> I've used Sigma lenses for many years and never had any problem with them in manufacture or optical quality except - and this is a possible issue - at extremes of settings and then only with one lens Many of their lenses beat main camera manufacturers' lenses for quality... and definitely for price. > Any manufacturer with Sigma's ongoing success has got to have something going for it. And certainly Nikon's extortionate prices do it no favour. They certainly don't offer absolutely reliable consistency. At the end of the day, read the reviews, handle them and don't take anyone's opinion above your own. > Howard I've had three Sigma lenses - sadly only one of them works now, unlike my 6 Canon ones which are all fine. Whatever the tests say, you are right, try them for yourself. I have and was forced to admit (painful on the old pocket!) that Sigma was a false economy for me. The qulity does not match the real thing. YMMV as they always say though ...