After reading the different reviews of the "Sigmonster" I found for myself that this review was the most helpful, by Bill Majoros.


http://www.billmajoros.com/photoalbum/categories/new/Canon600/windows/index.html





A second review I found also very helpful was from Romy Ocon from my wife's native land of the Philippines, where we travel & I photograph every couple of winters.


http://www.pbase.com/liquidstone/image/58879465/original





You can see that both test have similarity but there does seem to be some differnce's in equipment used so that has to be taken into account. Ofcorse I could be wrong on that assement and I just got things confused after going through all of the reviews. After reading these two my inpression is that the Canon Prime lens's are a bit sharper with IS and focusing limitor while the Sigmonster does not have either. If you want the flexibility of a zoom of this size the Sigmonster seems to be favored, but I would personaly tend to lean towards the Canon lens.


I would still like to see a review by Brian, as I like his assement methods compared to many others that are not so deliberate in metodology, which he ofcourse is!!