Canon EF-S 18-55/3.5-5.6 Lens Review

Performance at 18mm and 20mm

First let's take a look at the "lens testing range" that I used. It's actually mostly my neighbor's garden, but it provides a convenient subject with detail in the center of the image and tree branches against the sky in the top corners.

Note that the images were shot over several days, so there maybe a change from sunny with blue skies to cloudy with gray skies, however all the shots at any particular focal length were taken under the same conditions.

All the shots in this review, at all apertures and focal lens and with all lenses, were taken with the camera mounted on a tripod to ensure maximum stability.

The areas outlined in yellow on the first image below are those used in the test at 18mm. At other focal lengths the center was the same, but different branches occupied the top corners of the frame.

Since I don't have any other lenses that cover 18mm, the test at 18mm was done using only the 18-55 lens, shot at apertures from wide open (f3.5) to f16. The first set of images below shows the center performance as a function of aperture. It's pretty clear that it doesn't change much. I think there is a hint of sharpening going from f3.5 to f5.6 and a hint of softening going from f5.6 to f16, but you have to look hard to see a difference.

However, as shown below, the situation in the corner of the frame is quite different. Wide open the image is pretty soft. Stopping down only 1/3 stop to f4 shows a perceptible improvement, but it's still soft. Stopping down one more stop to f5.6 shows a large change with the image sharpening up significantly. Stopping down another stop to f8 again shows an improvement, but further reduction of aperture to f11 and f16 doesn't really buy you any more sharpness.

So overall, at 18mm the lens is good in the center but poor in the corner when wide open. Best performance comes at f8. Stopping down to f16 doesn't get you any more corner sharpness, but does soften the center of the image slightly. Conclusion: At 18mm shoot at f8 or f11 for best image quality. Image quality under those conditions is certainly quite acceptable.

20mm

I did have a 20-35/3.5-4.5 on hand, so at 20mm I was able to compare the two lenses directly. Note the image magnification here is quite a bit higher than that used for the 18mm test to better show the differences between these two lenses.

First let's look at the corner of the image:

It's pretty obvious here that the corner image quality is still pretty bad wide open for the 18-55 lens. The 20-35 is a lot better. Stopping down to f8, the 18-55 gains a lot of sharpness and the 20-35 gains a little. The 20-35 is better at both apertures.

Below are sections from the center of the image:

Here all the images are pretty similar, though the 20-35 is maybe a little softer than the 18-55 at f4. Differences in the center of the frame are much lower than at the image corners. I'd say the 18-55 maybe has a very slight edge here, not bad for a $100 lens! Again the 18-55, when stopped down a bit, is a decent lens.

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