This is a great book by a Mr. Bryan Peterson
Make sure you get the latest edition (currently Aug.2010).
Bryan has a an easy going writing style packed with tons of real examples.
It’s not a very long book (~175 pages) and there are lots of great example photos filling up nearly every page.
It is highly rated on Amazon… only $20 with shipping.
Basic takeaways for my own future reference:
We then balance all three of those in our “Exposure Triangle”…
For one example, starting with the desire to have full focus on a long view (e.g. big field of flowers), we select a high f/stop. If it's a bright easy light day, we can leave our ISO low … lastly we move the shutter speed up or down until our camera’s light meter falls on ZERO.
I had never been clued in on that fundamental part about adjusting one or the other (aperture or shutter) in order to *move*the*light*meter* bar back to center zero. One typically does this looking through the viewfinder at the little gauge of vertical bars with 0 in the middle.
This was a pretty big revelation for me. Maybe I'm particularly clueless 🙂 and it's considered so obvious that it's not worth mentioning; but I also wonder how many people carry around multiple hundred dollar cameras without knowing this.
For an alternative example, if we want to capture that “blurry water” effect on a stream or a waterfall, we’ll start with a longer shutter to (e.g. 1/8 sec or even 1 full sec) and then move the f/stop to get the light meter to 0… the f/stop will be high in this case (perhaps even f/32) because a long shutter is a long exposure to light and therefore a correspondingly small opening is necessary to counteract that light washout (i.e. overexposure).