Lens Test: EF-S 18-55mm f/3.5-5.6 IS STM

Arguably the biggest single update to the EOS 700D is its new basic kit zoom - the EF-S 18-55mm f/3.5-5.6 IS STM. The most important change is its silent STM focus motor and revised optics to accommodate an internal focus design. However in terms of image quality it's very much the same as its predecessor, the EF-S 18-55mm f/3.5-5.6 IS II: click here to compare the two in our lens data widget. This means it's pretty competent, as kit lenses go, but can't match more expensive zooms or even the cheapest prime for outright sharpness.

Note: the data displayed in our widget below uses the EOS 7D as the test body, for consistency and easy comparison with the rest of our Canon lens data. Because the EOS 700D and EOS 7D use similar 18MP APS-C sensors, we expect these results to be representative for the EOS 700D too.

Sharpness Sharpness results are perfectly reasonable for a kit zoom, and very consistent through the zoom range. As we'd expect the corners tend to look a little soft when the lens is shot wide open, but improve on stopping down. In general the lens performs best around F5.6-F8.
Chromatic Aberration Chromatic aberration is visible but not extreme, and as usual it's worst at wideangle. Note that modern Canon SLRs, including the 700D, can correct this automatically in their JPEG processing anyway.
Vignetting There's a moderate amount of vignetting (1.4 stops) at 18mm F3.5, but it effectively disappears on stopping down to F5.6. At longer focal lengths it's not really ever a problem at all. Most recent Canon SLRs will correct this in JPEG processing by default.
Distortion There's pretty strong barrel distortion at wideangle (2.8%), which gradually reduces as you zoom in. It's still visible, but less pronounced, at 24mm; from 35mm to 55mm, distortion is minimal.

Macro Focus

Macro - approx 58 x 39mm coverage
Measured magnification: 0.38x
Distortion: negligible

Minimum focus distance*: 24cm
Working distance**: 11 cm
Focal length: 55mm (88mm equiv)
* Minimum focus is defined as the distance from the camera's sensor to the subject - the position of the Nikon's sensor is not marked, so this figure is approximate.
** Working distance is measured from the front of the lens to the subject

The 18-55mm STM can focus impressively close, down to just 11cm from the front of the lens (in manual focus anyway - the camera won't autofocus quite so close). Image quality is pretty typical for a kit zoom - it's not great wide open, but perfectly OK when stopped down.

The whole frame is very soft at F5.6, and while the centre of our chart test shot sharpens up well at F8, the corners are very soft. But they improve on stopping down, with best results at F16. More positively there's only a tiny bit of colour fringing in the corners due to chromatic aberration, and barely any distortion.

Image Stabilization

The EF-S 18-55mm f/3.5-5.6 IS STM includes Canon's familiar optical image stabilisation system. The mechanism is effectively silent when operational, with only the stabilization of the viewfinder image confirming that it's running. Canon claims the IS system allows shutter speeds four stops slower than usual to be used for hand-held shooting.

To determine the effectiveness of the IS system we subjected the 18-55mm STM to our studio image stabilization test, using both the wideangle and telephoto settings. The subject distance for these tests was approximately 3m, and the test camera was the Canon EOS 700D.

We take 10 shots at each shutter speed and visually rate them for sharpness. Shots considered 'sharp' have no visible blur at the pixel level, and are therefore suitable for viewing or printing at the largest sizes, whereas files with 'mild blur' are only slightly soft, and perfectly usable for all but the most critical applications.

18mm IS OFF 55mm IS OFF
18mm IS ON 55mm IS ON

These tests show that Canon's IS system works well, as we've come to expect. Under these pretty optimal conditions we see at least three stops stabilisation, and if you take enough shots you've got a fighting chance of getting sharp images at shutter speeds as low as 1/2 sec at 18mm, or 1/8 sec at 55mm.

Needless to say you do have to pay attention to your hand-holding technique, and be prepared to wait a second for the IS system to settle down after you half-press the shutter. You may not get quite such good results outside in the cold after a few coffees either. But overall this is as good as you'll see from a kit zoom.

Silent focusing during movie recording

The 18-55mm's STM focus motor brings a new trick - silent refocusing during movie recording. On the EOS 700D, you can refocus during movie recording to a new subject simply by touching the screen. Here we show an example of how this works.

1920x1080 25fps, MOV, 24 sec, 108 MB Click here to download original file

This movie was shot in a quiet room, using the camera's built-in stereo microphones and auto record level control. Focus is initially on the foreground, then moved to the middleground, background, and back to foreground using touchscreen focusing. It works pretty well in practice, although the operation of the AF system is quite visible in the original Full HD movie, with noticeable 'shimmering' as the contrast detect AF system determines correct focus each time. But focusing is essentially silent.

For owners of older cameras considering the 18-55mm STM for its silent focusing, we'd suggest testing before you buy. User reports suggest that the STM lenses work best on Canon's most recent bodies from the EOS 650D / T4i onwards, and video focusing may well be noisier and less smooth on older models. Caveat emptor.

'Focus-by-wire' electronic manual focus

Another feature that's a consequence of the lens's STM focusing motor is electronic manual focus. The manual focus ring isn't mechanically coupled to the focus group, but instead drives the lens's focus motor. Not so long ago, this kind of 'focus-by-wire' system was seen as a distinct disadvantage. But things have changed, and on the 18-55mm STM it's actually a huge improvement over the previous lens's loose, imprecise manual focusing. Instead you now get a 'proper' focus ring that rotates very smoothly, and gives precise control over manual focusing. The internal focus design also means that filters don't rotate during focusing, and allows the use of a more effective petal-type lens-hood.

The 18-55mm STM gains a proper manual focus ring with a ridged plastic grip. On the previous model the focus ring was moulded onto the extending section of the lens barrel, and moved forwards during focusing.

The lens test data in this review is produced in collaboration with DxOMark. Click here for DxOMark's full test data of the EF-S 18-55mm f/3.5-5.6 IS STM, over on dxomark.com