The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Canon 85mm f1.8 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 a crucial factor to consider when comparing two lenses. Canon 75-300mm f4.0-5.6 III is the longer of the two lenses at 122mm. The Canon 85mm f1.8 USM with a length of 72mm, is 50mm shorter. On the other hand, the Canon 85mm f1.8 USM has a larger diameter of 75mm compared to the Canon 75-300mm f4.0-5.6 III's 71mm 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 85mm f1.8 USM weighs 425g, which means it is 55g (11%) lighter than the Canon 75-300mm f4.0-5.6 III which has a weight of 480g.
Filter Threads
Both the Canon 85mm f1.8 USM and the Canon 75-300mm f4.0-5.6 III 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 85mm f1.8 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 Blackmagic URSA 12K LF, Z CAM E2-F6 II 6K and Z CAM E2-S6 II 6K.
Focal Range
Canon 85mm f1.8 USM is a prime lens with fixed focal lenght of 85mm. When it is mounted on an APS-C sensor camera with 1.6x crop, it provides a 35mm (FF) equivalent of
136mm.
On the other hand, the 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.
