Quote Originally Posted by dave_whatever View Post
And because it's flat and doesn't benefit from the gearing of a knob scale it's much less precise, especially with wide lenses. Not to mention it can be lost, dropped, or forgotten. But each to their own.
It also compensates for image ratios which many knob types don't and then you get the wrong results. And, you can always download another one. Once you forget it it becomes much more unlikely that you would forget it again.