NOTE: Joe used the DVD release of IMAGE OF AN ASSASSINATION: A New Look at the Zapruder Film for this analysis. -Clint Bradford

Just for the record, I don't make my living in the field of photography. Rather I get paid to program and support computers, lately seeming to spend much of my time cursing and shaking my fist at them. :-) My interest in photography is strictly amateur. My only camera is an old Speed Graphic (4x5) that I shoot black-and-whites on that I develop and contact print myself. The optical concepts discussed below are basic and straightforward. Learning them is a necessity when you don't use a camera with auto-focus and auto-exposure.

Anthony Marsh claims that the continuity of ghost images between the sprocket holes makes it virtually impossible for frames to be deleted without detection. Related work by Roland Zavada demonstrate that the intersprocket image anomalies are the natural result of filming with a Bell & Howell 414PD camera, the model Zapruder used. David Lifton counters that the forgers simply re-filmed the altered Zapruder film with a camera like Zapruder's. I believe that the depth of field apparent in the film rules out David's scenario.

Depth of field is the range of distances that are in focus to a camera for a given set of lens settings. With the settings required by David's scenario, anything farther than 3-4 feet should be in focus. The bush next to Zapruder that appears in later frames is out of focus even when the stationary background is relatively sharp. The center of the bush is about 6 feet away from Zapruder.

Beginning at Z385 and continuing until Z449, the branches and leaves of a large bush next to Zapruder partially blocks his view of the limo on Elm. (Anthony Marsh informs me it is a shrub called pyracantha.) You can see this bush on page 57 of Groden's The Killing of a President immediately to the left of the man peering over the fence. On page 195 is a photo the FBI took from Zapruder's pedestal during their recreation which shows the bush although somewhat trimmed. The Ciccone and Trask maps place the center of the bush about 6 feet from Zapruder. Zapruder panned over the top of the bush. The higher branches near the middle would be the ones that could extend up into the frame.

The following frames best show the difference in focus between the bush leaves and more distant objects. Stationary objects are the sharpest in them which means motion blur from camera panning is at a minimum. This increases the likelihood any blurring of an object is due more to optical effects than motion effects.

In these frames, notice that the leaves of the bush are soft and indistinct with little to no detail even though the image size of the leaves are large in the frame compared to the leaves of the trees in the background. For the following observations, I used the MPI Images of an Assassination DVD. The lack of focus in the leaves becomes especially apparent in the closeup versions of the film such as Medium Frame.

Remember that the later frame numbers in the Image of an Assassination (IOAA) video are 2 less than the corresponding Zapruder frame. All the numbers in this article are the standard Zapruder frame numbers. Just subtract 2 if you look for them on the IOAA video.

Z405, Z413:

The leaves of the bush are soft in focus compared to the more distant lamppost, sign, and man in background.

Z416:

The leaves of the bush are not in as sharp of focus as the leaves of the overhanging tree and the lamppost.

Z427, Z429, Z431:

The letters of the distant FORT WORTH TURNPIKE sign are sharp, yet the leaves on the bush's closer branches are not.

Z435, Z444, Z445:

The reddish leaves on the tree in the background are much sharper than the leaves of the bush.

To determine the camera's depth of field (DOF) requires knowing the focal length setting of the lens (amount of zoom) and the f-stop of the iris.

FOCAL LENGTH
David Lifton proposes that the forgers re-filmed their altered Zapruder film through a camera identical to Zapruder's, and thus recreated all the optical idiosyncracies of that model camera such as the ghost images between the sprocket holes. One can imagine the forgers projecting the altered image on a life size screen, aiming the camera at the screen, and capturing the image. Since the forgers must exclude any detail that reveals the new the film to be a copy, they must zoom in on a central area that excludes the original's edge markings, ghost images, and perforations.

All indications are that the image on the existing Zapruder film were filmed with the camera set to maximum zoom, the Telephoto setting of the camera. Not only does the angle of view support this, but also the fact that the images extend so far into the inter-sprocket area. If the forgers filmed at Telephoto, and they zoomed in on a smaller area of the original frame, then Zapruder would have had to film originally with the lens set to a wider angle. How much wider must it have been?

The forgers have to zoom in enough such that they fill the camera's aperture with image. In effect, the full height of the aperture, including the cutout area for the claw must fit in the main image area of the frame. The aperture height at the claw cutout is 6.68 mm, and the height of the normal picture region is 3.68 mm. The focal length at the camera's Telephoto setting is 27 mm. The reduction in focal length is then 27 mm * (3.68 mm / 6.68 mm) or about 15 mm.

The Wide Angle setting on the camera is a focal length of 9 mm and the Normal setting is 13 mm. So, Zapruder would have had to film at a setting slightly longer than Normal for the forgers to be able to pull this off.

F-STOP
The second value to determine is the f-stop. The f-stop indicates the amount of light the lens and iris are sending towards the film. Zapruder used film with a speed rating of ASA 25 (Kodachrome II). Zapruder's camera had an "electric-eye" that automatically opened or closed the iris depending on light conditions. The film appears properly exposed, so we can assume the f-stop was close to optimal.

The rule-of-thumb in photography is that with the iris set to an f-stop of f16, and on a bright sunny day at noontime, the shutter speed should be set to the ASA rating of the film. If the electric-eye had the iris at f16, then, the shutter speed should be 1/25th of a second. The shutter speed was fixed at 1/40th of a second on Zapruder's camera, so the iris would have been open more than f16. It would be closer to f11 for brighter scenes. (As the lens opens to let in more light, the f-stop number decreases.)

I conducted tests with a light meter on 12/1 near Chicago at 12:30 PM with a clear sky. Facing south and metering a variety of scenes, the readings were around f11 plus or minus 2/3ds of a stop.

Readings of a gray card with the card facing the sun read f11-2/3. With the gray card blocking the sun so its surface was in shadow read f5.6.

The lens of Zapruder's camera was likely at f11 for the brighter scenes and perhaps opening up towards f8 as more shadowed objects filled the frame when he aimed towards the underpass.

The Zavada Report includes depth of field charts for the camera. Camera manuals often include these so you know which ranges of distances are going to be in good focus for the different lens settings. I listed the near distances only. The far distances were usually at infinity. When reading the table, keep in mind that for the forgers to be able to alter the film in the way Lifton suggests, Zapruder would have to have his lens set to a focal length of around 15 mm, a tad more than the Normal setting. The f-stop would have been between f8 and f11. The distance listed in the table, in feet and inches, is the closest an object can be and still be in focus. If it is closer than that, then it will be out of focus. Zapruder aimed over the top of the bush; the branches high enough to extend into the frame were about 6 feet away from him.

This table formats right with a fixed pitch font.

                      FOCAL LENGTH
            9 mm         13 mm         27 mm
F-STOP   Wide Angle      Normal      Telephoto
------   ----------      ------      ---------
f1.8       5' 5"         8' 9"         15'
f2         5' 2"         8' 5"         15'
f2.8       4'            6'10"         14'
f4         3'            5' 4"         12'
f5.6       2' 2"         4' 2"         11'
f8         1' 7"         3' 1"          8' 9"
f11        1' 2"         2' 4"          7'
f16          10"         1' 8"          5' 8"
f22           7"         1' 3"          4' 5"

If Zapruder had the lens set to a 15 mm focal length, and with an f-stop between f8 and f11, anything farther than 3 to 4 feet away from the film in his camera would be in focus. Since the nearby bush, 6 feet away, was not in focus when the background objects were, it indicates Zapruder must have set the lens to a longer focal length than 15 mm. This precludes the possibility of the forgers re-filming through a B&H 414 PD camera as Lifton suggests. One cannot modify depth of field by making copies of a film since it is the result of passing a 3-dimensional image through a lens.

Since the film was not re-shot zoomed-in to exclude the original edges, it follows that the edge markings, ghost images, claw shadow, and claw flare are from the original film. Anthony Marsh's analysis of the sequence of ghost images, then, authenticates the frames and rules out the possibility of missing frames (other than the known splices.)

The lack of focus in the leaves is consistent with the lens set at Telephoto. From f11 to f8, the near distance ranges from 7' to 8'9", which would put the middle of the bush just outside the depth of field. The bush seems wide enough that some of the farther branches should appear in focus. Because Zapruder shoots over the bush, we don't have a good view of the bush's far side. One frame that appears to show a far branch is Z429. It is by the lower right corner of the street sign. The branch is in silhouette with the bright street behind it, but the outlines of the leaves and branches are more distinct and they don't get burned out by the surrounding bright street like some of the other leaves earlier in the sequence did. These signs of sharper focus of the far branch suggest the depth of field boundary is somewhere within the width of the tree.