I got the 18-135 IS when I bought my 7D so I thought I would write a quick mini review of the lens.
The lens is one of Canon’s newest EF-S lenses which are designed to work on the Canon APS-C sized sensor cameras (With EF-S mount).
The lens has the focal range (Equivalent in 35mm) of a 29-216mm lens and covers a 7x zoom range which puts it in the class of being a “Super zoom” lens.
The construction of this lens is decent, it doesn’t have the same quality as a L series lens, but it’s not priced like a L series lens and is quite reasonably priced. The 18-135 IS lens features a metal lens mount, and a real manual focus ring, but doesn’t have full time manual focusing which means you have to switch the AF/MF button to the manual focus setting if you plan on shooting in manual focus. The front of the lens doesn’t rotate, so using a polarising filter isn’t a problem with this lens.
The focus speed is quick, but it is a bit noisy because Canon have chosen to use a DC focusing motor rather then one of the Ultrasonic focusing motors. Focus seems quick enough under most situations, but it does slow down a bit when shooting in very low light/night (But so can the USM lenses) the zoom barrel is a single tube design (I prefer this over the duo cam design) and there isn’t any wobble in the barrel, and the lens feels tight, so zoom creep shouldn’t be a issue on this lens. The lens has a 67mm filter thread, and uses the same lens hood as the EF-S 17-85 IS lens.
The 18-135 IS features a 4 stop Image stabiliser which does seem to work very well, maybe not 4 stops, but seems to give you about 3 stops of extra handholdablilty which is better then having no IS at all.
The lens is not that heavy, and feels nice and balanced paired up with the 7D. This combo makes a nice light weight travel/walkabout setup, and covers a good focal range.
The picture quality is surprisingly good, even on the 18mp sensored 7D it manages to produce sharp and detailed photos, but don’t expect prime lens quality here (But then again, this is a 7x zoom lens). There is a bit of vignetting when shooting wide open at 18mm, and also at 135mm (It’s common with all the EF-S lenses, and even EF lenses vignette when used on a full framed camera) but stopping the lens down to f/8 and lower will soon fix the problem, and it’s only a problem under some circumstances, in most cases, you won’t notice it much anyway.
One thing that was a bit disappointing was my copy seemed to start showing lens creep with only a month of use. This is where the zoom barrel extends out by itself when you point the lens up or down (In my case, it was when the lens was pointed down). This problem is typical on allot of the “Super Zoom” lenses on the market. Canon didn’t add the zoom lock feature that is found on the EF-S 18-200 IS. While the zoom creep on this lens wasn’t to much of a issue, I think the lens could have been designed a bit better to keep the lens tighter just like the way the 15-85 IS has been designed, or Canon could have added the zoom lock to this lens. But this is only a minor issue, and I did have a lens hood attached.
Overall, this lens makes a great budget lens for someone looking at a cheap travel/walkabout lens, or maybe upgrading their 18-55 kit lens to something with a bit more range.