Originally posted by TrueFocus Every lens can be improved, somehow. But from what I have seen around, the 18-35 will be just amazing. Especially combined with Pentax SR it just kills indoor event work. I cannot think of anything like it.
There's nothing like it, that's true.
But if you really want great indoor/low light work, then go Full Frame. A real pro camera (e.g. Nikon D4) will give you more than a full f-stop improvement over the top camera in Pentax's current line, as well as wider field of view. So a typical 24-70/2.8 lens on a pro body will give you a larger zoom range and similar exposure values. Using a fast prime on the Pro DSLR will outdo anything any Pentax is capable of.
OTOH, a Pentax K-5 ii (or ii s) + Sigma 18-35/1.8 will run less than half the cost of a Pro DSLR + 24-70/2.8.
You could buy two sets, plus two 70-200/2.8's (or similar) and be ready for weddings.