Video of Illuminations - Auto Focus or Manual?

[PSUGuy]

In some of my WDW vids of fireworks from the early 2000s I apparently had the camera set to auto focus with the result that there was a lot of blurring as the unit refocused between near and far explosions. More recent vids are not so bad but I'm wondering if, for best results, just get a wide enough shot to catch the whole area and set it to manual? If it's not already obvious let me admit that I'm a rank amateur with any sort of camera and I'm using a Samsung HMX-F90M, new in 2014.

Thanks,
Bill From PA