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To compare real-life sharpness at a mid focal length of 50mm, 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.

As before, the sequence starts with the EF-S 15-85mm IS USM and EF-S 18-135mm IS, this time both offering a maximum aperture of f5.0 at 50mm. It doesn't take a pixel-peeper to see the EF-S 15-85mm IS USM delivering a much sharper result in the corner, but the big surprise comes at f5.6 when the EF-S 17-85mm IS USM comes in.

While the EF-S 15-85mm IS USM remains comfortably sharper than the EF-S 18-135mm IS at f5.6, the older EF-S 17-85mm IS USM is sharper still, delivering a very impressive result at 50mm with its aperture wide open.

With the apertures closed to f8, the EF-S 15-85mm IS USM manages to essentially match the corner sharpness of the EF-S 17-85mm IS USM, although both remain comfortably ahead of the EF-S 18-135mm IS. The latter has at least improved as the aperture closed down, but the other two models remain superior in corner sharpness at a mid-range focal length 50mm. The really impressive result comes from the EF-S 17-85mm IS USM this time at f5.6, although again close it and the EF-S 15-85mm IS USM down to f8 and both come pretty close.

Scroll down to see how the three lenses compare in the centre of the frames, or lower still to see how the EF-S 18-55mm IS kit lens measures-up at this focal length. Or if you've already seen enough, head on over to our results at 85mm.

Scroll down to see how the EF-S 18-55mm IS kit lens measures-up at 50mm, or if you've already seen enough, head on over to our results at 85mm.

Support this site by shopping below

To compare real-life sharpness at a mid focal length of 50mm, 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.

As before, the sequence starts with the EF-S 15-85mm IS USM and EF-S 18-135mm IS, this time both offering a maximum aperture of f5.0 at 50mm. Once again the pricier EF-S 15-85mm IS USM enjoys a noticeably superior result with the aperture wide open.

With the apertures closed to f5.6, the EF-S 18-55mm IS kit lens can join-in, and while it unsurprisingly doesn't match the outstanding result from the EF-S 17-85mm IS USM above, it does manage to visibly out-perform the EF-S 18-135mm IS.

At f8, the gap has narrowed considerably between the EF-S 18-55mm IS and EF-S 18-135mm IS, although the EF-S 15-85mm IS remains comfortably in the lead of this particular threesome. This marks the end of our comparisons with the EF-S 18-55mm IS, but check out our next results page to see how the main three lenses measure-up at a short telephoto focal length of 85mm.