The best compromise of all Affordable

The kit lens SAL-1855 is in drawing and CA (Chromatic aberrations, cyan red and magenta-yellow color fringing) along with a very below average drawing the Useless. The SAL-1680 Zeiss has qualities in the naturalness of the colors but otherwise other issues that one would have to discuss separately. The Sigma 18-50 is optically more than disappointing, "shines" with distinctive rainbow colors in the form of CAs, particularly in the periphery and at any dimming. In addition, there are dull as an old trousers, strongly increasing from the center to the edges.

So now this Tamron AF 17-50 2.8 (continuously). It's big and heavy but solid processed and comes with sun visor. Zoom and distance is set pleasantly on beautiful wide rings. Filter thread does not rotate! In telephoto mode the trunk travels acceptable from not too far. In 17 of the Zoom mechanically ge-locked can be. The Obejektiv has built not shake protection. One need not even when the sensor of the camera, it already does (Sony Alpha 35) but I'm already not a fan of this tremor protection especially when the Zoom will not be a Tele. The electronics are also usually quite power hungry. If you have photographed life, you know how and when to hold a camera steady.

The optical property of Tamron AF 17-50 are all excellent in comparison to the above. A "fragrant" drawing on all focal lengths and even at full aperture already; So sharp in detail. This glass has the narrowest and lowest CAs in the edge areas of all so far. (Lenses over 1000 are here, of course, not taken into account). The colors are maximally natural and there is no color cast over anything that would compensate the white balance. The barrel distortion at 17mm seems to be very low, at least mine did not fall on none at all, even at the edges of buildings. The much-lamented noise of the AF drive is totally irrelevant if you do not constantly zooms through infinity from 20cm to. This is probably also often on weak Konrast detections many cameras that can find no sharpness level even with multiple Zooming. Subsequent corrections in the current shooting range expire so quickly and quietly that you feel no disturbance in the practical application.
The intensity of the tube is a quality in itself, especially since they may remain constant over the entire zoom range. And it's really not a problem and no restriction itself to work with 2.8. On the other hand, the automatic of the various cameras is rarely choose the maximum aperture. One would there already normally intervene with manual adjustment.

So, although the 16-80 Zeiss has more.Zoom reserves and significantly more than twice as expensive I would not exchange it for this "cheap" very prime Tamron.