The lens solidly constructed with a low reflectivity black finish and a rubberized zoom control. It comes with a "petal" style detachable lenshood. The barrel material appears to be plastic.
The zoom can be locked in the 28mm position so that the lens doesn't extend when being carried in a downwards position.
Focus can be switched between AF and MF with a small switch on the left, near the lens mount. Manual focus is smooth and well damped with about a 51 degree rotation of the rubberized focus ring from 0.33m to infinity. There are no depth of field scales and no IR focus identification mark. It's marked with focal lengths of 28, 35, 50, 60 and 75mm
Focus speed is good. It takes the Tamron SP AF28-75/2.8 XR Di LD Aspherical (IF) Macro about 0.65 seconds to go from 0.33m to infinity (or infinity to 0.33m). Focusing isn't silent but it's pretty quiet and certainly not a problem.
The lens extends when zoomed (from around 92mm long at 28mm to around 129mm long at 75mm), but does not change length on focusing (it's internal focus - IF) and the front of the barrel does not rotate when the lens is zoomed or focused. However the focus ring does spin during autofocus, so keep your hands away from it.
More review here, thanks
http://www.bobatkins.com/photography/reviews/tamron_28_75.html
