This lens has a field of view equivalent to an 80-240mm lens on a full frame body. Traditional options in this range are 70-200mm lenses which have a field of view equivalent to a 112-480mm lens. This Sigma is a very nice lens but I found it a bit lacking for field sports back in the Fall. Where it excels, however, is indoor events where the range between 50mm and 70mm (80-112mm equivalent) can be quite useful and where the extreme long end of the 70-200mm is usually not needed. The optical stabilization also helps with slower shutter speeds which are sometimes necessary with indoor events.
So, I decided to use the Sigma for a flute choir concert yesterday. My kit was the Sigma lens, a Canon 7D body and a Canon EF-S 24mm f/2.8 pancake lens. Here are a few that show the range of the Sigma lens. For all the photos you may visit http://trulandphoto.zenfolio.com/cafc.
|50mm, f/2.8, 1/60 sec., ISO 1600|
|76mm, f/2.8, 1/60 sec., ISO 1600|
|118mm, f/2.8, 1/90 sec., ISO 1600|
|150mm, f/2.8, 1/90 sec., ISO 1600|
So, since this lens has been discontinued by Sigma I think I'll hang on to it for events like this. For outdoor sports, a non-IS Canon 70-200mm f/2.8L will do fine.