To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
but not the important details you need to know. For example, in focus shift, the most important aspect (where to set the focus initially) is not bothered with. So if you're not totally new to DLSR cameras, you don't need this book, you're better off with the manual that comes free or rely on good old Google for specific issues with the camera.