The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 18-135mm F3.5-5.6 IS and the Canon 18-55mm f3.5-5.6 for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Canon 18-135mm F3.5-5.6 IS is the longer of the two lenses at 96mm. The Canon 18-55mm f3.5-5.6 with a length of 80mm, is 16mm shorter. Besides being longer, the Canon 18-135mm F3.5-5.6 IS also has a larger diameter of 77mm compared to the Canon 18-55mm f3.5-5.6's 69mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Canon 18-55mm f3.5-5.6 weighs 190g, 63% (325g) lighter than the Canon 18-135mm F3.5-5.6 IS's weight of 515g.
Below you can find the dimension and weight table of the Standard Zoom Lenses in Canon EF-S Mount for size comparison purposes.
Standard Lenses in Canon EF-S Mount for Size Comparison
Filter Threads
The Canon 18-135mm F3.5-5.6 IS has a filter size of 67mm whereas the Canon 18-55mm f3.5-5.6 has a 58mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Canon 18-135mm F3.5-5.6 IS:
And these are the 58mm filters that we recommend for the Canon 18-55mm f3.5-5.6:
Lens Mounts
Both the Canon 18-135mm F3.5-5.6 IS and the Canon 18-55mm f3.5-5.6 has the same Canon EF-S lens mount. Some of the latest released cameras that are compatible with the Canon EF-S lenses are Canon T8i, Canon 90D and Canon SL3.
Canon 18-135mm F3.5-5.6 IS is also available in Canon EF-S mount.
Focal Range
Canon 18-135mm F3.5-5.6 IS has a focal range of 18-135mm and
7.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-216mm when used on a APS-C / DX format camera.
On the other hand, the Canon 18-55mm f3.5-5.6 has a focal range of 18-55mm and 3.1X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-88mm when used on a APS-C / DX format camera.