I figured that I would take a step into mode dial settings. I was discussing it with a fellow patron of the B&B the Wife and I stayed at to see the eclipse. He asked for some pointers and I gave him what I could in the short time we saw each other. The discussion went to the mode dial and how to use it.
Most of the time I use Aperture priority (A or Av). I like to have control of depth of field. This is again a personal preference, and just one corner of the triangle. If it doesn't work for me then I usually jump to Manual. I put together this image to illustrate the difference.
All were shot at 400 iso in jpeg from an a57 with a 28mm lend mounted on a small tripod. Each time I went up a full stop (smaller number smaller in focus area) in the aperture and in turn the shutter went up a full stop too, to compensate for the light change. The difference between all of them is how much of the keyboard is in focus. The aperture controls depth of field and is a great tool to isolate what we want in focus in an image. It is also good for low light situations as well. If you are in one you can open it wide which allows more light in a shorter period of time. Such as a birthday party when the candles are lighting up a face, with a wide aperture you can have other people blur away if you know what you are doing. Go out and shoot.