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09 Oct 2021

Comparing the Fujifilm XF 16‑80 with the XF 18‑138 Travel Zoom Lenses

When I bought into the Fuji system, I selected the XF 18‑135 f/3.5‑5.6 R LM OIS WR as my main zoom lens. This is a lens with a very wide focal range, that is commonly called a “travel zoom” because you could travel the world with just this one lens. And indeed I happily did. In 2019, Fujifilm released a second travel zoom lens, the XF 16‑80 f/4 R OIS WR. Ever since, I have wondered how this new 16‑80 compares to my 18‑135. But given that these lenses are somewhat similar, few people on the internet were ever able to compare them side by side. This blog post will change that.

The 18‑135 has served me very well indeed. Of course it is not the world's brightest lens, nor sharpest, nor smallest. But so long as I can get the shot, these limitations don't bother me. Except for two things: The transition between in-focus and out-of-focus can be a bit rough, and my lens extends on its own when carried on a sling. My hope is that the 16‑80 has a nicer rendering, especially for people photos with out-of-focus backgrounds, and a stiffer zoom ring that doesn't creep.

Picture of Squirrel, with hazy bokeh
Instead of smoothly blurring, the near-focus areas of the 18‑135 have this strange, hazy look

Physical

Physically, the 16‑80 is a slight bit smaller (89 mm vs 98 mm) and ligher (440 g vs 490 g) than the 18‑135, but the difference is negligible on camera. If anything, the 16‑80 actually feels a bit bigger to me due to its larger front element. Some people claim that the 16‑80 feels better built than the 18‑135. To that end, the rings on my 16‑80 turn more smoothly than my 18‑135's, but then that is comparing a new-ish lens to a well-used one. Autofocus speeds are also reputably different, but they feel similar to me.

The 16‑80 has a numbered aperture ring that allows for adjustments while the camera is turned off. On the other hand, the 18‑135 can switch to and from auto-aperture without losing its preset aperture, which is useful as well. The ideal lens for me would have both the auto-aperture switch and the numbered aperture ring. Oh well.

A picture of the two lenses from the side, both collapsed and extended A picture of the two lenses from the front
Size comparison of the two lenses. The 18‑135 is a longer, and the 16‑80 wider. Note the marked aperture ring on the 16‑80, and the Auto-Aperture/OIS switches on the 18‑135.

The 16‑80 has a 72 mm filter thread, while the 18‑135 uses 67 mm filters. This is somewhat annoying for me, as my filters are all 67 mm, which also fit on my 70‑300. I'd imagine users of the 72 mm 10‑24 see this differently. Anyway, using a thin polarizer with a 72‑to‑67 step-down ring works without issue on the 16‑80. My inch-thick macro filter however does vignette heavily until 23 mm.

Rendering

In terms of rendering, I find the 16‑80 to have a gentler transition from in-focus to out-of-focus, and indeed render out-of-focus backgrounds more smoothly than the 18‑135. At the long end, the 16-80 is actually a useful portrait lens, which is an unexpected but welcome feature for my photography.

A picture taken with each lens, with a blurry background
Rendering of out-of-focus elements. Especially the points of light in the top right have an asymmetric crescent shape for the 18‑135, but blur smoothly for the 16‑80.

At the wide end, the 16‑80 exhibits some significant distortion. While the camera or post processing programs can easily correct this, it leaves the image corners stretched, and renders the 16‑80's nice round bokeh balls as ugly ovals. Thus large-aperture shots at the wide end can be somewhat problematic.

Resolution

Next, let's compare the resolution of the two lenses. To do that, I printed a test chart, and took some test images. All images were taken in identical illumination, on a tripod, with the chart covering half the sensor height/width. The following graphic shows a resolution scale near the center of the frame and near the left edge of the frame. And just for fun, I've thrown in a similar analysis from two prime lenses as well. The resolution scales are in 200x line widths per picture height. On my 6000×4000-pixel sensor, the theoretical maximum resolution would therefore be a resolution number of ⁴⁰⁰⁰∕₂₀₀ = 20. All test images are straight crops from original images, reproduced at their original resolution.

A grid of crops of a test chart, with various lenses at various focal lengths and f‑numbers
Comparison of lens resolution with a test chart. Each image is a direct crop at the X‑T2's native resolution. Resolution numbers in 200x line widths per image height.

Center images were focused in the center, and side images were focused on the side. A two-second timer was used to eliminate camera shake. Due to the geometry of my room and the size of my printer, all pictures were taken near the close-focusing distance of the lenses. A red line indicates the limit of resolution of these lines, as judged by my eyes. The corresponding resolution numbers are generally consistent with the ones published by opticallimits and lenstip1, albeit I judged them a bit more conservatively.

The results of this test are surprising to me: the 16‑80 is actually my sharpest lens. It not only bests the 18‑135 at all settings, but also the 35 f/1.4. Only the 60 f/2.4 can reach similar resolution at the same f‑numbers. Generally, the 16‑80 is perfectly sharp right from f/4, while the 18‑135 has to be stopped down to f/8 to reach a similar resolution, especially on the image edges. Only at the long end does the 16‑80 benefit from stopping down.

That said, take these resolution measurements with a grain of salt. For instance, a “great” result of 15 (3000 LW/PH) translates to a blur radius of 1.3 pixels, while a “mediocre” result of 10 (2000 LW/PH) is instead 2 pixels. This is scientifically significant, but not at all relevant to (my) photography.

Additionally, the fact that the 60 f/2.4 macro lens scores so highly but the 35 f/1.4 does not is an indication that these measurements might be biased by being taken near the close focusing distance of the lenses. Thus the next set of images compares these lenses at more natural distances.

A grid of crops from a landscape shot, with the two lenses at various focal lenths and f‑numbers
Comparison of lens resolution with natural images. Each image is a 500x500 pixel crop from original photographs. The subject is ca. 100 m from the camera.

At this farther distance, and with a more natural subject, the differences are no longer as easily visible. What differences there are this time favor the 18‑135 instead of the 16‑80. Interestingly, I didn't see any significant differences between these pictures when looking at them “merely” side-by-side in Capture One. Only when I actually assembled these here graphics and looked at them at 200% did the differences become apparant.

Nevertheless, it remains curious that there would be such a difference between the two lenses. Then, someone mentioned that the 16‑80 might suffer from shutter shock, where the camera's mechanical shutter jolts the camera enough to upset the image stabilization system and induce a slight bit of motion blur. An issue such as this might explain the 16‑80's slightly reduced resolution in my test shots. So I created another series of images, but this time both, with the mechanical shutter, and with electronic shutter. In electronic shutter mode, nothing moves in the camera and there can be no shutter shock.

A grid of crops from a landscape shot, with the two lenses at various focal lenths and f‑numbers and with electronic and mechanical shutter
Comparison of lens resolution and shutter shock. Each image is a 500x500 pixel crop from original images. The subject is ca. 100 m from the camera.

From this comparison, I can see no evidence of shutter shock. It might have been an issue on earlier firmware versions of the 16‑80, but my camera (an X-T2) and lens (at firmware 1.05) does not does not exhibit shutter shock. Furthermore, this series of pictures shows the 16‑80 and 18‑135 essentially matched in image resolution.

All of that said, I must add that all of these comparisons used extremely tight crops of high-contrast geometrical features. Most of the differences here are all but invisible in actual photographs. From these resolution experiments, I see no reason to prefer one lens over the other. Both of them are perfectly sharp in everyday use.

Conclusion

So, how to choose between the Fujifilm XF 16‑80 f/4 R OIS WR and the XF 18‑135 f/3.5‑5.6 R LM OIS WR? My 16‑80 has tighter aperture and zoom rings, does not creep, and has a smoother rendering of out-of-focus background. On the other hand, I do find the increased telephoto of the 18‑135 very useful, and it doesn't suffer from wide-angle distortion as much as the 16‑80.

In terms of resolution, I did not find fault with either lens. Both are very sharp across their entire focal range and the entire frame. That said, the 18‑135 does benefit from stopping down for optimum resolution, while the 16‑80 is sharp right from f/4, and the 16‑80 might be sharper for closer subjects.

My tentative conclusion from these experiments is therefore that I would slightly prefer the 16‑80 for people pictures, where the close-focus sharpness and nicer background rendering are advantageous, and the larger aperture at 80 mm might make a difference. And I would prefer the 18-135 for landscapes, where stopping down is usually easy and the longer focal length comes in handy.

That said, the differences in rendering and resolution are really very minor, and the choice most importantly comes down to the focal range. Which is as it should be with modern lenses. And both lenses are of course very well-built, weather sealed, and have fantastic image stabilization. But you probably knew that already.

Footnotes:

1

multiply lenstip numbers by 2×16.7 mm to convert from lpmm (lines per millimeter) to LW/PH (line width per picture height)

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