Know your camera

There is no way I could have taken this picture had I not been totally familiar with my camera.  The impala suddenly leaped into action, and I had precious few milliseconds to react.  In fact, it happened so fast that I wasn't even sure I had focused on it correctly.  But my camera was set up for action since I was on safari, and that meant the exposure mode was on Program, the ISO was high enough to guarantee a fast shutter speed, and I used back button focus.  In addition, I had all the focus points selected.  Those settings enabled me to get this picture -- plus my quick reaction time.  I used the new Canon 100-400mm lens set to 400mm on a 7D Mark II body (giving me 640mm), 1/1000th of a second, f/11, and 640 ISO.