Independent rotating system in front lens group. Macro to max. At full aperture and stopped down very good sharpness and brilliance. Flare not likely. Play in barrel.
Sharpness is good to very good at full aperture and stopped down.
Brilliance is good to very good but at 28mm less good in the corners. Suitable for higher demands. At 28mm and open aperture light flare at the edges. At longer distances and stopped down light flare. At 28mm very light barrel shape.