Now I understand....
Yesterday I was shooting a charity event. One of the events was an indoor paintball range. I figured, what a great opportunity to get some good shots. Before I entered the range, I had to put on this goofy looking mask.
When I got in there, I swear half the people were aiming for me! Trying not to get hit and whatnot, I was taking cover behind barriers and obstacles.
The mask made it very difficult to focus. Couple that with it being inside, I was shooting my CZ 28/2.8 wide open on ISO 640, and still metering shutter speeds of 1/15 and 1/8. I took about 40 shots, then made an exit.
Upon review I'd say half of them were out of focus or blurry! ARGH.
Now I understand why Robert Capa's legendary pictures on D-Day were out of focus. I couldn't even imagine how difficult it was for him to compose and focus with his life in danger. At least for me, I just didn't want to get pelted.