Basti's Scratchpad on the Internet
11 May 2019

Fuji Zoom Lenses

So I bought a new camera. Now I need new lenses. In this post, I am looking for a standard zoom lens, i.e. something that covers a bit of wide-angle, all the way through the normal range, up to a bit of telephoto. In Fuji's lineup these needs are met by

The XC 15‑45 is out, because the zoom ring is not turn-to-zoom like any other zoom lens. I tried it; I couldn't stand it. The XF 16‑55 is out because it is just too expensive and big for me. A bag of primes is not what I want, but I included the XF 27, because that's what I happened to have at hand. All of the above prices are used prices as of early 2019 in Germany.

lenses.jpg
Figure 1: From left to right, the XC 16‑50, XF 27, XF 18‑135, XF 18‑55

Before we get started, all of these lenses are perfectly sharp to my eyes. At least in the center-ish area of the image, every pixel shows different information, which is not something I could have said about some of the Nikon lenses I used to own. Because of that, I will not compare sharpness.

The word of mouth is that the XF 18‑55 is a stellar kit lens, the XC 16‑50 is a bit cheap, and the XF 18‑135 a bit of a compromise. If internet forums are to be believed, these differences are massive, and the XF 18‑55 is really the only acceptable non-prime lens any self-respecting Fuji fanboy can buy. But then again, that's what internet forums would say, right?

With that out of the way, let's have a look at these lenses! I'll use crops from a terribly boring shot linked here for most of my examples. Why this shot? Because a), that's what was available, and b), because it contains areas that nicely showcase these lenses' qualities. All shots were taken at f/8 at 27 mm, ISO 400 and a shutter speed around 1/300 s.

Micro Contrast

I often read that micro contrast really tells lenses apart. To illustrate this point, here's an area with very little overall contrast, particularly between the fence and the orange paint, and the fence and the gray stairs:

microcontrast.jpg
Figure 2: 100% crops, mouse pointers near the critical areas. (Click to view bigger)

If you look very closely, you might find the fence slightly less visible on the XC 16‑50 than on the XF 18‑135 and XF 27, and ever so slightly more visible on the 18‑55. But it should also be obvious that these differences are incredibly tiny, and not worth fussing over.

Corner Sharpness and Chromatic Aberrations

Another common point is corner sharpness, which is typically said to strongly favor primes. This time, the images are cropped from the bottom-right corner of the image that contains some detail, but most importantly a bright white warning sign:

cornersharpness.jpg
Figure 3: 100% crops of the image corner. (Click to view bigger)

And indeed, the XC 16‑50 is noticeably blurry this time, with the other three lenses similarly sharp. The warning sign also highlights color fringes on the transitions from the bright white sign to the dark background. These chromatic aberrations are almost invisible on the XF 18‑55, and mild on the XF 18‑135 and XF 27.

Bear in mind, however, that these are 100% crops in the very furthest corners of a high-contrast image. In normal pictures, none of these issues will be noticeable unless you really zoom in on fine details at the edges of your frame. The chromatic aberrations seen here were already treated in software with the lens correction module in Darktable, but it might be possible to improve on these results with more dedicated processing.

Update: Even more comparison pictures

After publishing the blog post, I still wasn't satisfied: What if the results I got were only true at f/8? What if image quality got worse at a longer focal length? How does my XF 18 stack up?

To answer this, I took another set of pictures and prepared another composite of an crops near the image center, and another one near the lower right corner.

centersharpness_big.jpg
Figure 4: 100% crops of the image center. (Click to view bigger)
cornersharpness_big.jpg
Figure 5: 100% crops of the image corner. (Click to view bigger)

To be perfectly honest, I can not see any significant differences between any of these pictures. At this point, I am starting to question the entire concept of sharpness and micro contrast for evaluating lenses. But at least I learned a lot about how to use the Gimp.

As a sanity check, I repeated the experiment with my old Nikon 18-200, and this was in fact noticeably less sharp. And slightly overexposed. And slightly off-color. That's why I switched to Fuji. But as I said, this was a sanity check, not a fair comparison, as the Nikon D7000 body is much older than my Fuji X-E3, and the lens has surely seen better days as well.

Update: Ergonomics and Balance

The XC 16‑50 and XF 27 operate their aperture with the control wheel on your right thumb. The XC 18, XF 18‑55, and XF 18‑135 have a dedicated aperture ring on the lens instead. Thus, the former two lenses can be controlled with the right hand alone, while the latter two require the left hand on the lens barrel. Zoom is always controlled on the barrel, though.

This preference for one-handed or two-handed operation is supported by the lenses' weight, as well: My camera, the X-E3, weighs about 330 g. With the 200 g XC 16‑50, the weight is mostly in the camera body, and can easily be held and operated with one hand. The 250 g XF 18‑55 and the 500 g XF 18‑135 are more lens-heavy, which makes a two-handed grip necessary, which is a better fit for the aperture ring on the lens.

Personally, I actually prefer the aperture on the thumb wheel over the unmarked aperture rings on the XF 18‑55 and the XF 18‑135. It just feels more natural in my hands. On the other hand, I like the marked aperture ring on the XF 18, particularly for resetting the aperture without looking through the viewfinder, or when the camera is turned off. In fact, I find the ability to operate the camera while turned off to be very useful in general. It is one of the major reasons why I like Fuji cameras.

Close Focus Distance and Magnification

And now, the darling of all photographers: out-of-focus backgrounds. Common wisdom is that the bigger the aperture, the more the background is thrown out of focus. But that's only part of the truth, and honestly, not the most interesting part for these kinds of limited-aperture lenses. Much more powerful is getting closer to your subject: The closer you focus, and the farther away your background, the more the background will be out of focus. This effect gets even stronger when you zoom in.

magnification.jpg
Figure 6: Widest (top) and longest (bottom) shots, each cropped vertically but not horizontally. All shots at f/5.6. (Click to view bigger)

The XC 16‑50 focuses much more closely than any other lens in this list, at 12 and 30 cm (Fuji says 15 cm). You can get really nice background separation with this lens, and great magnification in your macro shots. The XF 18‑55 focuses at 25 and 35 cm (Fuji: 40 cm), which is not particularly impressive. The XF 18‑135 focuses even farther, at 33 and 43 cm (Fuji: 45 cm), but gains magnification through its long tele zoom. The XF 27 is not optimized for this kind of thing at all, at 29 cm (Fuji: 34 cm).

Conclusions

To me, the XC 16‑50 is the winner for a small/light zoom kit. It might be the least great option optically, but the differences are not dramatic at all, and it is the cheapest, smallest, and lightest lens with the most useful wide end and the closest focusing. But it lacks a dedicated aperture ring and is a plastic construction instead of a metal one, which does detract from the haptic joy somewhat.

The XF 18‑55 is optically the strongest lens. It might even beat the XF 27 prime lens on its own turf! But the optical differences to the cheaper XC 16‑50 and the more versatile XF 18‑135 are quite small, and are not be worth the price/weight/inconvenience to me.

The XF 18‑135 is really surprisingly good for what it is. The much longer focal range necessarily comes with compromises in optical quality and bulk, but it seems no significant corners where cut in this case. Considering that this lens usually replaces at least two other lenses, I even find the price reasonable. This is my first choice as a do-everything zoom kit.

The XF 27 is not very strong in any particular way, except size. And that size trumps all. If I just want to throw a camera in my bag without any particular photographic intentions, the XF 27 is my first choice. And possibly the XF 18, if I still have room in my bag.

As some small buying advice, the XC 16‑50 was refreshed in 2015 with the OIS II version, which introduced that nice close focusing distance (highly recommended). The XF 18‑135 was apparently built in two batches, the original made in China version that seemed to have horrible QA issues, and a second made in Philippines version in 2017 without.

What I didn't mention

Aperture. The XF 18‑55 and XF 27 have a wider maximum aperture than the XC 16‑50 or XF 18‑135, by about two thirds of a stop. Shooting at bigger apertures makes brighter pictures with stronger background blur, and some loss in sharpness. I don't find the optical performance wide-open particularly interesting, because most of the time I'd use large apertures to blur the background, making sharpness and distortion mostly irrelevant. And as I said above, getting closer is usually more effective for background blur than maximum aperture, anyway.

Image stabilization. The three zooms offer optical image stabilization systems. From what I can tell, the XF 18‑135 is significantly more effective in this regard than the XC 16‑50 or the XF 18‑55. Hand-held shots with up to about 1/10th of a second seem easily achievable with the XF 18‑135, whereas the unstabilized XF 27 becomes blurry at 1/40th. Videos are noticeably smoother with the XF 18‑135 as well.

Weather sealing. The XF 18‑135 is weather sealed, the other lenses are not. My camera is not, so I don't care.

Distortion and Vignetting. Is fixed in post. No need obsessing over it.

Autofocus speed. Is good. No need obsessing over it.

Tags: photography
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