A comparison between the Sigma EX 70-200 f2.8L and Canon EF 70-200 f4L, f2.8L, f4L IS, f2.8L IS, f2.8 L IS II, 100-400 f4L IS, 75-300 IS, 70-300 IS DO, 70-300 IS and 70-300 L IS. Sigma EX 70-200 f2.8 HSM Optically, this is at the top end. A little soft wide open, by f4 it is just as sharp as the Canon L lenses. Focus is quiet, but very slightly slower than the Canon lenses. Build quality is superb. There's always a slight risk when buying Sigma lenses that they will not be compatible with future cameras - this one has so far stood the test of time, though. The lens is heavier than the non-IS f4L Canon lens, but lighter than the f2.8. If you need f2.8 on a budget, this is the lens to buy. Canon EF 70-200 f4L Again, optically superb. This lens has all the benefits of Canon's L series, but is much more reasonably priced than the others. If you don't need IS, f2.8 or 300mm, this is the lens to buy. Canon EF 70-200 f4L IS The lens above with IS and arguably even better optics. Perhaps a little pricey, but a very interesting lens. Canon EF 70-200 f2.8L Excellent optically, even at f2.8 - and it's a Canon L lens. Probably only the best choice if you want to work regularly at f2.8, don't need IS and insist on Canon. Canon EF 70-200 f2.8L IS No longer the best f2.8 option, but significantly cheaper than the Mk II lens. Canon EF 70-200 f2.8L IS Mk II Even better than the original - one of the best zooms on the planet. Horribly expensive, but staggeringly good. Canon EF 100-400 L IS This is not as good optically as the 70-200 options, but if you want 400mm in a zoom package it's a very popular option, and probably better than a 70-200 and 2x extender. Usual L build quality, but this is a trombone action zoom - something of a rarity these days, and an aquired taste in the handling department. Expensive, but probably the best option if you need to be working at the 300-400mm end. Canon EF 70-300 IS USM Build quality is considerably less than the lenses above, AF is not the most rapid and although optically very good indeed, it doesn't quite reach the standard of the above lenses. However, it's cheaper, much lighter and more compact, and is well worth considering for travel etc. Better than it should be, and if you need 300mm and don't need top build quality or the very best optical quality, a great choice. Canon EF 70-300 DO IS Very similar optical performance to the non-DO lens, but at twice the price. However, the build quality is better than the cheaper lens, and it's shorter (but heavier). Because of the Diffractive Optics and 6-blade iris rather than the 8-bladed one of the cheaper lens, some have said the bokeh of this lens is not as good. Buy if you need a smallish, fairly tough lens that goes to 300mm. Canon EF 70-300 L IS USM Yet another 70-300? Variable maximum aperture? Won't take extenders? Yes, yes and yes; however, it's fairly compact, covers a decent range, has excellent AF and is optically superb - right up there with the best. Buy if you want the very best 70-300. Canon EF 75-300 IS USM This was Canon's first IS lens, and is basically the pretty cheap 75-300 lens with IS fitted. It has been replaced by the 70-300 IS, and is no longer available new. The IS isn't as effective as more recent versions, and optically it's the weakest lens of the selection, particularly at 300mm - however, it's perfectly adequate for most uses especially from 70-200mm. Worth considering if you can find a good-condition second hand example for a fairly low price. Canon EF-S 55-250 IS USM An absolute bargain for cropped sensor users - excellent quality for the price.