Nikon Z 1.4x and 2.0x Teleconverters Review

Nikon Z Teleconverter Focusing Performance

You’re working with less light when you use a teleconverter, and the focus performance of your camera system may suffer as a result. It gets worse in low-light environments, especially when your maximum aperture drops to narrow values like f/8, f/11, or even smaller.

In the field, I clearly noticed that the focus tracking speed dipped with both teleconverters, especially with extreme combinations like the 2.0x TC with an f/5.6 or f/6.3 lens. That isn’t a surprise, but I wanted to put some numbers to my experience by measuring focusing speed in the lab. Here’s what I found on two different lenses, with each table arranged from fastest to slowest results.

Nikon Z 70-200mm f/2.8 (at 200mm) Focusing Speed

Nikon Z 100-400mm f/4.5-5.6 (at 400mm) Focusing Speed

Focus Speed and Accuracy Analysis

You’ll certainly lose focusing speed by adding either of these teleconverters, and the 2.0x TC has more of a slowdown than the 1.4x TC. Technically, though, the biggest decider of focusing speed is not whether you’ve used a teleconverter. Instead, it’s the maximum aperture of your setup and the level of light in the environment. However, by cutting down on the light by one and two stops respectively, the 1.4x and 2.0x TCs inevitably harm focusing speed.

That’s why the Nikon Z 70-200mm f/2.8 pairs well with both teleconverters, even in low light conditions. The maximum apertures of f/4 with the 1.4x TC and f/5.6 with the 2.0x TC are still usable except in the dimmest of environments. However, the Nikon Z 100-400mm f/4.5-5.6 is a different story. With that lens, the teleconverters give you maximum apertures of f/8 and f/11, which simply isn’t enough to focus quickly in low light.

As for focus accuracy, I noticed no issues even in the most challenging conditions (given a static subject). Nikon really nailed the focus accuracy of their mirrorless cameras. Keep in mind, however, that focusing speed is inseparable from focus accuracy if your subject is moving quickly! With a fast-moving subject, you’re almost certain to get out-of-focus results with, say, the 100-400mm + 2.0x TC combo in low light.

One side note. You may have noticed that the Nikon Z 70-200mm f/2.8 focused more quickly than the Nikon Z 100-400mm f/4.5-5.6 in most of the tests above. Although that’s true, it needs some context before you declare the 100-400mm to be a slow focuser. Specifically, the 100-400mm has a much longer focus throw than the 70-200mm; it’s almost a macro lens at 400mm. Since my tests involved racking focus from the minimum focusing distance, the 100-400mm’s times are longer even though its focus speed is very fast.

Chromatic Aberration

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.

Here’s an example of the Nikon Z 70-200mm f/2.8 VR S at 70mm, where it has low levels of chromatic aberration – around 1 pixel at all apertures (shown in blue in the chart below). Chromatic aberration measurements from the 1.4x TC are in red, and the 2.0x TC measurements are in green:

In the case above, both teleconverters increase the amount of chromatic aberration. However, it depends on the exact aperture you’re using – at narrow apertures, the 2.0x teleconverter is adding about a full pixel of additional chromatic aberration. Elsewhere, both TCs add about 0.5 pixels.

Here’s another example, this time with a lens that has a bit more chromatic aberration in the first place – the Nikon Z 100-400mm f/4.5-5.6 VR S. In the chart below, the “560mm” entry refers to the 1.4x TC, and the “800mm” entry refers to the 2.0x TC:

Once again, the teleconverters are adding about 0.5 pixels of chromatic aberration to our lab measurements, with the 2.0x TC looking a bit worse than the 1.4x TC.

Vignetting

The teleconverters do not add any appreciable vignetting to your lenses. In fact, they often improve it. Here’s an example from my tests of the Nikon Z 100-400mm f/4.5-5.6 VR S:

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

Distortion is not very important for most of the sports and wildlife photographers who will be shooting with teleconverters. That said, both of the teleconverters change the distortion characteristics of the lens you’re using.

In my tests, both teleconverters added some pincushion distortion to the Nikon Z 100-400mm f/4.5-5.6, cancelling out the inherent barrel distortion of the lens:

With the Nikon Z 70-200mm f/2.8 VR S, my results were similar. The 1.4x TC had 0.38% barrel distortion at 280mm, while the 2.0x TC had -0.23% pincushion distortion at 400mm. (This is compared to 1.93% barrel distortion of the bare lens at 200mm.)

Bokeh

To my eye, the bokeh when using either Nikon Z teleconverter was not as good as the bare lens. The teleconverters add a bit of a “donut” shape to out-of-focus specular highlights, drawing some unwanted attention to the background. It’s a bit worse on the 2.0x TC compared to the 1.4x TC. Here are a couple of examples with crops.

1.4x Teleconverter

2.0x Teleconverter

Sharpness

Let’s take a look at the sharpness of these two teleconverters in various situations. Teleconverters always lose some degree of sharpness – the question is how much.

It’s not as simple as saying that you lose so-and-so-% sharpness across the frame, or X amount in the center and X amount in the corners. Instead, the sharpness you get with a lens + TC combination depends on how they interact. With some lenses, you will lose a greater amount of sharpness from a TC than with others.

With that in mind, here are my results in the lab.

1. Nikon Z 70-200mm f/2.8 VR S at 70mm

The Nikon Z 70-200mm f/2.8 VR S is one of the sharpest lenses we’ve ever tested in the lab (even including prime lenses), so it makes a great test case for the two teleconverters.

The lens is sharpest at 70mm, so I wanted to test it as a best-case scenario with both TCs. I should mention, it doesn’t make a lot of sense to use a teleconverter when your zoom lens is at the widest setting – you’ll get better image quality by removing the teleconverter and just zooming in. But for testing purposes, it’s pretty revealing how the TCs interact with such a high-performing lens.

First, here’s the bare lens at 70mm:

I then added the 1.4x teleconverter, turning the lens into a 98mm lens with a maximum aperture of f/4:

And then I switched to the 2.0x teleconverter, making a 140mm lens with a maximum aperture of f/5.6:

The Nikon Z 70-200mm f/2.8 lens started out incredibly strong, so this is a good example of what you lose with each of the teleconverters. The 2.0x TC is worse than the 1.4x TC, but the results are usable with both TCs. In fact, the 1.4x TC results are actually quite sharp – better than plenty of lenses we’ve tested before.

By way of comparison, here’s how the bare lens performs around the same two focal lengths, specifically 105mm and 135mm:

That goes to show what I said a moment ago! If you’re using a zoom lens, try to avoid using a wider focal length plus a teleconverter. You’ll get better results by removing the teleconverter and zooming in instead.

2. Nikon Z 70-200mm f/2.8 VR S at 200mm

For a more relevant real-world test, I also wanted to look at the Nikon Z 70-200mm f/2.8 at 200mm – since you’ll usually be zoomed in as far as possible when using a TC. First, here’s the bare lens:

Next, here’s the result with the 1.4x teleconverter:

And here’s the result with the 2.0x teleconverter:

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.

Compared to the 70mm test that I showed you a moment ago, the biggest difference at 200mm is that the corners are weaker with both TCs. You can trace that result directly to the bare lens at 200mm, where it has worse midframes and corners than it does at 70mm. Teleconverters tend to exaggerate issues that are already present in a lens, and this is no exception.

3. Nikon Z 100-400mm f/4.5-5.6 VR S at 400mm

The Nikon Z 100-400mm f/4.5-5.6 VR S is an excellent lens, but the maximum aperture of f/5.6 is not nearly as forgiving as f/2.8. Also, this lens has good sharpness at 400mm, but not record-setting like the 70-200mm f/2.8 VR S. So, I wanted to see how it fared with both teleconverters.

Here’s the lens on its own at 400mm:

Now we’ll add the 1.4x teleconverter, resulting in a 560mm lens with a maximum aperture of f/8:

And then using the 2.0x teleconverter, for an 800mm lens with a maximum aperture of f/11:

This time, the sharpness results are clearly worse, as expected. The results are still usable, but even the best-case scenario with the 1.4x TC is essentially “f/16-level sharpness” – fine in many cases, but nothing groundbreaking. Meanwhile, at 800mm with the 2.0x teleconverter, the results are acceptable in a pinch. But if I shot at 800mm constantly, I would definitely want to add the Nikon Z 800mm f/6.3 to my bag.

Again, keep in mind that this is due to the lens/teleconverter interaction and any loss of sharpness here is not just because of the teleconverters. The Nikon Z 100-400mm f/4.5-5.6 simply isn’t a great choice to pair with the 2.0x teleconverter, in large part because of the f/5.6 maximum aperture.

On the next page of this review, I’ll cover a question that many photographers were asking me before this review: Is it better to use a teleconverter, or better to crop the photo from a bare lens? To see my tests, click the menu below to go to the next page, Compared to Cropping.