The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 55-250mm f4-5.6 IS STM and the Canon 18-135mm f3.5-5.6 IS STM 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 55-250mm f4-5.6 IS STM is the longer of the two lenses at 111mm. The Canon 18-135mm f3.5-5.6 IS STM with a length of 96mm, is 15mm shorter. On the other hand, the Canon 18-135mm f3.5-5.6 IS STM has a larger diameter of 77mm compared to the Canon 55-250mm f4-5.6 IS STM's 70mm 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 55-250mm f4-5.6 IS STM weighs 375g, which means it is 105g (21%) lighter than the Canon 18-135mm f3.5-5.6 IS STM which has a weight of 480g.
Filter Threads
The Canon 55-250mm f4-5.6 IS STM has a filter size of 58mm whereas the Canon 18-135mm f3.5-5.6 IS STM has a 67mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Canon 55-250mm f4-5.6 IS STM:
And these are the 67mm filters that we recommend for the Canon 18-135mm f3.5-5.6 IS STM:
Lens Mounts
Both the Canon 55-250mm f4-5.6 IS STM and the Canon 18-135mm f3.5-5.6 IS STM 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.
Focal Range
Canon 55-250mm f4-5.6 IS STM has a focal range of 55-250mm and
4.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
88-400mm when used on a APS-C / DX format camera.
On the other hand, the Canon 18-135mm f3.5-5.6 IS STM 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.