The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 90-300mm f4.5-5.6 and the Canon 75-300mm f4.0-5.6 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 75-300mm f4.0-5.6 III USM is the longer of the two lenses at 122mm. The Canon 90-300mm f4.5-5.6 with a length of 115mm, is 7mm shorter. On the other hand, there is no difference between the max diameters of these lenses, both coming at 71mm.
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 90-300mm f4.5-5.6 weighs 420g, which means it is 60g (12%) lighter than the Canon 75-300mm f4.0-5.6 III USM which has a weight of 480g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Canon EF Mount for size comparison purposes.
Telephoto Lenses in Canon EF Mount for Size Comparison
Filter Threads
Both the Canon 90-300mm f4.5-5.6 and the Canon 75-300mm f4.0-5.6 III USM have the same Filter thread size of 58mm.
Below are links to the 58mm filters that we recommend you to consider for these lenses:
Lens Mounts
Both the Canon 90-300mm f4.5-5.6 and the Canon 75-300mm f4.0-5.6 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
Canon 90-300mm f4.5-5.6 has a focal range of 90-300mm and
3.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
144 - 480mm.
On the other hand, the Canon 75-300mm f4.0-5.6 III USM has a focal range of 75-300mm and 4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 120 - 480mm.