I researched and purchased this lens on line from Wilkinson Cameras and was not disappointed, The price was below average high street prices and with a quick and free delivery service the lens was with me within 48hrs of placing the order. The lens it's self a bit heavy for me as a senior user but an adapted monopod and a decent tripod head ironed out any difficulties I had where weight was concerned. Clarity and sharpness at f/8-f/11 is outstanding and you would be hard pushed to tell this was a budget lens of Sigma's, Auto focus is quiet and positive. The smallest downside really is the amount of hand/wrist movement required to adjust from 150mm to 600mm but to date I have not missed out on any shots because I was to late in focussing. All in all a great product for the price and worry free with a three year guarantee if registered with Sigma on line.