For my amateur hobby shooting I prefer zooms with constant aperture along with a few portrait primes. So I might carry a 28-75mm f2.8 or a 70-200 f4 IS, and maybe a 35mm f2 or 50mm f1.4 for low light and portraits. I've read up on some reviews and wanted to give the 15-85mm a try after many positive recommendations. I found a great seller on Amazon who sent a mint 15-85mm with hood+b&w uv filter for an outrageously low price of $700! Still, it cost almost double than my Canon 18-135mm IS and I doubted if it's optical quality was really worth the price. IT IS! The image quality is simply superb! Granted, its variable aperture suggests optimum performance outdoors and a little more consideration to depth of field effects, but it is vastly superior to the 18-135mm (and the 28-135mmm) in terms of clarity and color. It is incredibly sharp for a non-L lens, and the auto-focus is quick and accurate. I could not give it 5 stars due to the zoom creep (which happens between 24-50mm). All lenses have some degree of zoom creep but for some reason (perhaps due to its weight), the zoom creep on this one happens rather fast between 24mm and 50mm. Don't be alarmed, there is no zoom creep at 15mm or 85mm, so unless there is traction to either push in or pull out the lens, the lens will stay pretty much in place at its extreme. It's really no big deal, your hand is usually on the barrel countering any zoom creep. My other option was to go with the even more expensive 17-55mm f2.8 but I like a little more reach and some opportunity to go wide. The 15-85mm is just the perfect walkaround zoom for my needs. If they made a 15-85mm f2.8, I'd be the first to get it but it would probably be a monster of a lens with a matching monster price tag. I haven't done much testing on the IS, but I've handheld the 15-85mm in the low tenths and have gotten some pretty good results. I'd like to say that the 18-135mm IS is comparable but I will say that the 28-135mm IS is not as good and a little lacking (it is a much older model, so IS must have improved over the years). The retail price could be a little cheaper but until the competition can come up with a lens with the same range and IQ, this Canon 15-85mm is the one beat (come on Tamron, I know you can do it!).
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