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Chris Davidson

Swan-Song -- Math Rules

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The equation broken down for those who don't want to do the conversion:

15.116ft- Distance from limo front to JFK in limo

divide

12 - Total frames from 154-166

=1.259666…. ft per frame

x

18.3 - Frames per sec

= 23.05ft traveled in 1 second @ 18.3 frames per sec

divide

48 frames per sec true camera speed at this point

= .48 ft per frame

x 5 frames (z161-166)

= 2.4ft = distance between JFK and Connally in limo.

= 5 true consecutive frames from a 48fps film.

Added on edit: I use 1.47ft per sec (rounded off from 1.466) as my multiplier for mph conversions.

chris

Edited by Chris Davidson

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Bravo Chris....

The 5 48fps frames from 161-166 shown at 18.3fps is effectively hidden and removes the wide turn onto Elm.

With these calcs we can find where the film switches from 48fps to 18.3 and back - yes?

btw - the limo's lights going on and off can be seen in Jeffrie's film. It does not seem to me the lights blink once they turn on Elm...

Edited by David Josephs

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Chris, I follow you up until your last post. If I understand your analysis, you are assuming that frames 154-166 were recorded at 18.3 frames per second but that 161-166 were recorded at 48 frames per second.

What am I missing?

Thanks

Ollie

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Chris, I follow you up until your last post. If I understand your analysis, you are assuming that frames 154-166 were recorded at 18.3 frames per second but that 161-166 were recorded at 48 frames per second.

What am I missing?

Thanks

Ollie

Bravo Chris....

The 5 48fps frames from 161-166 shown at 18.3fps is effectively hidden and removes the wide turn onto Elm.

With these calcs we can find where the film switches from 48fps to 18.3 and back - yes?

btw - the limo's lights going on and off can be seen in Jeffrie's film. It does not seem to me the lights blink once they turn on Elm...

David,

There are three known splices in the film. Probably a good place to start. The 157 splice is the only part I'm concerned with for now, as it sits in between z154-z171.

The 48/18.3 ratio may not be as important in trying to determine the film switches. It might be the 18.3/5 = 3.66 x 133 = 486. Depends on whether a repeating

sequence was used or was it random.

I want to keep my explanation (for now) limited to the equation provided and branch out from there. I hope those interested will gain a better understanding using this method.

chris

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Chris, I follow you up until your last post. If I understand your analysis, you are assuming that frames 154-166 were recorded at 18.3 frames per second but that 161-166 were recorded at 48 frames per second.

What am I missing?

Thanks

Ollie

Ollie,

The limo travels at the same speed regardless of what camera(with different fps) films it.

The limo travels 2.4ft in 5frames according to the extant zfilm.

18.3/5 =3.66 x 2.4 = 8.78 ft per sec = 5.98mph

That's why I broke down the limo speed in terms of ft per frame.

I was not the one that determined the zfilm ran at 18.3 fps.

Try this exercise, figure out the speed of the limo according to both CE884's (@ 18.3fps) Z161-166 and Z168-171 and add those two results?

chris

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The speed of the limo from z154-z166 is (23.05ft per sec) 15.68mph.

In 5 more frames up to z171, I will make the assumption it is traveling the same speed.

So, z154-z171= 15.68mph.

CE884 the orange version, z171-z185 = 17.18mph

CE884 the orange version, z185-z186 = 18.673 mph

The above speeds of the extant zfilm would appear to be more representative of what we see at this point in time.

chris

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The speed of the limo from z154-z166 is (23.05ft per sec) 15.68mph.

In 5 more frames up to z171, I will make the assumption it is traveling the same speed.

So, z154-z171= 15.68mph.

CE884 the orange version, z171-z185 = 17.18mph

CE884 the orange version, z185-z186 = 18.673 mph

The above speeds of the extant zfilm would appear to be more representative of what we see at this point in time.

chris

Average speed of 15.68 + 18.68 = 34.36mph/2 = 17.18mph = z171-z185 average speed

Average speed of 15.68 + 17.18 + 18.68 = 51.54 /3 = 17.18mph = average speed of z171-z185

chris

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The speeds determined for CE884 entries of z161-z166 and z168-z171= 2.24 and 3.74 mph respectively.

Their difference is 1.5mph, their sum = 5.98 mph inevitably linked to 2.4ft/5frames@18.3frames per sec

That difference equals the same difference in mph as the three previous tiers (over a 1 second time period).

18.68-17.18=1.5mph

17.18-15.68=1.5mph

Just doodling.

chris

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The WC had to make adjustments to the vertical as well. Start with this adjustment.

z161-166. What a coincidence.

10/12 =.83333 x 18.3 = 15.25ft

I hope you really didn't believe it had anything to do with vehicle heights.

chris

Mr. SHANEYFELT. Yes; because of the difference in the automobiles there was a variation of 10 inches, a vertical distance of 10 inches that had to be considered. The stand-in for President Kennedy was sitting 10 inches higher and. the stand-in for Governor Connally was sitting 10 inches higher than the President and Governor Connally were sitting and we took this into account in our calculations.

Mr. SPECTER. Was any allowance then made in the photographing of the first point or rather last point at which the spot was visible on the back of the coat of President Kennedy's stand-in before passing under the oak tree?
Mr. SHANEYFELT. Yes; there was. After establishing this position, represented by frame 161, where the chalk mark was about to disappear under the tree, we established a point 10 inches below that as the actual point where President Kennedy would have had a chalk mark on his back or where the wound would have been if the car was 10 inches lower. And we rolled the car then sufficiently forward to reestablish the position that the chalk mark would be in at its last clear shot before going under the tree, based on this 10 inches, and this gave us frame 166 of the Zapruder film.

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