Summary: I primarily shoot with a 50mm and canon 5D camera. After trying several wide angle lenses, I opted for this lightweight wide angle zoom given the price point and ease I carrying it all day. I will mostly using this for landscapes and architecture photography. There is some distortion but that can easily be fixed with photo software in post production. Photos so far are sharp and the field of view works well for me.
Summary: I use this lens all the time and am very pleased with the image quality and ease of use. One thing you should be sure of is whether this will work on your EOS camera. Because sensor my 40D has, it cannot take advantage of super wide angle lenses. The more professional series camera bodies are designed to take advantage of the widest angle lenses. With that said, I highly recommend this lens.
Summary: I use a T3i crop sensor camera and wanted a 35mm equivalent mainly for video work. I use this lens about 50/50 for photo and video. This one since it functions like a 32mm I find it is a very versatile focal length. I find it to be great in low light, vivid color, and sharp at 2.8. There is barely perceptible barrel distortion on the crop sensor camera. Overall I love this lens and would suggest it for both photography and video for a crop sensor camera.
Conclusion: I purchased this lens used (1 month old )and was a little cautious about it's value.Took some pictures and was very pleased.Having other wide angle Len's to compare with 24-105,24-85 and17-40 I can say this 20mm lens is as good or better tan most of the other lens.I like the build quality and how light it is and it is very sharp.My 5D mark 3 helps with it's lens correction.
Summary: Preloved. Images are crisp and sharp. Good for budding photographers. Served me well for almost 2 years. Sold as changed gears to M4/3 for weight reduction. Package arrived as promised. Well packed.
Summary: This lens has become my primary lens. I brought it on vacation to Mexico and was able to capture awesome pictures. It's definitely worth the $$... It's not expensive like the l-series, but I can't complain for the $$ I paid for it... It also is nice for video capture... Love it!