Excerpt: When you need a little extra reach, it's a valuable addition. Yes, you're better off with a longer prime, but for the rare occasions when I need it, I can add it to my f/2 200mm lens to create an f/4 400mm.
Excerpt: If you are a pro and looking for 2X reach, this is what you get. Don't listen to the whiners about 'autofocus hunting...' and soft images - use manual focus, stabilize yourself, avoid high iso and enjoy this fine piece of optics. EVERYTHING that is lacking is made up for in post.
Provides full lens function but with poor sharpness and contrast on 400mm F2.8 lens
J. Moomaw, Amazon
15 June 2015
Summary: I really wanted this to work, and based on some of the positive reviews I was hopeful. However I found it was worse than nothing on the long lens I wanted to use it with. I'm giving it two stars vs. one because it allowed the camera and lens to work properly.
Excerpt: Tried this converter once before on my 300mm f/2.8 VR II and was not satisfied. Decided to try another copy. Same results. Image quality and focusing took a big hit. Cropping the 300 with TC14E II attached produced much better results. Returned it.