The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Fujifilm XF 100-400mm F4.5-5.6 and the Olympus 300mm F4 IS Pro 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. Olympus 300mm F4 IS Pro is the longer of the two lenses at 227mm. The Fujifilm XF 100-400mm F4.5-5.6 with a length of 211mm, is 16mm shorter. On the other hand, the Fujifilm XF 100-400mm F4.5-5.6 has a larger diameter of 95mm compared to the Olympus 300mm F4 IS Pro's 93mm 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. Olympus 300mm F4 IS Pro weighs 1270g, 7% (105g) lighter than the Fujifilm XF 100-400mm F4.5-5.6's weight of 1375g.
Filter Threads
Both the Fujifilm XF 100-400mm F4.5-5.6 and the Olympus 300mm F4 IS Pro have the same Filter thread size of 77mm.
Below are links to the 77mm filters that we recommend you to consider for these lenses:
Lens Mounts
The Fujifilm XF 100-400mm F4.5-5.6 has the Fujifilm X lens mount whereas the Olympus 300mm F4 IS Pro has the Micro Four Thirds lens mount. Some of the latest released cameras that are compatible with these mounts are Fujifilm X-S20, Fujifilm X-T5 and Fujifilm X-H2 for the Fujifilm X Mount and OM System OM-1 II, Panasonic G9 II and OM System OM-5 for the Micro Four Thirds Mount.
Focal Range
Fujifilm XF 100-400mm F4.5-5.6 has a focal range of 100-400mm and
4.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
150-600mm when used on a APS-C / DX format camera.
On the other hand, the Olympus 300mm F4 IS Pro is a prime lens with fixed focal lenght of 300mm which has an effective (full-frame 35mm equivalent) focal range of 600mm when used on a FourThirds format camera.