Trask, in his Pictures of the Pain, discusses the camera typically used for TV news motion pictures. The workhorse camera was a Bell and Howell Filmo 70, a 16mm format capable of filming at various speeds but normally at 24 frames per second. There are plenty of photos and films showing Darnell, Couch, and many other cameramen using this model of camera. The camera features a lens turret holding up to three lenses. Thus, the cameraperson could readily select an appropriate lens for a given scene. I don't know if those lenses were standardized throughout the news stations and Trask does not indicate what lenses were used by either Darnell or Couch. Film from the DCA shows Darnell's camera had at least two lenses, while a third could be present but is blocked from view.
Someone in a different thread (Thomas?) asked if the focal length of Darnell's camera was known.
Fortunately, knowing the film frame field of view (FOV, degrees) and image size (h, mm) of a standard 16mm frame we can calculate the lens focal length (f, mm).
FOV=2*atan(h/2f) or solving for f , f=h/2tan(FOV/2)
https://www.edmundoptics.com/resources/application-notes/imaging/understanding-focal-length-and-field-of-view/The FOV can sometimes be determined by matching the image details to a 3D model, or a map with sufficient detail, once the location of the camera is also determined. The image size for standard 16mm film is 7.49mm height x 10.26mm width, for an aspect ratio of 1.33. For the purpose of using the given formulae above the frame width h=10.26mm.
https://commons.wikimedia.org/wiki/File:16mm_and_double8_and_8mm.png I modeled the various scenes in Morissette's combined Darnell frames, with the following results. Note that the frames with Sitzman and the three women Jacob, Holt, and Simmons have aspect ratio of 2.36 ? indication of significant cropping of the vertical dimension. The scenes in the table were analyzed in the order they appear in Morissette's compilation as of 20190408.
Subject FOV degrees Focal Length, f mm
TSBD doorway.........................38 15*
Reflection pool/Buses...............38 15
Altgens, Newmans...................19 30
Fort Worth Sign, Knoll..............19 30
TUP, Bus.................................19 30
Rail Yard..................................?
Stockade fence, Retaining wall...21 30.6**
Infield.....................................38 15
Jacob, Holt, Simmons................38 15
Sitzman Interview.....................38 15***
*Couch also used a 15mm lens on his Filmo camera (38 degree FOV) for his scene coincident with Darnell's doorway scene.
** Uncertainty determining an accurate camera location for this scene gave values slightly high.
***The scene with Marilyn Sitzman was very likely filmed before Darnell filmed Jacob, Holt and Simmons, imo. I base this on placing Darnell very near the Zapruder/Sitzman pedestal for her interview. In a frame of Tina Towner's film at the Sixth Floor Museum web site I see, (with borderline pariodilia) upper bodies of Sitzman, her interviewer (Bill Wiseman per Denis' reply #3 this thread) and a man to his left. Shortly after Darnell films the Sitzman interview he pops out from behind the Stemmons sign and hustles eastward towards the three women to then capture their images.