What 27mm at f/2.8 actually gives you
27mm sits close to the way the eye takes in a scene, which is why this range tends to get used as a general-purpose focal length. On the APS-C bodies it covers, it frames like 41mm would on full-frame.
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 filters
At 85g (3.0 oz) it is light enough that it stops being a decision — the kind of lens that stays on the body or in the bag without thought.
Filters are 43mm — 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 and stabilisation
Autofocus is driven by an STM 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.
