The first impression of the lens is very positive, it feels high-quality, the adjustment rings run clean and free of play, not hooked or scratched, the zoom ring is only between 28 and 35 mm a little sluggish, the focus ring is running wonderfully soft, the "decoupled" sense of focus, due to the quick shift mechanism I feel not as a nuisance that can be objectively and focus manually quickly and safely. By internal focusing, the front lens does not move, which facilitates the use of circular polarizing filter-for whose operation is also a removable window in the tulip-shaped lens hood. This is stable, coated on the inside and fitted with a bayonet, so they simply turned around to transport can put on the lens.
Since I already had experience with high-zoom, the weight and dimensions for me were now not particularly surprising, they are comparable to previous 28-70ern with early Aperture 2.8, 50 mm lens is by far extended tube rather long, what with studies at short distances (because of the low minimum focusing distance of 30 cm, the lens can also be used before as fast macro) sometimes a bit annoying.
Fully extended, the two-stage moving out front tube minimal lateral play, I have no comparison objective, therefore, so can not say whether only my copy has this peculiarity, but an influence on the image quality I could not tell.
The AF reacts at the K5 quickly and quietly, a defocus I could see so far at any focal length, the focus has always been spot-on.
The sharpness is very good overall at maximum aperture at 16mm is here but a visible edge drop (at least in my test setup) detected, the already largely disappears at f 4, in Aperture 5.6 - 8, the lens is consistently above all Brenweiten to the brim sharp. From aperture 16 to 22, the imaging performance takes to my mind again somewhat. The lens is available in Aperture range 4 -11 over all focal lengths with no restrictions, in my opinion it has the best performance in the range of aperture 5.6 and 8. The 16 mm fall at my copy at full aperture somewhat, in photographic everyday this was for me to now, however, disturbing at any time. The contrast is consistently at a high level, also here the Objekitv is weakest at 16mm with full aperture. The lens has a pleasant color display that allows in conjunction with the K5 in daylight fantastic pictures. The Schärfeverlauf is also very good, objects may be exempted wonderful in front of a blurred background at full aperture, you have to be able to reach into the feeling, in this looking at the pictures.
With a 16 mm for this short focal length rather light, at least not me very disturbing barrel distortion is noticeable. At 50 mm my copy recorded minimal cushion-shaped, this distortion does not fall under normal use to but was only visible when the corresponding test setup.
At 16 mm a slight but overall uncritical vignetting is detectable completely disappear from 24 mm.
With mounted lens hood I had until now no major problems with stray light. Fringing on edges counterpoint occur in my copy in a total of not excessively recognizable degree, but are in some motifs especially at the edges of metallic objects at higher magnification but recognizable.
The price will naturally first violent, compared to the prices of equivalent original objectives of the other major manufacturers this into perspective, however, again.
The somewhat weak 16 mm and the minimum lateral clearance of the tube are so far my one and only criticism of this otherwise excellent lens.
