Sometimes you just don't have another option but to buy a third party lens. For example, the Canon EF-S 18-200 came out just last year, along with 50D. Sigma and Tamron have been making those for literaly years and in my opinion are ahead of Canon in superzoom category. Current Tamron is 18-270mm, image stabilised, and latest model from Sigma is 18-250, image stabilised, with ultrasonic focusing motor. As far as IQ, all lenses are more or less similar, but both Tamron and Sigma have reach advantage over Canon and Sigma focuses veeeery quietly.


Currently I ownthe latest Sigma model, which I use mostly on my XSI, when I have to go light and cannot change lenses.Being aware of the shortcomings of a superzoom, Iam very satisfied with what the lens offers.


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