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We Review the Sigma 100-400mm f/5-6.3 DG DN OS Contemporary Lens for X Mount

There is a lot to love about Sigma’s new 100-400mm f/5-6.3 DG DN Contemporary lens for Fujifilm X mount cameras, including superb image quality, a compact design, and image stabilization – all at an affordable price.

The Sigma 100-400mm f/5-6.3 DG DN OS is not a brand new design, but rather an existing lens that Sigma has now made available for the Fujifilm X Mount camera system. This is the second zoom lens Sigma has offered for the X Mount, joining the 18-50mm f/2.8 DC DN, also an impressive lens, which I reviewed a few months ago. Both lenses are part of Sigma's Contemporary line, which are designed to be compact and affordable while offering high image quality.

Sigma 100-400mm f/5-6.3 DG DN lens for X mount


Focal length: 100 to 400mm

Maximum aperture: f/5 to f/6.3

Filter size: 67mm

Minimum focus distance: 3.61 feet / 1.1 m

Maximum magnification: 0.24x

Optical design: 22 elements in 16 groups

Diaphragm blades: 9 rounded

Dimensions (ø x L): 3.39 x 7.76" / 86 x 197.2 mm

Length at maximum extension 10.92" / 277.3 mm

Weight: 2.5 lb / 1,135 g

The first thing you will notice about the 100-400mm, and perhaps the best part about the lens, is its compact size and weight. Considering the focal length, which is a 150-600mm full frame equivalent, and that it has a built-in image stabilizer, the lens is quite compact and small and light enough to handhold for extended periods of time without feeling fatigued. Having used other lenses in this zoom range, which are considerably larger and heavier, I appreciated the smaller size right away.

The 100-400mm has a four-stop image stabilizer with two modes, one for general shooting and one for panning. The zoom and manual focus rings are both large and easy to find when the camera is at eye level, and both rings move smoothly with just enough resistance. The zoom is external, so the barrel will extend when zooming out towards the 400mm range. The 100-400mm has an internal focusing system, a stepping motor which Sigma says is “optimized to the latest algorithm,” an AF Function button which activates the autofocus, AF-L/AF switch, focus limiter switch, and an image stabilization switch which lets the user choose between the standard setting or panning mode. It also has a zoom lock and a dust- and splash-resistant seal around its metal mount. One great feature is the ability to use either the zoom ring or simply pull/push the lens to zoom in or out. I found this to be very useful when shooting fast moving subjects and much quicker to use than the zoom ring. As someone who tests a lot of lenses and uses multiple camera systems, all of which rotate in one direction or the other, this thoughtful feature definitely helped. The lens comes with a rubberized lens hood and front and rear lens caps, but unfortunately, a tripod collar is not included. The tripod collar is available to purchase separately, and a rubber ring at the back of the barrel can be removed to accommodate the collar. Although the lens is light, as I mentioned, the tripod collar is still a necessity for a lens of this length and size, so be prepared to purchase one at some point.  Although the lens is compact and light and part of Sigma's budget friendly line, it feels very solid and well-constructed.

Fujifilm X-T5 and Sigma 100-400mm. ISO 2,000 1/1,250 sec, f/6.3

Fujifilm X-T5 and Sigma 100-400mm. ISO 800 1/1,600 sec, f/5.6

I tested the 100-400mm with both the X-T4 and X-T5 to see what the practical differences would be in the autofocus speed, accuracy, and response time. For those of us using one of Fujifilm’s latest generation cameras like the X-T5, the autofocus performance is fast and accurate. I was very pleased with the results when shooting a college soccer match, as the lens had no issue tracking moving subjects and creating sequences shot at 15 frames per second that were all in sharp focus. The lens was also able to track a moving player without losing their face as other players moved in and out of the frame. After shooting about 1,000 images, I had only a handful that were not in focus. I used the camera on continuous autofocus with face/eye tracking enabled, and with AF-C option 5 for erratically moving subjects. When shooting birds, I was again pleased with the results, and pleasantly surprised by how the lens was able to pick out a bird obscured by tree branches. There were a few times, however, where the lens would not want to grab focus on a bird sitting in a tree, or when it would pulse ahead or behind the subject, which was odd, considering it had no trouble locking on a moving soccer player. Additionally, the autofocus system is completely silent, and in general, the tracking worked well for birds, sports, and kids photos.

On the X-T4, which has Fujifilm’s older autofocus system, there was a noticeable difference in the speed and stickiness of the autofocus. I used the X-T4 at the same soccer match, and although I was able to capture some great images in sharp focus, it was more challenging to do. On the X-T4, the focusing lacked the stickiness when tracking subjects, resulting in a larger rate of missed images. I decided to test the lens on the X-T4 as well as on the X-T5 since many Fujifilm users considering the 100-400mm will be using a camera with the older-generation autofocus system, but, of course, this critique is more on the camera than on the lens itself. 

Fujifilm X-T5 and Sigma 100-400mm. ISO 3,200 1/2,000s  f/6.3. The lens did an excellent job tracking birds even when obscured by branches.

Fujifilm X-T5 and Sigma 100-400mm. ISO 2,500 1/640 s, f/6.3

Image Quality

The 100-400mm creates sharp, contrasty, images, with excellent color rendition. At all focal lengths, the results were very good. Although the f/5 maximum aperture is not fast, I was able to create nice separation with pleasing bokeh, as in this image of my son taken at 165mm and f/5.6. I did notice some purple fringing when shooting under a bright midday sun, but it was not an issue when shooting in less harsh lighting conditions. In my testing, I also found that the colors produced by the 100-400mm were a bit cooler than what I typically get from my Fujifilm lenses when shooting in Fuji's Provia standard film simulation. 

Part of the reason the images are so sharp at all focal lengths is because of the image stabilization system, which works extremely well. I used both the standard setting 1, and then setting 2 designed for panning, and in both cases, the stabilizer helped to combat any shaking as I handheld the lens. 

Fujifilm X-T5 and Sigma 100-400mm. ISO 1,250, 1/1,600 s, f/5.6.

Fujifilm X-T5 and Sigma 100-400mm. ISO 800, 1/400 s, f/6.3

What I Like

  • Compact size and weight
  • Excellent layout and handling
  • Fast autofocus
  • Nice build quality
  • Image stabilization

What I Didn’t Like

  • Tripod collar sold separately


The Sigma 100-400mm f/5-6.3 DG DN OS is excellent in just about every way and certain to be a popular choice for Fujifilm shooters. Having tested a number of lenses in this focal range, the compact size and weight combined with the excellent handling and layout, features, and image quality, give this lens an edge over much of the competition. Aside from the fact that the 100-400mm does not include a tripod collar, I found little to quibble about with this lens and enjoyed the shooting experience and results very much.

You can purchase a Sigma 100-400 f/5-6.3 DG DN OS Contemporary lens here.

Pete Coco's picture

Pete Coco is a portrait photographer and musician based in New York. When not performing as a jazz bassist, Pete can be found in his studio working with a wide range of clients, although is passion is creating unique portraits of other musicians and artists.

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Nice review and I'd recommend anyone checks out the video version.

You reference other unspecified much bigger/expensive FF lenses, but what is really missing that's relevant to all Fuji shooters is a comparison to what's also available for Fuji:

- XF 100-400
- XF 150-600
- Tamron 150-500

Even if you haven't used the other lenses, acknowledging their existence as alternatives and comparative strengths and weaknesses would be very useful, as their are options out there.

The lens most will be comparing to is of course the heavier 100-400 which can be bought used for a decent amount less than the Sigma these days.

It's nice to see a review of a lens that isn't just weighing it up against the competition, but focussing on the lens in front of you. But some comparison is needed.

Thanks for the comment. The particular lens I was referencing was the Tamron 150-500. I appreciate the feedback for further vids and reviews.