While it's true an image can't be sharp unless the subject is in focus, the converse is not necessarily true, that an image which is in focus, will necessarily be sharp. Image sharpness is fundamentally controlled by focus, but there are other important factors which enable in-focus images to be sharp.
In this multi-part series, we'll discuss what it takes to make a photograph look sharp. We'll look at how to successfully focus your camera on your chosen subject, and how to make your well focused image actually look sharp.
In Part I we'll look at how modern digital cameras autofocus (AF), and what factors influence AF systems' ability to focus quickly and accurately.