>>6251928when you use live view you're probably using the video function right? use the magnification button to zoom in a little and use the manual focus to get sharp.
remember this: the more light you have, the more shallow the depth of field will be. the less light the more you'll be able to get into focus.
if you open up your aperture your subject will be more in focus that the bg. to keep both in focus but retain light you need to stop down and then play with the ISO and shutter speed to still allow a good amount of light in while not flooding the picture with light