Fujifilm FUJINON XF 100-400mm F/4.5-5.6 R LM OIS WR

The FUJINON XF 100-400mm F/4.5-5.6 R LM OIS WR is a super-telephoto zoom for Fujifilm X-mount APS-C cameras. It suits birds, wildlife and outdoor sport when you cannot approach the subject. Fujifilm introduced it in 2016. Check whether your outing also needs a wider lens for nearby scenes.

The zoom runs from 100mm to 400mm, so you can frame an animal in its habitat or tighten onto one subject. The trade-off is bulk and light gathering. This is a heavy lens, and its widest aperture narrows to f/5.6 at the long end.

The lens weighs 3 lb 0.5 oz (1375 g) and measures 8.29 in (210.5 mm) long at the wide end. It extends as you zoom towards the telephoto end. Allow space for the hood and caps when packing. A monopod or tripod can take the weight during a long fixed session. Screw-in filters must match the 77mm thread.

The 100–400mm range shapes how you shoot. At 100mm you can place a bird in its surroundings, and at 400mm the same bird fills far more of the frame without moving closer. That reach also serves sport shot from a sideline. A rotary manual zoom ring keeps framing changes under one hand as action develops.

Maximum aperture changes from f/4.5 at 100mm to f/5.6 at 400mm. In woodland shade or at dusk, check whether the required shutter speed calls for a higher ISO. A close subject can stand out against a soft background when there is enough space behind it. The result also depends on focus distance.

Birds in flight reward the zoom range. You can react to a changing distance by zooming rather than swapping lenses, which keeps your eye at the viewfinder between bursts.

Closest focus is 5.7 ft (175 cm), measured from the sensor. Maximum magnification reaches 0.19x at the telephoto end. This can help with approachable birds and larger insects. Check the subject size in the frame before moving closer, and allow room ahead of the lens for light.

Weather sealing makes the lens dust and moisture resistant, a good match for field work in changeable conditions. Fluorine coating helps water and oil slide off the glass, so cleaning after a damp morning is simpler. Both suit a lens that often spends whole days outdoors waiting on distant subjects.

The zoom lock secures the barrel at 100mm for transport. Release it before changing focal length. Image stabilisation helps reduce blur from camera shake when photographing a still subject. It cannot freeze a flying bird or running player, so choose shutter speed for their movement as well as your hold.

The optical formula includes five ED elements and one Super ED element. These glass types help reduce chromatic aberration, where different colours focus at different points and leave coloured fringes along high-contrast edges. A dark bird against bright sky is one relevant example. Their presence does not establish measured image quality.