Sample variation is excessive with super zoom lenses ...
  Yes, though things have got so much better since the free for all production rush of ten + years ago ..... two out of three new lenses I bought had to be returned for de-centering faults, it was a veritable plague, I only bought from sites which had a fourteen day return no questions asked.
 When Sigma started their new Art/Contempory series they promised better accompanying quality control, which gave a kick up the butt to others.
