The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 20mm f2.8 USM and the Canon 16-35mm f4L IS 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 16-35mm f4L IS USM is the longer of the two lenses at 113mm. The Canon 20mm f2.8 USM with a length of 71mm, is 42mm shorter. Besides being longer, the Canon 16-35mm f4L IS USM also has a larger diameter of 83mm compared to the Canon 20mm f2.8 USM's 78mm 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 20mm f2.8 USM weighs 405g, which means it is 210g (34%) lighter than the Canon 16-35mm f4L IS USM which has a weight of 615g.
Filter Threads
The Canon 20mm f2.8 USM has a filter size of 72mm whereas the Canon 16-35mm f4L IS 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 Canon 20mm f2.8 USM:
And these are the 77mm filters that we recommend for the Canon 16-35mm f4L IS USM:
Lens Mounts
Both the Canon 20mm f2.8 USM and the Canon 16-35mm f4L IS 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
Canon 20mm f2.8 USM is a prime lens with fixed focal lenght of 20mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
32mm.
On the other hand, the Canon 16-35mm f4L IS USM has a focal range of 16-35mm and 2.2X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 25.6 - 56mm.