I've only read this, but my understanding about parallax is it only causes a problem if you do not line up properly behind the scope. (Most people do not). I am sure I cannot as well. The problem is not that the focus is off, it is that you are not looking straight thru the lenses and so you're kinda like looking thru the surface of lake water and getting a distorted view of the target. If you can be certain to look straight thru the scope, you won't be so far off.

plus what Bill and AlleyCat said. :)