Quote Originally Posted by HDNitehawk View Post
@Joel; I tried the 1.4 III versions a while back, and really didn’t see much difference in IQ. In sharpness the III version made the 500mm less sharp in the center and a just a shade sharper on the edges. Overall I didn’t think it was a worthy upgrade, in fact no upgrade at all, and I sent it back. I wasn’t completely convinced I had a good copy.
But doesn't that make sense? Reports are that a 1.4x produces acceptable IQ (it may be a little worse, but it is acceptable). Additionally, reports say that the IQ degradation of the 2x II is unacceptable. Therefore, you are not going to get much of an improvemnet on the 1.4X III since there was not that big of a hit on the IQ with the 1.4X II to begin with... so there was not as much room for improvement. But the oppisite is true of the 2X III, where the 2X II left a lot of room for improvement so it would be easier to see a difference if they brought the 2X III up to acceptable IQ.