Like I pointed out above, forget about trying to get this teleconverter to focus on Nikkor lenses. On Sigma lenses, however, it is a different story. Although the AF speed and accuracy decreased a little, the combo worked even in low light situations. I was able to focus with the 120-300mm + Sigma 2x TC on the D3s in my living room that was lit with just a single 100 Watt light bulb! There were a couple of focus errors here and there, but it worked out quite well overall. On the negative note, the AF reliability seems to go down at distant subjects (towards infinity). NIKON D7100 @ 600mm, ISO 800, 1/500, f/5.6 Sharpness, Contrast and Color Rendition

Works with FTZ-adapter: NO, don’t try it! The protruding glass elements of the TCs will not fit into the FTZ-adapter and you may damage the optics. Would have been nice to use all F-mount lenses via FTZ-adapter on the new Z TCs – but no. [-] The lens is stellar and may be the perfect telephoto if you don’t need a zoom. (After using it I was reminded that I do need a zoom). Nikon has nailed it with a perfect balance of compact size, sharpness, and relatively large aperture. You can’t get f2.8 unless you are rich and a body-builder (or only shoot from a hide or vehicle), but most people can carry this lens and get 2/3 stop faster aperture compared to an f5.6 zoom. One oddity is that it has Vibration Reduction but no switch on the lens to turn it off (done in camera menu). Desert Floor as Seen from Six Miles (10 km) Away, 2:23 PM, Thursday, 10 November 2022. Nikon Z7II, Nikon Z 400mm f/4.5 VR with Z TC 2× teleconverter (making this an 800mm lens) wide open at f/9 hand-held at 1/ 250 at Auto ISO 64 ( LV15.0), Radiant Photo Software to cut through the haze. bigger or full resolution. Some lenses look great on paper and on test charts, but cannot perform equally well when used in an outdoor environment, especially with fast-moving subjects like birds. The primary reason is autofocus, the performance of which depends on many different factors. Teleconverters generally negatively impact autofocus performance, due to a considerable loss of light and contrast and the 2x TC is the worst in this regard. Adding a teleconverter slows down lenses and the Nikon TC-20E III slows down by two full stops. What this means, is that when the teleconverter is mounted on an f/2.8 lens, it slows down to f/5.6 and as you may know, autofocus performance on small apertures beyond f/5.6 is unreliable even in broad daylight conditions. Nikon clearly points out that autofocus does not work beyond f/5.6, so if you have an f/4.0 lens, forget about autofocus – you will have to resort to manual focus.

The teleconverters come with a pouch that’s just as flimsy as the pouch of the Z lenses and has no strings to pull it close. [0] Image stabilization, auto focus, additional functions: Everything works as expected as the teleconverters don’t interfere with the functions and features of the attached lens. EXIF data for focal length and aperture are adapted and the identifier for the lens also reflects the use of TCs. Even the display of the Z 70-200mm f2.8 VR S shows the correct values for aperture and focal length. [+]

I use the names TC-20E and TC-20E II throughout the text interchangeably. They are the same product. Used with a great lens, of course it's ultrasharp; sharper potentially than the air through which we shoot. Not bad! The biggest sharpness robber here are atmospheric conditions and the fact that these palms are not lying in the same plane, so most of them are simply out of focus.

Distortion

TC-14E III: 70-200mm f/2.8G or f/2.8E, 70-200mm f/4G, 200mm f/2G, 300mm f/2.8G, 300mm f/4E, 400mm f/2.8G or f/2.8E, 500mm f/4G or f/4E, 600mm f/4G or f/4E One benefit that people don't realize about teleconverters is that the minimum focus distance stays the same. If you do a lot of very close telephoto work (e.g. hummingbirds in blind shots), there may be an advantage to using something like the 300mm f/2.8 with a TC. First, the 300mm is quite tolerant of converters, but to the point: focus distance stays at 2.3m, meaning you could have a 600mm equivalent that focuses down to less than eight feet. TC-20E increases focal length by 2x and lowers maximum aperture by two stops. The original version was marked AF-I, a second version (II) AF-S, and then it was redesigned optically to create the current TC-20EIII. Unfortunately, no! Many years ago, you might have been able to buy a generic teleconverter that would work with all lenses sharing that camera mount. However today lens mounts have far greater electro-mechanical complexity. Different aperture controls and AF systems means that teleconverters aren't just specific to camera brands, but that they will only work with specific lenses, too.