I found a written transcript of Gary Stover's lengthy interview of Mary Moorman on May 24, 2011. And as I'm reading through it, this is the first thing that jumped out at me:
This is a photograph, here again, is a copyrighted photo, and we give credit to the Sixth Floor Museum and Texas School Book Depository for its use tonight. This is a frame from a movie, the most famous home movie ever made, done by Abraham Zapruder, a 26.5 second film which chronicled basically the whole sequence of events shots in Dealey Plaza that day. I've selected a frame from this which shows Mary Ann and her friend Jean Hill, Mary Ann in the blue and Jean Hill in the red. This, according to the Zapruder chronology of frames as it exists, this corresponds to frame #298 I believe which places it roughly one second prior to Mary's photograph. So, I want you to understand that I am not trying to match up Zapruder's exact time sequence with Mary's here, this is just to show Mary, Mary Ann in the position to take the photograph and its one second before Mary snapped her own photograph.
So, Gary simply wanted to show a picture of Mary taking her picture, and he like many others, chose Z-298.
But, he adds that, though he selected that frame to depict Mary taking her picture, that she didn't actually take it then, that she didn't take her picture until a full second later. But, what happened during that full second? The limo moved forward, and now the Kennedys were past her. And she didn't move; she didn't even turn. So, why didn't she take her picture then? In the Z-film, we see her poised and ready to shoot the Kennedys starting at Z-292. So, why didn't she press the God-damn shutter? Answer: She did. Gary was more on the money than he realized. That IS when Mary took her photo. But, her photo wasn't the one we call the Moorman photo.