Heavy vignetting, soft in the corners, but it's a good little lens if you are looking for something on the wide end.

If you were actively seeking a review of this lens, the chances are that you've already seen another one written by Mr Ken Rockwell, who I believe it's fair to say divides opinion on many photography matters.

Fast and accurate focus; sharp frame centre; attractive colour rendering

Soft corners; field curvature; colour fringing

20mm prime lenses aren't overly popular anymore these days - most people prefer ultra-wide zoom lenses or prime lenses with an even more extreme focal length. However, consider me to be a relic. I think that 20mm is actually a sweet spot in this focal length class.

Reasonably sharp wide-angle lens. There is slight red-green fringing, similar to 15 mm fisheye. Purple fringing is absent. Strong vignetting at f2.8-f4, but this goes away at f8 and higher. Good centre sharpness, but the corners are a bit soft at f2.8, and this improves by f5.6.

reasonably sharp; usm focus; excellent build quality; accepts 72 mm filters

vignetting; some CA; soft at f2.8

The Canon EF 20mm f/2.8 USM Lens fits in a nice wide angle focal length space below the ultra-common 24-something and 28-something zoom lenses. There is a noticeable FOV (field of view) difference between 20mm and 24/28mm. People often look for a prime lens for their ultra wide angle needs.

This 20mm is very good optically, and has superb ergonomics for use with both 35mm and today's full-frame digital SLRs . Its mechanical quality is superior to most of Canon's lenses today, with a metal filter ring, metal hood mount and metal forebarrel.

The focal length of this prime lens from Canon is on the edge of ultra wide angle when used on a full frame sensor or the 35mm film it was originally designed for. Even on a cropped sensor, it provides a good angle of coverage. We take a look at how it performs.

Good build and finish; Nice focal length on Full Frame cameras; Silent and fast autofocus; Good image quality

Not that useful on cropped sensors; Stiff manual focus ring (on example tested; Distortion worse than on modern designs (minor point; Hood not included with lens

I shoot with it on a Canon 40D. I bought this lens for shooting nightclubs and bands, in locations I did not want to risk taking my 24-105L lens. I intended this to be a cheap purchase that I could use at F4 to F5.6 combined with a bracket mounted flash to shoot clubs and events.

fast focusing even in low light; wide; great colors

I occasionally really miss shots because of focus being off

The Canon 20mm f/2.8 USM lens often catches a bad rap for being soft in the corners, having horrendous vignetting wide open, and being plagued with an overall lack of contrast. I'm here to tell you why absolutely none of that matters.

The optical construction is made of 11 elements in 9 groups without any special glass. The aperture mechanism features 5 blades. With a min. focus distance of 0.25m the max. object magnification is about 1:7. The lens feature a floating system for close focus correction.