The fact that you bought a book to learn about what your camera is capable of shows that you are interested in more than taking simple snapshots. Understanding the fundamentals of exposure is very important when taking up the hobby of photography. While the scene modes are a starting point for taking photographs of different subjects, if you want to achieve predictable results then learning about exposure is where you need to start.
Exposure isn't exceedingly difficult to master, but at first, it can seem a bit technical and confusing, especially if you're new to the world of dSLR cameras. In this chapter, I break the concepts down to the basics, explain what they are, and the different uses that they have for creating artistic photographs.
Exposure is the amount of light that reaches the camera sensor during a single shutter cycle. A shutter cycle occurs when the shutter-release button is fully depressed, the reflex mirror flips up, the shutter opens and closes, the mirror flips back down into place, and the shutter resets. While that sounds like a lot, in reality it all happens in a fraction of a second (unless you're using a long shutter speed, of course).
There are three things that determine how ...