[LouD]

I'm trying to figure out whether there is any point to waiting for the new Sigma 17 50 or buying the 18 50 now. They claim their version of shake reduction on the new lens is good for four stops more or less.
I have a k-x. Have seen some suggestions that its shake reduction isn't all that effective, at least not compared to high-end Pentax gear.
The new lens will be replacing a 24 70 2.8 that the Sigma folks were kind enough to trade me for my old 24 60, which they could not repair under warranty. The 24 70 is a wonderful lens, but way too heavy (two pounds) for my tired old wrists. Thus I do not have a walking around lens and I'd like to get one before the summer is over.
I am committed to Sigma, I live about 15 min. away from their Long Island repair center, and can have my lenses calibrated to the kx on the same day.

[Russell-Evans]

I'm trying to figure out whether there is any point to waiting for the new Sigma 17 50 or buying the 18 50 now.

I haven't seen the Sigma 18-50mm f2.8 macro for sale for a while so I would think your only option is the new Sigma 17-50mm f2.8 OS? The current price I see for the 17-50mm f2.8 is close to $700, and way out of my budget, so I would probably be looking at the Tamron 17-50mm f2.8. The Tarmon is a smaller, lighter lens than any of the Sigma lenses so you might like it even better for your wrists.

Thank you
Russell