These photos are tests of the 17-85 EF-S 4-5.6 IS kit lens that came with my Canon 20D DSLR. The lens is generally regarded to be good, but not great.

The four images here are full-size (with only minor cropping on the 38/40mm files) and compare my kit lens to a friend's 17-40L f4 lens which is a very highly regarded one. Both lenses were used on my 20D.

While this was not a scientific test, done on the friend's patio one evening as the light was fading, I was surprised at how well my kit lens compared to his lens, which was L glass and supposedly much higher quality, and therefore more expensive, and had no IS and half the zoom range.

So, in essence I've traded some vignetting and more CA (both of which are removable in Photoshop and surprisingly there *was* CA in the L lens, just less of it) and corner softness in the 17-85 (which is not removable) at full wide angle for longer zoom range and image stabilization, which to me is a worthwhile compromise, especially since the differences in image quality lessen as the aperture is stopped down on the kit lens to the f8 to f11 range that I normally use.

The last two images show how the lens works in a typical low light setting and its detail at fairly wide open aperture where depth of field is not a big factor.