Canon released a new version of the non-stabilized EF-S 18-55 f/3.5-5.6 III lens in line with the new stabilized EF-S 18-55 f/3.5-5.6 IS II, the non-stabilized with likely to come on future lower-end Rebel models and higher-end Rebel models. The new version of the non-stabilized lens is much sharper than the older version, very similar to the new IS II version, only not having Image Stabilization. [3]
The EF-S 18-55/3.5-5.6 is an unusual Canon EOS lens. It was designed only to be mountable on the Digital Rebel (EOS 300D) body since it has a reduced image circle (enough for the Digital Rebel sensor, but not enough for full frame 35mm) and it sticks further into the camera body than a normal EF series lens. [Editor's Note: A variant of this lens is also part of the Canon Rebel XT when sold as a kit with a lens. That lens is called the Canon EF-S 18-55m f/3.5-5.6 II. It has been reported that the newer model has the same optics as the old model and the only differences are cosmetic.]
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.
The 18-55/3.5-5.6 is a very good lens for $100. It's weaknesses show up at the ends of its zoom range (18mm and 55mm), especially in the corners of the frame when used wide open where resolution and contrast can be rather poor. To get decent sharpness in the corners requires stopping to f8 at 18mm or f11 at 55mm - but you still won't get the same image quality as you would from a a prime or L series zoom lens. In the mid range (28mm), performance is pretty good at both center and edge. For a cheap, plastic mount, low end consumer lens, the 18-55 is certainly better than I would have expected. It's not a rival for an L series lens, but much of the time it can hold it's own against Canon's full frame coverage mid-range consumer lenses, especially in the center of the frame.
