrences of first frame over exposure. With my test cameras, I had one, #3, that consistently had a noticeable first frame over exposure by about one-third of a stop. We were not given the opportunity to run a practical test with Zapruder's camera to determine if the first frame artifact was a consistent problem or unique to the assassination film roll.
Conclusion
It is my conclusion that all the inter-perforation image anomalies identified can be explained by the design and image capture characteristics of the Bell & Howell 414PD Camera.
Comments will be forwarded.
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Clint Bradford