Originally posted by D1N0 The 24-70
Looks about the same size as the Pentax D FA 24-70. No great loss when it doesn't come in K-mount. Same goes for the 100-400. 5-6.3 We have a 150-450 4.5-5.6 though the Sigma is a lot more compact with a 67mm diameter instead of 86. And probably also cheaper and lighter.
The Global Vision lenses are swappable from mount to mount. Which could be handy if you have a nice copy and are switching systems.. get to keep your Sigma lenses. Well.. as long as you don't switch to Pentax. Then you're hosed.
The 24-70 will matter in how it performs at 2.8 and throughout in the edges and corners. And, of course, price. Plus it works with the dock so we have 16 AF adjustment points (4 focal lengths at 4 distances) versus the 1 Pentax gives us in body.
But we don't have that.. because we chose Pentax. And guys here say who needs AF? Manual focus is the way to go.