The first image comes from the HSCA analysis and they have the SBF happening at about Z190 but modern Scholars have the SBF occurring as Kennedy emerges from behind the Stemmons sign from Zapruder's POV.
Just to quibble a bit, but both men were hit while JFK was behind the sign but didn't react until both men were in full view. The timepiece, which is Zapruder's camera, shows us 1/18 second slices of time doesn't allow greater precision than that, but I feel confident in saying the shot struck +/- within one frame of Z222.
