Unfortunately, though only in plastic, but since little is moved, it has hitherto been a disadvantage.
The professional may criticize the aperture (in addition to other aspects of durability), but the amateur photographer, it would be to get as great Bouqets.
Unfortunately, too few of these type of lenses, one wonders why need to work all the digital SLRs with lenses so bad (from 3.5 etc.). In the upper class there are few comparable lenses that then but the price the acquisition value of the camera good times around 3-fold excess (EOS 450D)