Originally posted by bdery Why didn't you buy the kit lens with your camera? It would have been cheaper.
There are three versions of that lens. Version 1 is pretty good. Version II (labeled as such) is even better. Version 3 is weatherproof and has the same optics as version II. That might explain the differences.
But if you're going to purchase a lens like this, but not as a kit, there are better lenses that could be purchased for just a little more money, such as the Pentax 16-45 (if you can find it), the 17-70, or the Sigma 17-70.
To muddy the waters even further, there's also the DA-L lens varient as well. It has the same optical formula as the II and WR versions but has a plastic lens mount to save weight. It also does not include the Quick Shift focus system found on other DA lenses.
These can typically be found very cheap, and the trade-offs are minimal in the grand scheme of things.