The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 100-400mm f4.5-5.6L IS II USM and the Canon 55-250mm f4-5.6 IS II 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 100-400mm f4.5-5.6L IS II USM is the longer of the two lenses at 193mm. The Canon 55-250mm f4-5.6 IS II with a length of 108mm, is 85mm shorter. Besides being longer, the Canon 100-400mm f4.5-5.6L IS II USM also has a larger diameter of 94mm compared to the Canon 55-250mm f4-5.6 IS II'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 II weighs 390g, 75% (1200g) lighter than the Canon 100-400mm f4.5-5.6L IS II USM's weight of 1590g.
Filter Threads
The Canon 100-400mm f4.5-5.6L IS II USM has a filter size of 77mm whereas the Canon 55-250mm f4-5.6 IS II 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 77mm filters that we recommend you to consider for the Canon 100-400mm f4.5-5.6L IS II USM:
And these are the 58mm filters that we recommend for the Canon 55-250mm f4-5.6 IS II:
Lens Mounts
The Canon 100-400mm f4.5-5.6L IS II USM has the Canon EF lens mount whereas the Canon 55-250mm f4-5.6 IS II has the Canon EF-S lens mount. Some of the latest released cameras that are compatible with these mounts are Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount and Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount.
Focal Range
Canon 100-400mm f4.5-5.6L IS II USM has a focal range of 100-400mm and
4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
160 - 640mm.
On the other hand, the Canon 55-250mm f4-5.6 IS II 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.