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 EF 400mm F2.8L IS III USM 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 EF 400mm F2.8L IS III USM is the longer of the two lenses at 343mm. The Canon 55-250mm f4-5.6 IS STM with a length of 111mm, is 232mm shorter. Besides being longer, the Canon EF 400mm F2.8L IS III USM also has a larger diameter of 163mm 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 2465g (86%) lighter than the Canon EF 400mm F2.8L IS III USM which has a weight of 2840g.
Filter Threads
The Canon 55-250mm f4-5.6 IS STM has a filter size of 58mm whereas the Canon EF 400mm F2.8L IS III USM has a 52mm 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 52mm filters that we recommend for the Canon EF 400mm F2.8L IS III USM:
Lens Mounts
The Canon 55-250mm f4-5.6 IS STM has the Canon EF-S lens mount whereas the Canon EF 400mm F2.8L IS III USM has the Canon EF lens mount. Some of the latest released cameras that are compatible with these mounts are Canon T8i, Canon 90D and Canon SL3 for the Canon EF-S Mount and Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K for the Canon EF Mount.
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 EF 400mm F2.8L IS III USM is a prime lens with fixed focal lenght of 400mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 640mm.
