What 100-400mm at f/5 actually gives you
100-400mm is the classic portrait range — long enough to compress features flatteringly without forcing you across the room.
f/5 is a slow maximum aperture, so this leans on good light or on a stabilised body.
Size and filters
At 1140g (2.51 lb) it has real presence on the front of a camera, though it stays hand-holdable for a session.
Filters are 67mm — worth checking against what you already own, since polarisers and ND filters at this size are reusable across any other lens sharing the thread.
Autofocus, stabilisation and weather sealing
Autofocus is driven by an HLA motor.
Optical stabilisation is built in, which stacks with in-body stabilisation on bodies that have it and does the work alone on bodies that do not.
The barrel is weather-sealed, so rain and dust are a manageable risk rather than a reason to pack up.
