|Canon EF-S 18-135mm f/3.5-5.6 IS Specifications|
|Lens Construction (groups)||12|
|Lens Construction (elements)||16|
|No. of Diaphragm Blades||6|
|Closest Focusing Distance||0.45m (17.7")|
|Maximum Diameter x Length||75.4mm x 101mm (3" x 4")|
The Canon EF-S 18-135mm ƒ/3.5-5.6 is available as a kit lens option for several Canon camera bodies, and it makes an excellent all-purpose lens. For the money, it provides very good performance: it doesn't need to be stopped down excessively to provide sharp results, and results for distortion, light falloff and chromatic aberration aren't beyond the pale of what you'd expect in this category of lens.
the EF-S 18-135mm IS performs well for the price, but don't expect miracles. Like all lenses with long optical ranges, it suffers from quite noticeable geometric distortion and vignetting (although the latter can be effectively corrected using software or in-camera on recent bodies), and the corners are also soft at larger apertures.
The Canon EF-S 18-135mm f/3.5-5.6 IS may be somewhat better than the EF-S 18-200mm f/3.5-5.6 IS but it's not exactly a good lens either. The resolution makes a rather wild roller coaster ride through the different quality levels. Large aperture settings should be generally avoided at 18mm and beyond the middle range - the borders/corners are plain soft here.
If the EF-S 18-135 represents the extent of your budget, it is a good choice for capturing your memories. For a reasonably low price, the Canon EF-S 18-135mm f/3.5-5.6 IS Lens provides reasonable f/8 image quality over a wide focal length range in a relatively light weight/small package with image stabilization. It is a nice casual use lens for those on a tight budget.
As would be expected in a relatively inexpensive wide to tele zoom, there are some compromises which have to be made. The EF-S 18-135/3.5-5.6 IS shows vignetting wide open throughout the focal length range and distortion and CA at the wide end of the zoom range. Center sharpness is generally quite good, but the lens needs to be stopped down a stop or two at most focal lengths to maximize edge and corner image quality.