between the models and capabilities. A number of magazines recently have done a big zoom coparison and in both the Canon mag and the Nikon mag the Sigma 150-500 came out to and in the Canon one even beat the 100-400. On a more personal touch i had the 100-400 and got to the stage where is almost preyed before getting it out of the bag it would be ok and although it never failed me ( i always had the screww slackened right off when using ) i could not take it any longer so chopped it in ( although wife thinks i went a little to far as i chopped everything in and went to Nikon ). Olicat wrote: 1 month and 470 later and I now have a lovely, smooth, good-as-new 100-400! Good to hear. My tale is similar to others in that I unwittingly paid 850 off ebay for a 10 year old 100-400! Within a year it was in at H Lehmanns for a 160 service which became a 300 bill when the 'O' ring was diagnosed as knackered. Shortly afterwards the damn thing seized up on me again so went back to Lehmanns under warranty and is now back in my care in full working order. Don't get me wrong I wouldn't be without it and I treat it as I did my first born - but I've learned a few hard lessons about so called ebay bargains! Top tip - if you are