Nikon TC-301 (2x) Teleconverter AI-S

Keeping in mind that this super-expensive teleconverter was meant for use on prime lenses like the 300 f2.8, 400 f2.8 and the 600 f4, the performance of the 2 copies I own is simply amazing. On the 300mm f2.8 you get a 600mm f5.6, fast enough for most outdoor situations, and it is very difficult to see any drop in image quality, even on a 16 X 20 print. On the 600mm ED-IF f4.0 you get a 1200mm f8. This is a little more lens than most photographers (myself included) can handle comfortably, but the option is there if you're up to it. Contrast and resolution are better than my copies of the TC-14B, which is saying a lot.

Outstanding real-world performance. Easily worth the extra cost compared to any other Nikon converter on high-speed prime lenses. I have not used it on zoom lenses.

Price.

Most Canon EOS and Nikon converters

None needed or anticipated. Very solid piece of equipment.