As I have already pointed out earlier, unlike its modern counterparts, the lens is not weather-sealed. This means you have to be extra careful when using the lens in extreme conditions, especially when it is very humid. When shooting in very rainy conditions in New Zealand, the front element of my lens fogged up a little. I put it away and let it dry up, and the moisture disappeared. So keep this in mind when shooting in the field – you might end up permanently damaging the lens. What little pincushion distortion there is can be corrected for more critical use by plugging these figures into Photoshop's For my lens tests on other systems I normally shoot in RAW and process the files with corrections disabled to see what’s happening behind the scenes. But the more I shoot with the Fuji X system, the more I appreciate the out-of-camera JPEG performance, especially when using Lens Modulation Optimisation (LMO) with Fujinon lenses. I’ve also found few RAW converters which can do justice to the X-Trans sensor. So in line with my other XF lens tests, I’m going to present crops from unaltered out-of-camera JPEGs here (with LMO enabled as default) as I believe they show the lens in the best light. I did of course also shoot the scene in RAW and if I find a workflow which delivers good results in the future I’ll update this review with RAW comparisons as well.

Manual focusing is entirely electronic; the manual focus ring isn't connected to anything other than a digital encoder. There is spherochromatism, which can cause color fringes on things that aren't in perfect focus. Spherochromatism is a completely different aberration in a different dimension than lateral color fringes. As you can see in the product pictures, it complements the latest Fujifilm X-T4 flagship camera very well. It doesn't feel at all front-heavy and more than matches the body in terms of its build quality. The only gotcha with this Fuji lens is that there is no instant manual-focus override. You have to move a switch on your camera to get to or from manual focus mode. One area where I have found the lens, or should I say my copy, to struggle is with flare. As I shoot a lot at sunrise and sunset, often shooting directly into the sun, my lens sometimes suffers flare, improvements in this area would have been appreciated.

Fujinon XF 10-24mm F4 R OIS WR: Specification

The lens mount does not feature a rubber gasket. There is a rear lens element that stays in place, which does a nice job of keeping dust from entering the lens when it is dismounted. The front lens element is bulbous but reasonably small relative to the lens. The zoom ring is broad and rubber-coated with ridged texture for ease of use and comfort. It glides well and has a really small travel distance from 10mm to 24mm. The 23mm f/1.4 R, however, has the ability to shoot in lower light with a more shallow depth of field as it is 3 stops faster than the XF 10-24mm f/4 R OIS WR.

There's not a ton of choice for shooting wide-angle in the Fuji system - either this lens, or either of the 14mm or 18mm primes. That said, the 10-24mm ƒ/4 R OIS is a very capable performer, offering sharp results at every focal length with the possible exception of 24mm, plus the added versatility of a zoom design and OIS. If you want to shoot ultra-wide on a Fuji X-mount camera, there's no alternative at this time that offers the same features. The Fuji XF 10-24mm f/4 OIS ASPH is optically close to perfect, and is also very well built, making it the world's best APS-C ultrawide zoom even if it didn't have OIS.

Autofocus Performance

When Fuji first announced its X system, the widest lens in the line-up was the compact XF 18mm f/2 R. Although the company followed up with the wider XF 14mm f/2.8 R later that year, many photographers including myself, were really hoping to see an ultra-wide angle zoom that would cover the 14-24mm full-frame equivalent range. So when the XF 10-24mm f/4 R OIS was finally released a year later, I bought a copy for myself right after acquiring the Fuji X-T1. I did it without hesitation because I found the lens to be exactly what I needed – it coupled extremely well with my X-T1, and unlike my Nikon 14-24mm f/2.8G, it could take filters. So it became a part of my “go-to” kit for travel photography needs. X-T2 + XF10-24mmF4 R OIS @ 15.9mm, ISO 200, 1/2, f/11.0 There are no better lenses to use on the Fuji system at any price. Forget slumming with LEICA or other off-brand lenses; you can't get anything sharper and any other lens won't autofocus or autoexpose or log data or be optimized by the camera's DSP, and no other lens will have a diaphragm that opens and closes automatically as needed for focus and shooting. Despite the addition of this weather-sealing, the XF 10-24mm F4 R OIS WR still manages to weigh 25g less than its predecessor. I found in practical use the zoom ring was quite stiff – probably to prevent unwanted movements in focus distance.