The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon EF 70-300 F4-5.6 IS II USM and the Canon 75-300mm f4.0-5.6 III for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is an important deciding factor when comparing two lenses. Canon EF 70-300 F4-5.6 IS II USM is the longer of the two lenses at 146mm. The Canon 75-300mm f4.0-5.6 III with a length of 122mm, is 24mm shorter. Besides being longer, the Canon EF 70-300 F4-5.6 IS II USM also has a larger diameter of 80mm compared to the Canon 75-300mm f4.0-5.6 III's 71mm diameter.
The 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 75-300mm f4.0-5.6 III weighs 480g, 32% (230g) lighter than the Canon EF 70-300 F4-5.6 IS II USM's weight of 710g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Canon EF Mount for size comparison purposes.
Telephoto Zoom Lenses in Canon EF Mount for Size Comparison
Lens Mounts
Both the Canon EF 70-300 F4-5.6 IS II USM and the Canon 75-300mm f4.0-5.6 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.
Focal Range
Canon EF 70-300 F4-5.6 IS II USM has a focal range of 70-300mm and 4.3X zoom ratio . When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of 112 - 480mm.
Canon 75-300mm f4.0-5.6 III 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.