GARY MACK SAID:
I can explain the latest alteration theory du jour. In fact, anyone familiar with the physics of photography should know the answer.
The claim is that Zapruder frames 214, 218, 220, 224 and 229 show problems with the edge of the Stemmons sign.
In 214 [pictured below; click to enlarge], instead of showing a sharply-defined curved line, the upper rounded corner seems to disappear. In the other frames, the objects beyond the sign seem to show through the straight edge of the sign and sort of blend in with it.
The explanation is very simple. There are actually five variables at work in every frame: a moving camera, a moving car, moving objects, a stationary sign, and a relatively slow camera shutter speed. All the moving objects travel in the same direction left to right.
The shutter speed of Zapruder's camera was 1/40th of a second (http://jfk-info.com/durn1.htm) and the film passed through the camera at an average rate of 18.3 frames per second. During the time each frame was exposed, 1/40th of a second, all the objects except the sign moved a short distance laterally. Beginner physics say the stationary sign, therefore, must appear more blurred than the moving objects. And it does.
The objects (limo sun visors, Jackie and others), appear through the blur because they move with the camera while the shutter was open. Zapruder's camera shutter speed wasn't user-adjustable, but if it were, faster and faster speeds would show decreasing blur of the sign, and all sign corners and edges would appear normal.
So what are we actually seeing in each frame? Exactly what one should see. Bright objects in the car show through the blurred corner and side of the sign, distorting the image and obscuring the edges. Nothing more.
If anything, the anomalies support the film's authenticity, which is something I've been saying since 1998, long before The Sixth Floor Museum received the film's copyright (http://assassinationscience.com/mack.html).
And if anyone wonders if my continuing defense of the film has something to do with my employment at the Museum, they should think again. Absolute proof of conspiracy would dramatically boost interest in the assassination and attendance at the Museum. That would be wonderful, but conspiracy needs to be proven first.
DAVID VON PEIN SAID:
Excellent, Mr. Mack. Thank you.
And I'd be willing to bet that very similar explanations concerning the various "anomalies" in the Zapruder Film [like the explanation discussed by Gary Mack above] could be presented in order to debunk every single one of the claims made by the conspiracy theorists who have attempted to discredit the authenticity of the film.
And I still can't see how Doug Horne (or anybody) can find a way for the film to be altered (especially on Day 1, November 22nd), because we know that Abraham Zapruder or his business partner were IN POSSESSION OF and IN CONTROL OF Zapruder's camera-original film throughout that entire day.
We know that Zapruder himself was present when his camera-original film was developed. And Zapruder was also present when the three first-generation copies were made. There was simply no time available to "fake" the original film prior to the three first-generation copies being made.
Do the alterationists actually think that the film-forgers were able to fake (in perfect tandem) not only the camera-original film, but also ALL THREE first-generation copies that were made within HOURS of when the original film was developed?
It makes me wonder if Mr. Horne actually thinks that Abe Zapruder and Erwin Schwartz were a part of a "plot" to alter the film. But I really don't want to shell out more than $80 for Horne's five volumes of fantasy in order to find out. Maybe he'll tell me himself sometime during one of our heartwarming and tender encounters at Amazon.com. ;)
David Von Pein
December 23, 2009