How do you all think the Kenko Pro 300 1.4x tc is compaired to say a Sigma or Tamron 1.4x tc? I cannot afford Nikon's 1.4 and I've heard the nikon is very picky about which lenses you can use on it anyways so I've decided to look at the alternative brands. However, from what I've heard, the Tamron is the most compatible but the Sigma has better image quality but only works with AF-S lenses, where the Kenko is the best of both worlds? Or am I somewhat off track. I will be using my 70-200 2.8 Sigma and maybe a Nikon 300 f4 (non af-s).
the 300 f/4 the school owns cannot AF with a 1.4x on it, very accurately, on even the D1. its not even worth buying one if you intend to ever use it with an f/4 lens.
My Kenko Pro 300 1.4x works pretty well with my Nikkor 300 f/4 AF-S. It is all-but-unuseable on my Sigma 120-300 f/2.8, but it works pretty well with the other lenses I've tried it on.
The Sigma TC's work very well with the Sigma lenses they are made for (not all of them- see compatibility list), but I never succeded in combining a Sigma TC with another lens.... A colleague of mine has a Kenko TC and is using it with Nikkor and Sigma lenses, even keeping AF above f5.6 on a D70 in some cases. Sigma TC's do not allow AF above f5.6.
The Kenko Pro 300 or whatever it is does AF with non AFS lenses from what I have heard. The Nikons will not because they are missing the focusing screw. I don't know about the Sigma or Tamron TCs.
