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To compare real-life sharpness when zoomed-out, we shot this scene with the Canon EF-S 15-85mm IS, EF-S 17-85mm IS and EF-S 18-135mm IS, using an EOS 7D body at all apertures. The 7D was set to RAW to avoid in-camera JPEG corrections; all files were processed in Canon DPP with lens corrections disabled and the default sharpness of 3. IS was disabled on each lens, and magnified assistance in Live View used to confirm the focusing.

The first table compares crops taken from the corner of each image at different aperture settings and the second table compares crops taken from the centres of the same images. Below these you'll find two further tables which switch the results from the EF-S 17-85mm IS USM for those from the EF-S 18-55mm IS kit lens for those thinking of upgrading.

While we matched the coverage as closely as possible for our tests at 50 and 85mm, we decided to test each lens on this page when fully zoomed-out. As such, each captured a slightly different field-of-view at their widest focal lengths of 15, 17 and 18mm. This poses an issue when it comes to choosing an area to crop from the corner, as subjects close to the edges of the 18mm sample will be comfortably further-in on the wider lenses, giving them an unfair advantage. As such we have taken our corner crops below from an area pressed up against the far right edge of each frame, and very close to the bottom.

The areas may not show the same subject area as a consequence, but they do allow us to compare overall sharpness and correction from the same portion of the frame. Below this table you'll see crops taken from close to the centre of each image and again the variations in focal length have resulted in slightly different areas being captured.

The unique selling point of the EF-S 15-85mm IS USM is its wide angle coverage and the lens certainly doesn't disappoint when fully zoomed-out. Even with lens corrections disabled there's minimal coloured fringing to worry about and most impressively of all, details remain respectably sharp right up to the corners, even with large apertures. The latter is very important as while fringing, vignetting and geometric distortion can all be corrected fairly effectively in software, there's little you can do about a frame which becomes softer towards the edges.

At f3.5, the EF-S 15-85mm IS USM delivers a noticeably sharper result in the corners than the EF-S 18-135mm IS, and again avoids the obvious fringing on the cheaper model. At f4, both lenses have become fractionally sharper, although the EF-S 15-85mm IS USM remains comfortably superior in the corners. At f4 we can also now compare the EF-S 15-85mm IS USM against its predecessor the EF-S 17-85mm IS USM. Unlike its successor, the EF-S 17-85mm IS USM suffers when fully zoomed-out with noticeable softening in the corners and significantly worse coloured fringing. So of the three lenses here, the EF-S 15-85mm IS USM is taking a comfortable lead.

At f5.6 all three lenses have lost most of the darkening effect due to vignetting and both the EF-S 15-85mm IS USM and the EF-S 18-135mm IS enjoy sharper details, although the latter still suffers from obvious coloured fringing. Sadly despite a reduction in vignetting, the EF-S 17-85mm IS USM f5.6 corner sample hasn't become significantly improved in other respects.

The story continues at f8 with gradually sharper results from the EF-S 15-85mm IS USM and EF-S 18-135mm IS, albeit again with more obvious coloured fringing on the latter, while the EF-S 17-85mm IS USM remains relatively soft in the corners.

When viewing the entire frames, this story becomes more obvious with the EF-S 15-85mm IS USM taking a comfortable lead in corner performance over the other two models when all three are zoomed-out. It's a great start for the new lens, but be sure to check our results at other focal lengths as it's not necessarily a slam-dunk across the entire range. Before leaving this page though, scroll down to the second table to see results taken from the centre of each frame, followed by a set of results comparing the new zooms against the EF-S 18-55mm IS kit lens.

Closing the aperture slightly to f4 sees a small improvement in sharpness on both lenses, and it's at this point the EF-S 17-85mm IS joins in, albeit looking softer and less contrasty than the other two.

All three lenses improve in sharpness and contrast at f5.6, and this is arguably the sweetspot for the EF-S 15-85mm IS USM centre performance when zoomed-out. That said, the corner performance above looked a little better at f8, so it's a case of finding a balance in-between these two values or adjusting, depending on the subject matter.

Either way, the EF-S 15-85mm IS USM delivers excellent performance across the frame when fully zoomed-out and is a significant improvement over the older EF-S 17-85mm IS USM in this respect. But again this page only compares the lenses at their widest focal lengths and the story changes as you zoom-in. So check out our corner and centre results at 50mm, or first have a browse below at how the EF-S 15-85mm IS USM and EF-S 18-135mm IS compare against the EF-S 18-55mm IS kit lens.

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To compare real-life sharpness when zoomed-out, we shot this scene with the Canon EF-S 15-85mm IS, EF-S 18-55mm IS and EF-S 18-135mm IS, using an EOS 7D body at all apertures. The 7D was set to RAW to avoid in-camera JPEG corrections; all files were processed in Canon DPP with lens corrections disabled and the default sharpness of 3. IS was disabled on each lens, and magnified assistance in Live View used to confirm the focusing.

The first table compares crops taken from the corner of each image at different aperture settings and the second table compares crops taken from the centres of the same images.

While we matched the coverage as closely as possible for our tests at 50 and 85mm, we decided to test each lens on this page when fully zoomed-out. As such, each captured a slightly different field-of-view at their widest focal lengths of 15 and 18mm. This poses an issue when it comes to choosing an area to crop from the corner, as subjects close to the edges of the 18mm sample will be comfortably further-in on the wider lens, giving it an unfair advantage. As such we have taken our corner crops below from an area pressed up against the far right edge of each frame, and very close to the bottom.

The areas may not show the same subject area as a consequence, but they do allow us to compare overall sharpness and correction from the same portion of the frame. Below this table you'll see crops taken from close to the centre of each image and again the variations in focal length have resulted in slightly different areas being captured.

Zoomed-out, the EF-S 18-55mm IS kit lens suffers from softness and coloured fringing in the corners at all apertures tested, although it does improve slowly towards f8. The EF-S 18-135mm IS enjoys a step-up in sharpness in the corners over the kit lens, but again it's the EF-S 15-85mm IS USM which features the best performance of all here – as you'd hope considering its much higher price.

The EF-S 18-55mm IS kit lens does however redeem itself in the centre, delivering a respectably sharp result even with the aperture wide open – indeed it looks a little better than the EF-S 18-135mm IS at f3.5. As the apertures close down, there's little to tell the EF-S 18-55mm IS and EF-S 18-135mm IS apart, although again the EF-S 15-85mm IS USM enjoys a small edge in overall crispness.

Now check out how the four lenses tested here compare at a mid focal length of 50mm.