With the large maximum aperture, excellent background blur is possible even with a fast shutter speed. The aspherical lens element makes the lens compact and corrects spherical aberrations. The image is sharp even at the edges. Lead-free glass is used.
1 The best non-L-series lens for this focal length.
I love this lens. Excluding Canon's L-series professional lens offerings (which are all considerably more expensive), this is the sharpest lens I have seen from them. I use it primarily for long-exposure night photography to get wide-angle sky shots. The fast optics allow for short enough exposures that I don't need a wedge to avoid star trails.
It's also very compact and light, making it an easy lens to carry around for general use. With my 300D DSLR and its inherent 1.6x crop, the lens has an effective 45mm focal length, which makes it a good general-purpose lens. Its portability combined with its good performance in low light make it the perfect lens for candid indoor photography.
