And background focus is based on the ratio of distances between the camera and the foreground object and the background and the foreground object. The fstop values are meaningless without knowing that information.
I'd argue for a newbie this is very useful to explain the difference between the settings. It took me forever to figure these out with trial and error back in the 90's
Can you explain the difference then? I turn up ISO when I have to for low-light, but agree with the guide that the grain looks worse. I understand you may want stylistic grain, but I generally want clear photos and grain isn't that.
In this day-and-age of phone cameras and point-and-shoots, I can’t think of a single photographer that could actually control these setting who would need this graphic.