Canon EF-S 15-85mm f/3.5-5.6 IS USM

Lens oracle, Gary Wolstenholme examines the new 15-85mm IS USM lens from Canon.

Canons' 15-85mm lens costs around £639 and is the natural replacement for their popular EF-S 17-85mm IS USM lens which can be had for around £380, due in part to this new lens becoming available. The extra 2mm at the wide end gives a useful wide-angle field of view, equivalent to 24mm on a full frame camera. Other improvements have been made to the exterior design of the lens and to the image stabiliser, which now promises to allow for shots to be taken at shutter speeds up to four stops slower.

This lens fill a niche that not many third party manufacturers compete in, with most tending to offer larger zoom ranges at this price point. Sigma do offer two 17-70mm f/2.8-4 lenses though. Besides having a shorter zoom range, the cheaper of the two has no image stabiliser, standard micro motor focusing, but does have a brighter maximum aperture and costs only £250. A new updated version costs around £330 and provides optical stabilisation and a silent focus motor for the extra money.

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Handling and features
Overall, this lens feels quite solidly built, with much of the exterior being taken up by the wide rubberised zoom ring. Most of the lens barrel is constructed from high-quality plastics, which have a pleasant textured finish to them. The zoom action is very smooth, well damped and there is enough resistance to prevent zoom creep when the camera is pointed downwards.

The lens accepts 72mm filters and users of polarising filters will be glad to know that the front filter ring does not rotate during zooming of focus due to the internal focus design. As this is an EF-S lens, a black plastic baffle sticks out a little further than the rear of the lens mount. Photographers still using Canon's older bodies, such as the EOS 10D, will be unable to mount this lens on their camera.

The improvements Canon have made to the design are welcome as they do improve the handling and general quality feel of the lens during use when compared to the older 17-85mm.

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Performance
For this review, the lens was tested on a 15.1Mp Canon EOS 500D using Imatest.

At 15mm and f/3.5, the resolution of this lens is acceptable enough to please many. However close the aperture down just one third of a stop and the resolution increases to excellent levels in the centre and is still very good towards the edges of the frame. Diffraction starts to reduce sharpness from about f/8 onwards.

Just as with most zoom lenses, the resolution is affected by zooming in. By 35mm the resolution is still good from wide open at f/4.5 through to f/11. Surprisingly, the lens actually performs better at 85mm, producing very good resolution in the centre wide open and at f/8.

Resolution at 15mm

Resolution at 35mm

Resolution at 85mm

Chromatic aberrations aren't too much of an issues with this lens. At their worst, colour fringes just exceed three quarters of a pixel-width at 15mm and f/3.5, which shouldn't cause too many problems in normal shooting scenarios.

Chromatic Aberrations at 15mm

Chromatic Aberrations at 35mm

Chromatic Aberrations at 85mm

At 15mm and f/3.5 the corners of the image are a whopping 4.4stops darker than the image centre, which is a very high level of vignetting and will be very noticeable. At this focal length stopping down to f/8 is necessary for even illumination. The lens performs better at 85mm, as the corners are only 2.2stops darker than the image centre at f/5.6.

Distortion is often an issue with larger zoom ranges, and this lens is no exception. At 15mm Imatest recorded 5.68% barrel distortion, which will very noticeable when straight lines are of importance. However the distortion pattern is uniform so should be easy to correct in image editing software. Things are much better at 85mm, with a barely noticeable 0.37% pincushion distortion recorded.

Chromatic aberration is minimal even in high contrast images.	Barrel distortion is evident at 15mm but is constant so can be corrected.

Although Canon's Super Spectra Coatings have been applied to this lens, it can be quite prone to flare, ghosting and loss of contrast in severe contra-light situations. With strong light sources in the frame, a veritable rainbow of coloured ghosts are present across the image. Similar light sources outside the frame will cause similar patterns, and loss of contrast. Canon do not supply a lens hood as standard, so it may be worth factoring in the cost of the EW-78E petal-shaped hood, which costs around £37, bringing the total price for the lens plus hood to just over £670.

The improved Image Stabiliser fitted to this model appears to work well in practice. I find I am able to regularly get sharp shots at 1/8sec at 85mm and with shutter speeds as low as half a second at 15mm, which is very impressive performance.

DxOMark provides objective, independent, RAW-based image quality performance data for lenses and digital cameras to help you select the best equipment to meet your photographic needs. Visit the DxOMark website for tests performed on the Canon EF-S 15-85mm f/3.5-5.6 IS USM.

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Verdict
During testing, this lens has proved itself a capable successor to the popular EF-S 17-85mm IS USM. Although it has some flaws, it is capable of producing excellent results, so long as the limitations of the lens are taken into account.

The lens handles well, is very sharp at most aperture and focal lengths, and the Image Stabiliser performs excellently.

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Pros

Useful zoom range

Excellent sharpness at most apertures and focal lengths

Image Stabiliser

Good build quality

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Cons

Distortion

Vignetting at 15mm

Flare and ghosting performance (no lens hood supplied)

FEATURES
HANDLING
PERFORMANCE
VALUE
OVERALL

Canon EF-S 15-85mm f/3.5-5.6 IS USM: Specification

Price	£639
Contact	www.canon.co.uk
Filter size	72mm
Format	APS-C
Construction	17 elements in 12 groups
Angle of view	84° 30' - 18° 25'
35mm equivalent focal length (on APS-C body)	24 - 136mm
Internal focusing	Yes
Image stabilisation	Yes
Minimum focus	35cm
Maximum aperture	f/3.5 - 5.6
Minimum aperture	f/22 - 38
Weight	575g
Size	87.5x81.6mm
In the box	Lens caps

The Canon EF-S 15-85mm f/3.5-5.6 IS USM costs £639 and is available from Park Cameras here:

Canon EF-S 15-85mm f/3.5-5.6 IS USM

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