Quotes from Julie Adair King

Adjust the viewfinder to your eyesight. This step is critical; if you don't set the viewfinder to your eyesight, subjects that appear out of focus in the viewfinder might actually be in focus, and vice versa. If you wear glasses while shooting, adjust the viewfinder with your glasses on — and don't forget to reset the viewfinder focus if you take off your glasses or your prescription changes.