What 5mm at f/2.8 actually gives you
At 5mm this sits in ultra-wide territory, where straight lines near the frame edge stretch noticeably and a small step forward changes the composition a lot.
f/2.8 is the working standard for a fast lens — a stop or two of low-light headroom over a kit zoom, and noticeably more background separation.
Size and close focus
At 395g (13.9 oz) it sits in the middle for handling: substantial enough to feel planted, light enough not to dominate the kit.
It focuses to 13cm, which is close enough to fill the frame with small subjects.
Autofocus, stabilisation and weather sealing
Autofocus is driven by a Nano USM motor.
There is no optical stabilisation in the lens, so handheld steadiness depends on the body having IBIS, or on keeping the shutter speed up.
The barrel is weather-sealed, so rain and dust are a manageable risk rather than a reason to pack up.
