What is parfocusing?

Answer 1

parfocusing is when you zoom in first focus, then zoom out agian prior to taking your shot.

Example on a 24-70 lens, with 24 being wide and 70 being tight or zoomed in. go to 70 and press shutter half way, while still hold the shutter button halfway-zoom out again and take the shot. Not all lenses work this way but mines does.