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Author Topic: Tom C. Dillard Exhibits C and D  (Read 317 times)

Online Charles Collins

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Tom C. Dillard Exhibits C and D
« on: April 22, 2019, 05:58:43 PM »
What are the distances from Dillard's camera to the sniper's nest window? Dillard's testimony indicates that he believes it was at least 50 to 60 yards. But it would be nice to verify this. I am thinking it is feasible to calculate the approximate distance based on the field of view of the 100mm lens for exhibit C, and the field of view for the 35mm lens for exhibit D. I know the angle of inclination of the camera will complicate this. However, as much as everything about this case has been studied over and over again, I would hope that someone has already done this. Does anyone know of a study like this?

Offline James Hackerott

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Re: Tom C. Dillard Exhibits C and D
« Reply #1 on: April 24, 2019, 05:05:48 AM »
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What are the distances from Dillard's camera to the sniper's nest window? Dillard's testimony indicates that he believes it was at least 50 to 60 yards. But it would be nice to verify this. I am thinking it is feasible to calculate the approximate distance based on the field of view of the 100mm lens for exhibit C, and the field of view for the 35mm lens for exhibit D. I know the angle of inclination of the camera will complicate this. However, as much as everything about this case has been studied over and over again, I would hope that someone has already done this. Does anyone know of a study like this?
Charles,
I'll try to answer basically in the reverse of your questions. I recently did a study to determine the various lens focal lengths used for Jimmy Darnell.
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For Darnell I determined lens focal lenghts by comparison of the film's field-of-view imagery versus a 3D model. For Dillard we have the focal lengths, but I need the equivalent fields of view for the 3D model software.   

Lens focal length, image field of view and image size are related by the following equations. Knowing the lens focal lengths (f, mm) and image size (h, mm) the frame field of view (FOV, degrees) is determinable.

FOV=2*atan(h/2f) or solving for f ,   f=h/2tan(FOV/2)
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The image size for standard 35mm film is 36mm x 24 mm, for an aspect ratio of 1.50. For the given formulae above the frame width h=36mm.

Dillard took two photos while his car was paused in front of the TSBD. First he used the 28mm lens to capture much of the south TSBD face. He followed up with his second camera equipped with the 100mm telephoto, aiming near the 6th floor corner window. After the car began to move forward he captured a third image of motorcade vehicles heading towards the triple underpass, also with the 100mm lens.


Summarizing the data:

Scenes were rendered with the 1.50 aspect ratio of 35mm film with the calculated FOV. Notice that both of these two frames in Trask's Pictures of the Pain were cropped. The 28mm image on the left was cropped from the right edge. The 100mm frame was cropped bisecting the windows at frame left. Disclosure-since these frames in POTP are cropped I don't know exactly were was frame center. Thus, my renderings portray my best guess framing. The third image of the TUP was only used to determine aspect ratio showing it was not cropped..


Now, finally addressing your initial question Charles, I created a camera path using the 28mm lens that moves the camera from Dillard's position in the stopped car further away such that the perspective of the TSBD is fairly well maintained. The camera moves towards the TSBD from about 180 feet to 90 feet of line-of-site distance (camera to 6th floor corner window). Seemingly, one might be able to crop frames from anywhere on that path to give similar results to Dillard's photos. The results would be similar for the 100mm lens.

However, when viewed from above it is quite apparent that the camera is far to the west of the actual motorcade path, which should be sufficient to rule out Dillard's opinion he was 50-60 yards line-of-site to the windows. I would love to see the un-cropped photos.



James

JFK Assassination Forum

Re: Tom C. Dillard Exhibits C and D
« Reply #1 on: April 24, 2019, 05:05:48 AM »

Online Charles Collins

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Re: Tom C. Dillard Exhibits C and D
« Reply #2 on: April 24, 2019, 02:23:56 PM »
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Charles,
I'll try to answer basically in the reverse of your questions. I recently did a study to determine the various lens focal lengths used for Jimmy Darnell.
You are not allowed to view links. Register or Login

For Darnell I determined lens focal lenghts by comparison of the film's field-of-view imagery versus a 3D model. For Dillard we have the focal lengths, but I need the equivalent fields of view for the 3D model software.   

Lens focal length, image field of view and image size are related by the following equations. Knowing the lens focal lengths (f, mm) and image size (h, mm) the frame field of view (FOV, degrees) is determinable.

FOV=2*atan(h/2f) or solving for f ,   f=h/2tan(FOV/2)
You are not allowed to view links. Register or Login

The image size for standard 35mm film is 36mm x 24 mm, for an aspect ratio of 1.50. For the given formulae above the frame width h=36mm.

Dillard took two photos while his car was paused in front of the TSBD. First he used the 28mm lens to capture much of the south TSBD face. He followed up with his second camera equipped with the 100mm telephoto, aiming near the 6th floor corner window. After the car began to move forward he captured a third image of motorcade vehicles heading towards the triple underpass, also with the 100mm lens.


Summarizing the data:

Scenes were rendered with the 1.50 aspect ratio of 35mm film with the calculated FOV. Notice that both of these two frames in Trask's Pictures of the Pain were cropped. The 28mm image on the left was cropped from the right edge. The 100mm frame was cropped bisecting the windows at frame left. Disclosure-since these frames in POTP are cropped I don't know exactly were was frame center. Thus, my renderings portray my best guess framing. The third image of the TUP was only used to determine aspect ratio showing it was not cropped..


Now, finally addressing your initial question Charles, I created a camera path using the 28mm lens that moves the camera from Dillard's position in the stopped car further away such that the perspective of the TSBD is fairly well maintained. The camera moves towards the TSBD from about 180 feet to 90 feet of line-of-site distance (camera to 6th floor corner window). Seemingly, one might be able to crop frames from anywhere on that path to give similar results to Dillard's photos. The results would be similar for the 100mm lens.

However, when viewed from above it is quite apparent that the camera is far to the west of the actual motorcade path, which should be sufficient to rule out Dillard's opinion he was 50-60 yards line-of-site to the windows. I would love to see the un-cropped photos.



James


Thanks for the reply. And nice work! When I read Dillard's WC testimony of April 1, 1964:

Mr. DILLARD - The School Book Depository. And at the same time I brought my camera up and I was looking for the window. Now this was after the third shot and Jackson said, "there's the rifle barrel up there." And then he said it was the second from the top in the right hand side, and I swung t it and there was two figures below, and I just shot with one camera, 100-mm. Lens on a 35-mm. Camera which is approximately a two times daily photo twice normal lens and a wide angle on a 35-mm. Which took in a considerable portion of the building and I shot those pictures in rapid sequence with the two cameras.

I assumed that he took the 100mm lens photo first. But that isn't exactly what he said. Although the two men in the window below don't appear to me to show in the wide angle photo (might have moved away from the windows between photos). So it would make sense to me that the wide angle photo was taken after the 100mm lens photo. In any case, Dillard says that the two photos were taken in rapid succession.

By the way, is the 3D model of Dealey Plaza you used a creation of yours? I sure would like to have access to one for things like this.

Offline James Hackerott

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Re: Tom C. Dillard Exhibits C and D
« Reply #3 on: April 24, 2019, 07:04:41 PM »
Charles,
You're very welcome for my input to your question. I was using Richard Trask's Pictures of the Pain for reference, and he quite clearly puts the 28mm wide-angle lens as the first picture of the two. But since the two photos are on different film rolls the negatives wouldn't help with timing-but I'd still like to see them. Like you say, the images were taken close in time.

For the 3D model I'm afraid that is mostly my creation. Just this month (19th) marked 20 years since I made my first visit to Dealey Plaza for video to help with the modeling. VHS tape back then LOL! The program (POV-Ray) price is right ? FREE! It's described as a Scene Descriptive Language and features ray-tracing for modeling the lighting. It is all hand coding and over the 20 years I have probably written around 10,000 lines of code. Kinda my ?ship in a bottle? project. If you ever would like something modeled with it just give me a shout out.

James

JFK Assassination Forum

Re: Tom C. Dillard Exhibits C and D
« Reply #3 on: April 24, 2019, 07:04:41 PM »

Online Charles Collins

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Re: Tom C. Dillard Exhibits C and D
« Reply #4 on: April 24, 2019, 09:30:19 PM »
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Charles,
You're very welcome for my input to your question. I was using Richard Trask's Pictures of the Pain for reference, and he quite clearly puts the 28mm wide-angle lens as the first picture of the two. But since the two photos are on different film rolls the negatives wouldn't help with timing-but I'd still like to see them. Like you say, the images were taken close in time.

For the 3D model I'm afraid that is mostly my creation. Just this month (19th) marked 20 years since I made my first visit to Dealey Plaza for video to help with the modeling. VHS tape back then LOL! The program (POV-Ray) price is right ? FREE! It's described as a Scene Descriptive Language and features ray-tracing for modeling the lighting. It is all hand coding and over the 20 years I have probably written around 10,000 lines of code. Kinda my ?ship in a bottle? project. If you ever would like something modeled with it just give me a shout out.

James

That is a very cool creation. Thanks for the information. I have only been to Dealey Plaza once and for a brief time. But sometimes I feel like I know it better than my own backyard (from studying all the films and photos). Thanks for the offer. I might just take you up on it before long.

JFK Assassination Forum

Re: Tom C. Dillard Exhibits C and D
« Reply #4 on: April 24, 2019, 09:30:19 PM »

 

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