The Bahtinov focussing spikes are detected automatically, allowing for a quantification of focus quality (movie):
You can also point your webcam with its original lens to an image of Bahtinov spikes to test:
or test it on a set of three dark artificial lines, by checking the “dark lines ona lighter background” checkbox:
Or even point it at a movie in your browser (from YouTube for example) to see it track focus live:
