Understanding Exposure starts with the basics, describing the concept of ‘exposure value’ and explaining the relationship between aperture and shutter speed. The author, Bryan Peterson, then moves on to talk about exposure under various lighting conditions (front-lit, side-lit, back-lit, low-light and night). He gives excellent tips on how to meter (use the sky, usually).
He also talks a bit about aperture and depth of field. In fact, depth of field is the backdrop to much of his discussion of selecting aperture values.
I learned quite a bit from this book. I guess there was no really ‘new’ information in it, but the practical advice clarified a number of points for me. I recommend this book to any amateur photographer who wants to get better first-time exposures.