No lens is better with a teleconverter. That said, you know I will plug the Nikon over anything else. It's even in my name, come on man. I have used the 200-500 for several years on a daily basis and I love that lens. I enlarge show prints to 20X30 that are tack sharp. The following are grab shots. Lets see some shots that compare from the Sigma. I DARE ANYONE, COME ON SIGMA FANS, MATCH ME, I DARE YOU.