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Edited by John Dolva
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Edited by John Dolva
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Edited by John Dolva
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Hi John.

I believe you may need to factor in the fps [The official party line [18.3] vs what I have seen referenced as Zapruder's claim of a fully wound on 24 - which is odd - my B&H 414 doesn't have a setting for either speed]? In which case, if there are as many as ~6 frames that could be missing per second, you may be stuck deriving some form of range.

Plus the object you are using for your blur analysis may increase the difficulty of the problem you are looking to solve. If the 'blur' you selected in z330 is indeed a piece of skull which was ejaculated violently forward from a rear, flat, occiput shot fired from a high velocity deer rifle, you would need to guesstimate the size of the fragment to figure out the blur?

Just thinking aloud. z322 seems to have the best still 'shot' of what IMO is a skull fragment, lying on the grass. If it was the Harper fragment - I suppose you could get some measurements to use - but that's also an unknown?

- lee

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Thank you very much for that input, and you too Mark, it usually takes me a while to digest and see clearly what someone is saying. However at first glance, I dunno Lee, I think it's the relative characteristics of the blurs that are the key, Both blurs , on the car and the ground have lengths that seem to change proportionally from pair to pair, similarly angles seem to follow through in a consistent way. So the factors that are different from pair to pair is the relative angles eg 14 degrees in say frame 318 and roughly 0 in frame 313. and the length of the blur in x axis and in y axis.

ahhh i getyou lee, yes the size of the object would be a factor, the left of the blur doesnt correspond with the right edge. Hmm yes what size, I'll check the best showing least blur, thank's so much. i wonder though whether the original hypothesis of mine might be good still The different angle of the blurs in a pair, most noticable in frame 318 i think.

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Edited by John Dolva
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oops, heres the pic...

Mr. Dolva...I sent your blur analysis to Dr. Costella, your

fellow Aussie, who responded:

"The two blurs shown here are well known to me. One is a

specular reflection from that bright spot on the bubble top connection bar

on the limo. The other is a bright spot in the grass. They are moving at

different speeds ... about 8 mph different, according to the Z film. The

difference between the two blurs is precisely this movement of the limo

relative to the grass while the shutter is open."

I hope this helps your analysis.

Jack :)

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Jack hmmm that sounds more like a description to me. The camera moves too, the shutter speed is the same in all frames. It wouldnt matter if the blur on the car is from the reflection on the bar or from the antenna in the back. As Lee pointed out the 'spot' on the grass is an area with dimensions, so the dimensions would determine the actual length of the blur. How did Costello calculate * mph, was he just using the accepted speed as the way to state that that is the meaning of the difference between the blurs? I have issues with his points about the z film in general (names swimming in alphabet soup don't impress me much). Anyway, I'm grateful you took the time to do that, Jack. Perhaps as I think about what Costello had to say I'll see something that is hidden from me now. I think it is possible to formulate a general formula to determine the speed at any frame with blurs.

John

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John,

You've got an interesting idea here... I read your post a couple of days ago, and have been pondering it. Although I have no firm answers yet, there are a couple of things that come to mind.

1) The panning motion of the camera is non-linear. It is in the form of an arc. Technically, one must consider both angular velocity and linear velocity.

2) There is also the issue of angles involved. In this case, we have several known things -- linear distances between landmarks, frame-rate of the camera. However, angle of viewpoint and parallax needs to be considered when attempting to landmark a moving object with a moving camera against fixed points.

However, I don't think any of these are show-stoppers. Don Roberdeau's plot of DP is incredibly useful for such things, among other things.

Additionally, you have hit on another thing that I find interesting -- the use of the pixel as a unit of relative measurement. Of course there is the issue of projecting a 3D image onto a 2D surface. That is unavoidable. However, for relative measurements, the pixel might be useful. We know much about the optical characteristics of the Z-film camera -- including critical factors of focal-length, depth of field, etc.

Using this information, any object in the Z-film could be placed within a sphere (or cone) 3-dimensionally based upon its 2-d X-Y and relative focus. This might lead to some additional insight to the placement of various objects.

Regards,

Frank

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That's fantastic Frank, I think you understand the physics of this better than I, so I'd like to ask you some questions. Could difference in one of the movements, linear angular length over angular difference of blurs sine cosine tan or something else easily derived yield a constant that would be useful? John

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one thing that we know for certain is that the area on the ground is stationary in reality, so all movement is relative to it? right, does anyone dispute that the white blurred area suggested to be on the ground is on the ground and therefore effectively a fixed reference point?

Edited by John Dolva
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a further point, during the time that the shutter is open, the camera doesn't necessarily move in a consistent way, what I mean is that the camera may for example be almost stationary for a moment then move and that or any movement might be accelerating/ decelerating/ or whatever, so it is the difference in movement between the moving car and the stationary ground that to my thinking could yield results ???

for those who wonder about the usefulness of all this. If a universal technique like this can be shown to work then it can be used to check previous speed estimates, perhaps missing frames can be detected? the different films may be correlated and perhaps matched more accurately and forgeries detected?

hmm I just thought while writing the above. Single frame photos showing moving objects where blurs occur...why not use there as well?? are there photos that have been previously discarded for not being sharp enough that in fact can be shown to be most useful. anyone have a blurred photo of DP at time of assassination that otherwise might be ignored because of the blurring?

Edited by John Dolva
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