I got my brand new Sigma 80-400mm OS and it had major focus issues and so, having already sold my Bigma, and now awaiting refund of £600 for the OS, I am looking afresh at my zoom options. The idea of the OS was to assist with hand held shots, particularly for a planned walking safari in Namibia end 2005, but I am a bit worries about getting another one now It MAY be fine, but importing from HK puts a single lens under potentially more risk of damage (I suspect the box was dropped at some point and an interior lens slightly misaligned as a result ... but who knows?!) One option is to forgo the OS and look at the 100-300 Sigma: f4 through the range, very well thought of, but I'm keen to see if anyone has this lens and what their experience is. I would buy it with the Sigma 1.4x extender, giving me 450mm ... not as long as the Bigma, but lighter to carry and also 50mm longer than the OS!! The Bigma I know about and it is an option. I don't want to spend out on the 100-400 IS.