use a tripod. Set camera for manual focus and manual adjustment of exposure. Use the lowest F stop you can. If you are overexposed, lower the levels of your light. use a neutral density filter on your lens, or built in. increase the distance between your subject and your background. increase the distance between your camera and your subject and focus tight on your subject.
if all that doesn't work you need a different camera with a larger chip. Try a DSLR.
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