You've probably had that time when you were trying to get of the focus, either in a studio setting, or for a video standup.
There's an app for that.
Focus Chart, an Android app, gives you a couple high-contrast focus patterns that will be easy to lock on, either manually or with auto focus. If you're trying to do a self-portrait or a video, put the phone with the chart on a stand where you're going to stand, set focus and then move it away and step in.
The best part is, it's free, and there's also a version for the iPhone as well.
