|Canon EF 20mm f/2.8 USM Specifications|
|Lens Construction (groups)||9|
|Lens Construction (elements)||11|
|No. of Diaphragm Blades||5|
|Closest Focusing Distance||0.25m (9.8")|
|Maximum Diameter x Length||77.5mm x 70.6mm (3.1" x 2.8")|
If all you can afford is the Canon EF 20mm f/2.8 USM Lens, buy it and enjoy it. It will capture memories just fine.
As a wide-angle lens for cropped sensors, this lens falls a little short, with virtually all of the standard zooms giving a wider angle of view. However, on the full frame sensors that Canon are now producing, this lens still warrants its place in their line-up.
The EF 17-40mm f/4L lens is a very sharp, high contrast zoom lens with performance characteristics that often match and sometimes exceed those of quality prime lenses at wide angle.