As far as the possibility of a shot at 190, it's not just the blur analysis and eyewitness evidence that places the first shot at this time, but the photo analysis. One of the most overlooked facts about the case is that the HSCA photography panel concluded a shot rang out before Kennedy went behind the sign...and that they came to this conclusion before the acoustics panel came to their conclusion a shot at Z-190 was probable.
Dave Powers said Kennedy jerked off the side of the car when hit. Kennedy's head and arm movements as he heads behind the sign suggest he was hit at this time. His movements at this time certainly don't look natural. And the failure of Dale Myers etc to acknowledge this and to insist he continued calmly waving at this time is perplexing, to say the least.
The first point is about Jiggle/blur analysis of the Z-film.
You would not disagree that only a very loud noise would cause such blur/jiggle.
You would also agree that, according to the vast majority of ear-witnesses, only three clearly audible shots rang out.
But would you agree that more than three instances of blur/jiggle during the Z-film makes the use of this analysis to determine when shots occurred completely redundant?
Another observation of the HCSA panel was that JFK 'froze' before going behind the Stemmons sign.
This is not shown in the Z-film.
The 'biggest' revelation was that JFK made a startling head turn to his left just before passing behind the Stemmons sign.
This has been completely refuted in this thread. JFK made no such head turn.
This leaves you with witnesses like Willis and Powers but I will hold up witnesses like Brandt and Templin who are absolutely adamant the first shot hit Kennedy after the limo had passed their position.
This rules out a first shot at z190 as does JFK's reaction to being shot as seen in the Z-film.