There is a note on the Sigma web site under compatibility with the Sigma 50-500mm that states the following regarding use of the 1.4. *2 When the Tele Converter is attached, the zoom range will be restricted to between 100mm to 500mm. So am I reading this right? the only thing the converter will do is not allow the lens to go down to 50mm and it won't let it go over 500mm??? so why get it for this lens? :? or am I reading that wrong?