Many professional photographers adjust their camera settings manually. Things are a bit more difficult for newbies though. The Focus Shifter can help. This is a nice tool that gives you more creative control and enables you to produce better work with your camera. It has a handle that adjusts your focusing ring and a marker to help you track where you want to focus. You can even use clips to set hard stops.
The Focus Shifter lets you use a dry erase marker to keep track of focal points. With this tool, you can shift focus without taking your eyes off your subject. It fits any lens up to 98mm. Sets you back $49.