Studio Tests

NOTE the line marked 'Nyquist Frequency' indicates the maximum theoretical resolution of the camera body used for testing. Whenever the measured numbers exceed this value, this simply indicates that the lens out-resolves the sensor at this point - the calculated MTF values themselves become meaningless.

The image-stabilised 18-55mm gives a good account of itself in our tests, and is clearly much improved over the old kit lens which we've grown to know and not quite love over the last few years. It distinctly outperforms the more expensive 17-85mm at wide angle, and matches it over most of the rest of its range; however this is tempered by a slightly disappointing performance at telephoto.

Macro Focus

A quite impressive performance here, especially for an inexpensive lens. Our measured magnification is 0.36x, slightly better than Canon's specificed 0.34x, and this is is achieved at a focus distance of 25cm, giving a working distance of about 11 cm between the front lens element and subject. Image quality is generally good too; as is often the case results are soft wide open (due to blurring from spherical aberration), but the centre sharpens up nicely at F8, with the corners not far behind. There's practically no visible distortion and just a hint of blue/yellow chromatic aberration. Overall a very good showing.

Macro - 62 x 41 mm coverage Distortion: very mild pincushion Corner softness: Minimal Focal length: 55mm (88 mm equiv)

Specific image quality issues

Flare

Like most kit zooms, the 18-55 IS is rather prone to flare in bright light, something which is not really helped by the pretty ineffective hood. The samples below exhibit fairly severe flare effects, most visible on the right side of the frame, in both cases due to strong off-axis light sources. The problem lies at least in part with the cheap construction of the lens, which simply makes it less effective at suppressing internal reflection of stray light. This also results in lower overall image contrast when compared to more expensive lenses such as the 17-85mm IS USM.

18mm F16	30mm. F8.0

Optical Image Stabilisation

Canon claim that the new image stabilisation unit developed for this lens (along with its sister 55-250mm telezoom) is at least as effective as the more complex unit on higher end lenses such as the 17-85mm IS USM, allowing hand-holding at shutter speeds four stops slower than usual without seeing blur from camera shake. The stabiliser is almost completely silent and free of vibration in operation, and aside from the stabilising effect on the viewfinder image, you’ll hardly notice it operating at all.

We tested the IS system at both the long and short ends of the zoom range in our standard studio test. With its effective focal length range of 29-88mm, we'd normally expect to be able to get good results handheld at 1/30 sec at wideangle, and 1/90 sec at telephoto without image stabilisation. The subject distance for these tests was approximately 2.5m.

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

The results here a generally similar to those we obtained with the 17-85mm IS, confirming the effectiveness of Canon's new simplified image stabilization unit. At 18mm and a shutter speed of 1/6 sec, IS is delivering 50% critically sharp shots, compared to just 10% without. Even at the very slow shutter speed of 0.3 sec, IS is giving usable images with no more than mild blur 70% of the time; we obtained none whatsoever with it switched off.

Performance is just as good at the telephoto end; at 1/25 sec, IS gives 80% sharp images in contrast to 20% sharp without IS; and at 1/6 sec, 80% of images are usable with IS turned on, in comparison to none at all with it turned off. Overall the optical image stabilization genuinely does confer a very useful advantage when handholding the camera.