The barrel is made of plastic with the mounts being metallic. The construction feels sturdy and is quite lightweight. This will be particularly appreciated by trekkers and mountain hikers who avoid taking a long zoom lens to the hills just because of its heavy weight.
The lens barrel features knobs for autofocus and vibration compensation (optical image stabilization). There’s also a lock knob for locking focus which also prevents zoom creep.
The large zoom ring occupies most of the barrel, and is perfectly placed with a ribbed rubberized surface. The zooming action has good tactile feel to it, and one can feel a distinct resistance after the 70mm mark.
The focus ring is right in front and naturally within the reach of the fingers, and offers a smooth action, though I also felt it’s a bit too smooth for precise manual focusing. I’d personally have liked it to have a bit more resistance, like the zoom ring.
One issue with the zoom lock button is that it locks zoom only at the minimum, i.e., 18mm point. So, if you’re taking a long exposure photo on a tripod with the lens pointing up or down, at anything other extreme wide-angle, or extreme telephoto, the lens tends to collapse or extend under its own weight. And the zoom lock is pretty much useless in this scenario. This may not be a concern for all, but can definitely cause irritation to some photographers.
Apart from this minor flaw, overall the lens is perfect in terms of design and construction with all controls being very accessibly placed.