I chose this lens over the Sigma equivalent because of the extra 4mm. It might not sound like much, but in this area 4mm can make a big difference. Paired with a Canon 60D with an APS-C sensor it allows you to shoot architecture, interiors or landscapes with much more flexibility than a lens that starts at 17mm or 18mm, which many kit lenses do. The first time I used this was filming stationary planes parked at an airfield during an air show. Planes can be difficult to shoot due to their shape and size. Also, with thousands of people walking around, it can be difficult to get an accurate shot when you have to move about 30 feet away. This lens handles wide-angle shots with little to no distortion. The glass is designed to minimize the keystone distortion that many wide-angle lenses exhibit when shooting from as little as 10mm. Zooming up to 24mm gives you a great shot with a 36mm equivalent angle compared to a 35mm lens.
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