Quote: A Pentax 50mm Macro does 1:2
The Pentax FA and DFA 50s give 1:1 macro enlargment.
A true macro is indeed 1:2 or better, as others have said. Macro lenses also offer much lower distorsion figures, are generally more evenly sharp across the frame than regular lenses, are usually almost as good wide open as they are at smaller apertures. They SHOULD (and I can testify that my FA 50 does) give amazing contrast. They offer a long focus throw for precise focus control.
Generally speaking, the macro lenses are the best at most things. They come at a price for a reason.