The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-250mm F3.5-6.3 DC OS HSM and the Canon 400mm f5.6L 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 400mm f5.6L USM is the longer of the two lenses at 257mm. The Sigma 18-250mm F3.5-6.3 DC OS HSM with a length of 89mm, is 168mm shorter. Besides being longer, the Canon 400mm f5.6L USM also has a larger diameter of 90mm compared to the Sigma 18-250mm F3.5-6.3 DC OS HSM's 74mm 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. Sigma 18-250mm F3.5-6.3 DC OS HSM weighs 470g, which means it is 780g (62%) lighter than the Canon 400mm f5.6L USM which has a weight of 1250g.
Filter Threads
The Sigma 18-250mm F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Canon 400mm f5.6L USM has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sigma 18-250mm F3.5-6.3 DC OS HSM:
And these are the 77mm filters that we recommend for the Canon 400mm f5.6L USM:
Lens Mounts
Both the Sigma 18-250mm F3.5-6.3 DC OS HSM and the Canon 400mm f5.6L USM has the same Canon EF lens mount. Some of the latest released cameras that are compatible with the Canon EF lenses are Canon T8i, Canon 90D and Canon SL3.
Sigma 18-250mm F3.5-6.3 DC OS HSM is also available in the Nikon F (DX) , Pentax KAF3, Sony Alpha, Sigma SA, Canon EF, Nikon F (DX), Pentax KAF3, Sony Alpha and Sigma SA mounts.
Focal Range
Sigma 18-250mm F3.5-6.3 DC OS HSM has a focal range of 18-250mm and
13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
28.8-400mm when used on a APS-C / DX format camera.
On the other hand, the Canon 400mm f5.6L 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.
