Verdict

Canon EF 16-35mm f/4L IS USM review – Introduction

You could forgive most photographers for thinking that a 16-35mm lens would be intended for less-than-full-frame cameras. After all, a focal range such as this would provide a sensible, if slightly odd, 25-56mm on an EOS EF-S APS-C body. The lens on test here, though, is not designed for APS-C bodies, but is what Canon calls an ultra-wide zoom for full-frame cameras. ‘Ultra’ is something of an overused word. I think it is more accurate to say this is an ‘extremely wideangled’ lens. With lenses such as these, we have come to expect a fisheye design, with associated heavily barrelled images, but in this case, Canon assures us that it has provided rectilinear drawing across the frame – so buildings will appear as rectangles, rather than bulging in the middle.

Canon EF 16-35mm f/4L IS USM review – Features

This isn’t the first Canon EF full-frame lens to provide viewing angles of 108°-63°, as the EF 16-35mm f/2.8 L II USM has been around for several years. The new lens is, however, the first to feature Canon’s IS system. Image stabilisation is considered to be less of a priority for wideangles than telephoto lenses, but camera shake is only less noticeable in a wideangle – not non-existent, as the same laws of physics and focal length remain. Canon claims this version of IS gives us the ability to handhold a lens while using a shutter speed 4 stops longer than we should expect. In theory, it should be possible to obtain sharp images with this model at speeds as long as 1sec without the use of a tripod. More realistically, if we assume that the ‘safe’ shutter speed is 1/60sec, this lens’s 4-stop advantage would allow us to shoot handheld at 1⁄2sec.

This model includes Canon’s Ultra Sonic Motor (USM), with the aim of providing near-silent and extremely fast autofocus. This should be of great benefit when shooting moving subjects as they approach the camera, as relative distance changes are dramatic and harder to track.

The lens is constructed of 16 elements in 12 groups, with UD (ultra-low dispersion) glasses used in two elements to tackle chromatic fringing and the blur that occurs when wavelengths focus at different depths. Elements are treated on both faces with Super Spectra coating to reduce internal reflections – a particular problem in wideangles – and Canon has used fluorine coating on the exterior faces of the front and rear elements to discourage water and dust.

Canon is proud of its nine-bladed aperture, which, it claims, produces the roundness of iris required for attractive out-of-focus highlights, or bokeh. However, one wonders just how much of a scene it will be possible to render out of focus with an f/4 lens of such focal lengths as these.

Canon EF 16-35mm f/4L IS USM review – Build and handling

Being an L professional lens, this 16-35mm f/4 is designed to withstand the rigours of constant use in all conditions. Remarkably light and narrow, the exterior gives the appearance of being coated with protective rubber, and Canon claims it is sealed against moisture and dust at all seams and joins. The zoom control ring is the closer of the two ribbed rings, separated by a distance scale beneath a window. The zoom ring requires only a one-fifth rotation to adjust from one extreme of the focal range to the other, while only 45° takes the focusing ring from infinity to the closest focusing distance of 28cm.

I used the lens with the EOS-1D X for this test, and the two worked nicely together, with the lens adding hardly any noticeable mass to the combination. If the AF performance of the camera was hindered by the use of this lens I didn’t notice, as focus seemed to zip as quickly as always from one extreme to another.

Image: These images show the extent of the zoom range, with the longer end displaying a little pincushion distortion

Canon EF 16-35mm f/4L IS USM review – Image quality

Image: While the vignetting of the 35mm end of the zoom might be moderate, a polariser filter had added to the effect here

When optics go to extremes, we are usually treated to an array of aberrations to inspect, and with wideangles such as this we should be on the lookout for the bending of straight lines, dark corners and the separation of colours, and a loss of sharpness at the frame edges.

Vignetting is a feature of images taken with this lens, no matter what the focal length or aperture. Wide apertures combined with the wider focal lengths produce the more dramatic effects, but even with the aperture closed to f/16 at the 35mm setting you can expect the corners of the frame to be about 0.2EV darker than the middle. Fortunately, in most scenes, darkening of up to 0.3EV will not be obvious, but in critical applications it will be noticeable, but also easily correctable for the small price of a bit of amplified noise in the corners.

The difference in edge and corner resolution is a characteristic that is more difficult to remedy, and in flat subjects the coma aberration is more noticeable. The onset of the loss of sharpness is quite sudden, though, and plays more of a part right in the corners of the frame at the widest focal lengths than it does along the diagonal path from the centre of the frame. As such, it affects a relatively small area of the frame.

Sharpness in the centre of the frame is excellent at all apertures and focal lengths, and it took some searching to find the chromatic fringing I had expected to see in the extremities of the frame.

Resolution

There is always some distance between edge and corner sharpness in this lens; the wider the focal
length and aperture, the greater that distance will be. Edge sharpness remains mostly constant, but the centre is best at f/8 and 16mm.

Shading

Corners darken by a noticeable 0.4EV at the widest setting of the lens, when used at f/4. Things improve with smaller apertures and longer focal lengths, but only to 0.2EV.

Curvilinear distortion

Good drawing is hard enough in a fixed wideangle lens, but in a zoom the problem is multiplied. Quite heavy barrelling turns to pincushion at about 24mm, which provides a relatively undistorted haven.

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Canon EF 16-35mm f/4L IS USM review – Our verdict

This is a very good lens. It has a useful IS system that allows handholding for long exposures, and less vignetting and quality fall-off at the edges than expected. If the ability to handhold your camera is more important than achieving a shallow depth of field, this model might be a better option than Canon’s f/2.8 version – which retails for almost the same price. This really isn’t a cheap lens, but a 16-35mm range like this is hard to come by, and for the architectural or landscape photographer, it provides a very useful focal range, and is less expensive, less bulky and lighter than owning the six separate fixed lenses that it encompasses.

Wideangle zooms can be disappointing, but I’d be happy to use this model knowing that the aberrations it displays are moderate, non-destructive and easy to work with.

Image: I was quite amazed at the length of exposure I could manage handheld (shot at 1/4sec shutter speed)

Score: 4 out of 5

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