It was a good companion for a long time with a very good image quality, a relatively fast autofocus and a very effective image stabilization. I was very pleased with it, which meant that the new had to be only better simply ...
And that's the Sigma!
The focusing means of ultrasonic motor is faster and more accurate than the Tamron taken what was not already bad. The positive side effect from HSM is the silence. The focus is sitting even with darker lighting conditions indoors where other lenses, and the Tamron, work no longer as accurate or "pumps".
The quality is excellent. There nothing wobbles and bweglichen parts have no game. The zoom ring has a great resistance, the exact adjustment of the focal length possible. While the Tamron was easier, which was OK, but had a little game. It was not as accurate.
The focus ring of the sigmoid colon can be operated exemplary. While the Tamron the game way too big (tapping decided between sharp and blurred), also the rotational path was quite short, it is the Sigma as it should be.
The most important, the image quality, can be described with one word: sauscharf!
That does not sound like excessive euphoria, but the Sigma 17-70 contemporary is one of the sharpest lenses, with whom I have worked. The Tamron has often been praised for its good image quality, but it does not come close to the Sigma.
The longer focal length is more important to me, has become as a continuous Lichtstaerke of 2.8. The minimum focusing distance, which is well below that of the Tamron, the smaller body proportions, the lower weight, the relatively low price and the properties described above, all result in a great overall package, which I made the decision easy.
A lens with a high fun factor!
PS: My subjective judgment is based on pure observation and direct comparison without
Laboratory Equipment)
