The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 400mm f5.6L USM 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 400mm f5.6L USM with a length of 257mm, is 86mm shorter. Besides being longer, the Canon EF 400mm F2.8L IS III USM also has a larger diameter of 163mm compared to the Canon 400mm f5.6L USM's 90mm 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 400mm f5.6L USM weighs 1250g, which means it is 1590g (55%) lighter than the Canon EF 400mm F2.8L IS III USM which has a weight of 2840g.
Below you can find the dimension and weight table of the Telephoto Prime Lenses in Canon EF Mount for size comparison purposes.
Super Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
The Canon 400mm f5.6L USM has a filter size of 77mm 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 77mm filters that we recommend you to consider for the Canon 400mm f5.6L USM:
And these are the 52mm filters that we recommend for the Canon EF 400mm F2.8L IS III USM:
Lens Mounts
Both the Canon 400mm f5.6L USM and the Canon EF 400mm F2.8L IS III USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon 1D X III, Canon 6D MII and Canon 5D MIV.
Focal Range
Both lenses have the same focal range of
400mm but while Canon 400mm f5.6L USM has the fastest aperture of
F5.6, the Canon EF 400mm F2.8L IS III USM's widest aperture value is
F2.8.