Modern cameras are ludicrously good at focusing automatically, able to lock on small targets and track them precisely and accurately through many challenging situations. These autofocus systems are not totally infallible, however, and there are times during which it is actually a better choice to switch to using manual focus. This great video tutorial discusses why you practice using manual focus and why it can be useful for your work.
Coming to you from Leigh The Snap Chick, this excellent video tutorial discusses the virtues of learning to use manual focus in your work. No doubt, that might sound a bit strange given how good modern cameras are, but they are not perfect. In fact, I still encounter situations in which autofocus fails me and I need to switch to manual focus. Luckily, most newer cameras offer an array of tools that make it far easier to find focus by hand. For example, I have my camera set up to automatically zoom in whenever I grab the focusing ring, and with that extra magnification, it is not particularly difficult to get things exactly where I want; in fact, I actually prefer to work this way sometimes. Check out the video above for the full rundown.
if you are holding your camera in your right hand, and you are eating a hot dog with your left, how do you accomplish manual focus
With your knees, silly.
can't use your knees if they're controlling the steering wheel
Fingertips.
Manual focus is my preferred method for street photography.
just remember, the autofocus is not just for speed; the autofocus is because computers are a lot better than people at most tasks, and they're normally a lot more consistent.
Depends how much time and effort you're willing to put in but there are a few techniques that if you can master them will help you to focus fast on a manual lens. Besides, I find for street photography nothing is faster than a pre-focused lens (and a deep depth of field). Often autofocus isn't quick enough and you can miss a split second moment. Just my opinions based on my own experiences though.
I switched to using the autofocus when I had to start wearing glasses. I couldn't trust them when I needed to focus quickly.