So, I assume you've bought a DSLR and now you are disappointed by the 18-55 kit lens that comes with your camera.
This is mostly true speaking of Canon kit lens, but anyway Nikkor kit lens, though being a much better lens, may be not what you were looking for, in terms of quality.
So, it's time to upgrade to a better lens that has near the same focal range.
Well, there are many options: if you decided for Canon, you may take a look at the 17-40 F/4 L, while if you have chosen Nikon you could be interested in a VR lens. But it will cost you a lot, you're advised.
So, where can you find good quality for little price? Here's where Tamron 17-50 F/2,8 comes into play.
Let's take a look at this product.
Firstly, the focal range is almost the same: you lose something in the tele-range, but you earn an equivalent mm on wide. That's not much, in fact it isn't the biggest value with this lens.
The most important advantage this lens gives you is a constant 2,8 aperture within the whole focal range. This is a great improvement compared to the kit lens.
The 2,8 max aperture grants you a very soft bokeh, useful speaking of portraits.
The minimum focus distance is 0,28 m, so you can use this lens for macro too. Just don't pretend them to be as stunning as the ones you can obtain from a real macro lens ;-)
The image quality is very good, and from F/5,6 on, exspecially in the center, it is incredibly sharp. Some tests state it to surpass a 8 megapixel CMOS (like the one used on Eso 350D) resolution.
Border quality, however, tends to decay a little, exspecially below 25 equivalent mm, but you have not to worry about that as any wide lens shows a similar result (even the Canon 16-35 F/2,8 L, which costs over 1500$).
The AF isn't lightning fast, but it's not a matter not being this a telephoto lens. It's also a little noisy, but nothing to worry about.
Speaking about the body, the lens looks enoughly solid. It'not magnesium alloy nor metal, but the feeling is positive.
There's one, HUGE, problem with this lens. You see, Tamron, Sigma, Tokina and eany other third-part constructors don't guarantee a quality control comparable to Canon, Nikkor and so on. That means that you could purchase a great lens, but there are also chances you could end up with a flawed one. It was my case. Mine had a HORRIBLE, and i mean HORRIBLE, image quality decay in the right border. It was so bad it looked like an out of focus shot, the image was so blurred it looked like a bokeh, and I'm not exagerating at all. The whole right corner looked AWFUL. So, keep it in mind, this could happen to you, too (although I think flawed lenses are about 10% of the lot).
However, if you get the good one, you'll have come up with a great lens.
I suggest you to take a look to the Sigma 18-50 F/2,8 HSM too, that's pretty much the same lens but with some improvements. Although I've never tried this one, it should be capable of better macro shots (shorter minimum AF distance) and, above all, it mounts a HSM af motor, really silent and fast.
Let's come to the price. Here, in Italy, Tamron 17-50 costs about 400 €, that is 300 dollars more or less.
Wide aperture (though veeeery soft)
Sharpness from F/5,6 on
You may end up with a flawed model if you're unlucky
A little focus hunting with wider apertures
I rate this lens with a 7,5 out of 10 (and a full 8 considering the price).
Thank you for reading, goodbye.
(Here's an example photo)