The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 16-35mm f4L IS USM and the Canon 16-35mm F2.8L III for their suitability to various photography scenarios:
Size and Weight Comparison
Size of a lens is an important deciding factor when comparing two lenses.Canon 16-35mm F2.8L III is the longer of the two lenses at 128mm. The Canon 16-35mm f4L IS USM with a length of 113mm is 15mm shorter. Besides being longer, the Canon 16-35mm F2.8L III also has a larger diameter of 89mm compared to Canon 16-35mm f4L IS USM's 83mm diameter.
Weight of a lens is as important as its external dimensions, especially if you are planning to hand hold your camera and lens combination for longer periods. Canon 16-35mm f4L IS USM weighs 615g, which means it is 175g (22%) lighter than the Canon 16-35mm F2.8L III which has a weight of 790g.
Below you can find the dimension and weight table of the 'Wideangle Zoom Lenses in Canon EF Mount for size comparison purposes.
Wideangle Zoom Lenses in Canon EF Mount for Size Comparison
Both Canon 16-35mm f4L IS USM and Canon 16-35mm F2.8L III 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.
Both lenses have the same focal range of 16-35mm but while Canon 16-35mm f4L IS USM has the fastest aperture of F4.0, the Canon 16-35mm F2.8L III's widest aperture value is F2.8.