Adding either teleconverter to your lens will increase the level of chromatic aberration that you experience with most lenses. However, as usual, the exact performance depends on the lens + TC combination.

There is only one issue: The TC’s have to be dedicated to the lens because otherwise you end up with wrong setting of the AF fine adjustment. I have got one that is purely for the 500f4 G and the other one for “the rest”. And then I switched to the 2.0x teleconverter, making a 140mm lens with a maximum aperture of f/5.6: The story is extremely similar here – both teleconverters have a negative impact on sharpness, with the 2.0x TC being a clear notch worse. But as before, the 70-200mm f/2.8 is such a sharp lens that you have room to spare. Both of these results are still completely usable, and the 1.4x result in particular is quite good. The Nikon TC-14E III multiplies the focal length of your lens by 1.4×, and makes the lens one stop slower.

Nikon Z Teleconverter Focusing Performance

Similar to AF performance, lens sharpness, contrast and color rendition will depend on the lens the teleconverter is coupled with. When I used the teleconverter on the Sigma 120-300mm f/2.8 Sport, contrast and colors looked superb. Sharpness-wise, as expected, there is definitely a drop of sharpness across the frame, but it is not outside of specs or abnormal. As you will see from the below comparisons, the Sigma 1.4x loses about the same amount of sharpness in the center as the Nikon 1.4x TC. Because teleconverter compatibility is dependent upon lens use, the lenses that will work with a teleconverter are all FX lenses (those that are designed for use with the larger FX format image sensor or film SLR cameras. On the lists, the lenses marked "AF" will retain auto focus operation when used with a Tele Converter. The lenses marked "MF can only be used for manual focus. Some lenses will be operated AF even mentioned "MF", however, be aware that these lenses cannot focus precisely by auto focusing. Therefore, please use such lenses in MF mode when teleconverter is attached. As mentioned above, while teleconverters are typically made to work with more than one lens, there are no teleconverters on the market that work with every lens. Both Nikon and Canon have rather small lists of lenses (compared to the overall lens line) that are compatible with their teleconverters for a reason – most lenses are not designed to couple with teleconverters. It's just as sharp with the 2x teleconverter. You can see more fine details, even though the heat shimmer is magnified twice as much as the first image without the teleconverter.

As you can see, the maximum level of vignetting with the bare lens at 400mm is 1.17 stops. Meanwhile, the maximum level of vignetting with the 1.4x teleconverter is just 0.57 stops, and the maximum with the 2.0x teleconverter is 0.43 stops! My results were similar with the Nikon Z 70-200mm f/2.8. In short, you don’t need to worry about vignetting with either Nikon Z teleconverter. Distortion

I own the Siggy 120-300 OS and both the Siggy and Nikon 1.4 TCs. If you grind the extra tab off the Nikon TC it will fit on the Siggy. I believe it is sharper, but it communicates the wrong f stop and hunts a bit for focus. So Siggy on Siggy and Nikon on Nikon is the TC rule. Its power distribution is designed for lenses of large diameter. Without affecting the lens performance, it offers stable image quality until corners. The rich peripheral brightness enables shooting quality images at every focal length. Looking to upgrade your equipment? Get competitive prices on major brands with our part-exchange service.