Or, they could simply print the four from a movie negative.  
 
Kodak had a camera that could do 1000 frames a second in the early 30's.  
But a regular movie camera at 24fps will just capture 4-5 frames of a swing if the .2 of a second swing time I've heard is correct.  
 
 
It's hardly old, but I have a camera that takes four sequential pictures on the same frame. Plastic and cheesey, and a bit too slow for baseball. But still kinda cool. 
 
Steve B
		 
		
		
		
		
		
		
		
		
	
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