Is there a way to know when we'd have a grossly out of focus background for a given condition? For instance, if I have a DOF of 2 feet, will the background be obliterated at 4 feet behind the subject? 6 feet?
By obliterated, I'm referring to a background that is obscured to eliminate distracting elements in a portrait situation. I realize that this is subjective.
I'm guessing above that there might be a rule of thumb regarding this.