You may not want that model anyway. In the Canon universe, the newer version with built-in IS is considered inferior optically.
I've owned the original model for both Pentax and EOS mount for the past few years. It's a real bargain. Not perfect, but plenty good enough for my work purposes. There has been a long line of complaints on all platforms about inaccurate focusing. A moderate focus adjustment (after diagnostic testing) on my K20D fixed the problem permanently. I've had no issues with my 7D.
This is one of the sharper tools in the box. The build quality isn't great (3.5/5) but I think that's just due to plastic being the interface to the touch, including a cheesy lens hood. The lens itself is not superlight however.
My only issue with this lens is the rendering of certain colors: greens, blues, violets. They're a little "off" from my Pentax ideals. Fixable with a Lightroom preset or two. Interestingly on my Canon, the colors are just fine. I have this unfounded theory that Tamron used Canon and Nikon bodies to determine acceptable reference colors for rendering (for obvious reasons) and that's that.
The reality is that the Pentax platform excels in primes; the available zooms are mostly average with a couple of exceptions. So the Tamron is your best bet for this range. Another suggestion would be the DA 16-45mm; well-proven, but f4. Sigma makes an 18(?)-50mm f2.8, but I'm ignorant about it. I prefer my zooms in a popular range to be f2.8.
M
Originally posted by Ubuntu_user But this version you're talking about isn't available in Pentax mount, is it? Will it ever be?