• Check if you are in Manual Focus Mode.
  • Make sure you do not move when pressing the shutter button
  • Check that the shutter speed is not too low.
  • Check if the distance between the subject and the lens is smaller than the lens' minimum focus distance.
  • Check if you have selected the proper focus point when focusing the subject.
  • Check if the AF illuminator is obstructed.
  • Check if there is obstructing object while you shoot, such as a screen window or fence.