Pros Excellent resolution especially at the extremes of 10 and 20mm
Cons Some distortion at 10 to 12 mm. But as with all super wide angle lenses quite acceptable
Summary I purchased this lens about a month and a half ago and have already used it for an eight page fashion story for LINEA Magazine. I am impressed with how sharp it is at the two extremes i.e. at 10 and 20 mm. I love how wide it goes. It reminds me of the Canon 16-35 full frame lens. It is extremely sharp stopped down 2/3 rds to 1 stop at all apertures. The construction is robust as is the finition. Purchase an excellent filter for this lens and keep it clean. Dust will show up in the photos if stopped down to F22. I use a Hoya Pro1 UV that stays on the lens at all times.
Don't hesitate to purchase this lens. It is a keeper. It can be used on the Canon D1 with vignetting at 11 mm and full frame with vignetting at around 12.5 to 13mm. Not bad at all.
One more thing. Being of EX quality, I would go as far as to say that it is comparable to "L" glass.
Pros Sharp image quality
Cons Heavy and bulky but worth it
Summary This is a great performing lens which is versatile, allowing the user to be creative
"Great Lens"on by adrianhui
Pros The AF is silent, fast. Value for money, (comes with lens hood and carrying case) build quality is very good, feels solid.
Cons The quality is relative lower than buying the canon 10-22mm 3.5. But still good enough. The aperture is not as wide as the canons 3.5 which i think make quite a big difference.
Summary This is a great lens for the price you pay. just keep it in the 12-20mm range and the pictures will look amazing. This lens is great for outdoors but once its taken indoors the aperture is not large enough to take nice shots.