Fujinon XF100-400mmF4.5-5.6 R LM OIS WR unbiased review

Introduction

The Fujinon XF100-400mmF4.5-5.6 R LM OIS WR is a super telephoto zoom lens for the Fujifilm FX system from the X-PRO1 onwards up to the latest X-Pro2. In 35mm or full-frame format, this would translate to a huge 152 to 609 mm zoom lens, which is some serious reach.

To keep the size and weight down, Fuji has opted for a variable maximum aperture of f/4.5 at the short end to f/5.6 at the far end. Anyone having concerns about shooting a relatively slow tele-zoom handheld should know that it incorporates a 5-stop optical stabilisation system. While other camera manufacturers have opted for a sensor stabilisation system in the last few years, Fujifilm is so confident about their optical stabiliser, that they seem to feel no need to go the same route.

Optical Construction

The quite complex optical construction consists of 21 elements in 14 groups.  This includes five ED lenses and one Super ED lens to help reduce the high degree of chromatic aberration that you’ll often see in telephoto lenses.

It uses a focus-by-wire system with twin linear motors for autofocusing, a system that usually works well for mirrorless camera lenses. Focus-by-wire does have one disadvantage for manual focusing because there is no direct correlation between the focusing ring and the lens elements. The ring drives the focusing motor, instead of overriding it. This never really bothers me, focusing manually feels smooth and comfortable.

Build

Like all Fujinon red label lenses, the XF100-400mm looks and feels like a high-quality optic. Fujinon has also done their best to keep both size and weight down, weighing 3.03 lb (1.375 kg) and measuring 3.73 x 8.29″ (94.8 x 210.5 mm).

This lens does extend about 2,5 inches when zooming, and the lens hood naturally adds to the lenght when installed. The lens hood has a sliding window for easy acces to a polarising or vari ND filter if you’d want to use one. The hood also has a locking mechanism to keep it securely attached to the lens.

It’s water- and dust-resistant, with 13 seals at 12 points, and it should operate in temperatures as low as -10°C. A fluorine coating on the front lens element helps to repel water and dirt.

You’ll find a focus limiting switch on the left side of the barrel that allows you to choose either full range or 5 meters to infinity.  The Program or Aperture Priority switch and the OIS on/off switch are placed above that. Between the zoom ring and the aperture ring is the Lock switch for keeping the lens locked in any range position. The tripod collar is the same design as the one on the 50-140 f/2.8.

Autofocus and Optical Image stabilisation

I tried this lens on the Fuji XE-2 with the latest v4 firmware. The XF 100-400 focusses as well as any XF lens on the XE-2, although you might find that this Tele-zoom is a bit slow in acquiring focus when suddenly bridging large distances (say moving from 100 to 400mm). In this situation, the focus limiter can help.

Focussing in low light can be slow too as this is a rather slow lens, particularly at the long end. If you have any problems here, I would suggest going to higher ISO values. The on-sensor phase and contrast detection points seem to work best in low light when you switch to a higher ISO.

If you want to track fast moving birds and objects, it’s also best to use a monopod and, of course, the wide-tracking AF setting. The 100-400mm is a pleasure to use and thanks to the 5-stop image stabilisation, it’s possible actually to use it handheld. Quite a feat for a telelens at 640mm in Full Frame Equivalence.

Sharpness and Vignetting

Testing sharpness for a tele-zoom that bridges such a distance is not easy. While I would normally test the same view of a test chart at different focal lengths and apertures, this is not possible here in my setup. In real life shooting, however, I did notice some softness at certain focal lengths, and I wondered if this softness had anything to do with the optical image stabilisation or not.

The best way to try this out was some indoor shooting of my 4 300 dpi test charts on a sturdy tripod with image stabilisation turned off, at base ISO and a remote shutter to eliminate shake. Since I’m zooming in on the chart, this is not ideal for comparisons across the focal range, but at least, I have a point of comparison. It’s also important to turn the preset sharpening off for a test like this, although X-TRANS files always need and can tolerate a fair amount of sharpening in my opinion. This is what Fuji does with their in-camera jpeg too.

So what can we learn from these shots?

• Is sharpness more or less uniform across the range at maximum aperture?
• How sharp is this lens across the range?
• Is it useful stopping down to f/8 when possible regarding sharpness and vignetting?

Center Sharpness wide open across the range

The Fujinon XF100-400 looks quite uniformly sharp across the range, with focal lengths between 130mm and 190mm being the sharpest. With zoom lenses covering this range, you’ll often find that shooting at 300mm and cropping to 400mm yields better results, but this is not the case here.