For a zoom it has a first-class color reproduction, resolution and contrast. Even the bokeh and sharpness, I find very appealing.
It is a innenfokussierendes lens and even the focus ring does not move with the AF. The Quickshift is therefore very pleasant and useful works without switching from AF> MF on the lens or body.
The focus ring can turn on (it is decoupled out of the focusable range, but you can tell by the slight jerk), which is more like a gimmick, but MMN. can be seen quite positive.
The feel I find very appealing. It is very good / processed with value and stable, so that nothing wobbles, or much play!
When zooming the lens slightly extended (in the right direction: the more BW, the longer) and the 2-piece tube emerges.
On the camera, it can be easy to operate, with handle, it is however pleasant.
With 77mm diameter filter for this are unfortunately quite expensive. A slim version is MMN even at 16mm. not necessary.
A few disadvantages there are also:
The zoom ring is not as smooth as the Da * 50-135, it is properly connected resistance behind. Nevertheless Smoothly zoom can be, so I was no star deduction.
Visually it is necessary to make a few prints, I would still describe it as full aperture suitable.
At maximum aperture, it tilts at the beginning of the focal length range to (moderate) and edge blur at the end to (moderate) CAs. Stopping down can both prevent relatively well. Nevertheless, I am quite satisfied with the results at maximum aperture. Since this is a zoom lens and to be reckoned with drawbacks: no rating trigger.
The initial teething problems have now been resolved. Back then SDM failures and incorrect focus was often decentrations reports. This is now hardly the case.
Since the beginning of 2012 a new SDM engine in the 16-50 and 50-135 will be installed, which should be significantly more reliable now. Since then reads barely defective motors in these two lenses.
Therefore, I would recommend this lens rather than the 17-70 Because that continue to suffer losses. Alternatively, is the 16-45 As I have previously owned, not bad suitable if it does not depend on weather resistance and light intensity.
The Da * series is better sealed than the WR lenses.
But should not be confused with weather resistance Waterproof! Each lens has to regulate by an air exchange when focusing / zooming printing.
By the seals while splashing is held and the likelihood of damage to the pictures in the rain is significantly reduced compared to unsealed lenses, a guarantee can be given, however, do not!
In most cases, it can, however, use without problems when it rains. Most of the moisture is held for the rest of the camera belongs properly dried (in a bag + silicate bag).
Therefore water always wipe immediately, never sprayed with pressure (shower, etc.) and when it is wet as little as possible to focus / zoom.
It is perfectly normal even when sealed lenses which to fog in high humidity + heat (eg in the tropical house) inside. The dissolved air in the water vapor can not keep up and comes through zooming etc. in the lens. After a few times zooming in normal air, the water vapor should be but disappeared.
Conclusion:
Despite the small drawbacks I can recommend the lens with a clear conscience and give it 5 stars.
Who wants better quality needs to resort to fixed focal length lenses.