Its quite an old lens (discontinued) of sigma's. In good light it will produce some good results, autofocus on the slower side and definitely not on par with the canon 100-400mm. Depends how much you're willing to spend. Sigma replaced that lens with the 120-400mm OS which is definitely an improvement and can be picked up for £350-450, or if you only need 300mm the sigma 100-300mm f4 a fantastic lens and can be picked up for £300-400, very sharp, fast focusing and will take a sigma TC. As light drops off the sigma 80-400mm performance falls off significantly, but perhaps slightly improved by the more modern sensor/ISO technology of todays camera bodies. If you do purchase it, just work with its limitations. Not sigma's best lens by far and it depends what you want to photograph