What 45-175mm at f/4 actually gives you
45-175mm 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 Micro Four Thirds bodies it covers, it frames like 90mm would on full-frame.
f/4 is a moderate maximum aperture. There is less low-light headroom and less background blur than an f/2.8 lens gives, which is generally the trade for lower weight and cost.
Size and filters
At 210g (7.4 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 52mm — worth checking against what you already own, since polarisers and ND filters at this size are reusable across any other lens sharing the thread. The zoom is internal, so the barrel does not extend and the balance and overall length stay constant.
Autofocus and stabilisation
Autofocus is driven by a Stepping 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.
