[hcc]

Correct. Camera image stabilisation (IS) and lense optical stabilisation (OS) are not compatible. You switch off one or the other.

While the debate is still open on the performances of IS versus OS, arecent article and a few threads suggested that there is not much in between. SLRgear.com conducted a systematic test with the Olympus E520 on IS versus OS, and it is very informative:
Image Stabilization Test: Olympus E-520 SLR Body - SLRgear.com!

For Pentax users with IS camera, this simply means that we have more choice of cheaper, non-OS lenses than the Canikon people.

[aliquis]

Pardon my ignorance, I did not know you could have both lens stabilization along with sensor stabilization. Wouldn't they impede one another? Or is the effect cumulative, as in, if you were to get 1 extra stop out of the sensor IS and 1 extra stop out of the lens IS, you would get 2 extra stops with the combination? That would be amazing with the K-x's high ISO capabilities.

You will turn either off, in this case the in camera I assume with the benefits in the viewfinder in mind.

[Parallax]

Pardon my ignorance, I did not know you could have both lens stabilization along with sensor stabilization. Wouldn't they impede one another? ...........

Yes, they do work against each other. Actually I'm not sure whether they work against each other, (i.e. results worse than with neither) or if they just cancel each other out, but Lens based IS and Body based IS do not play well together. Turn one or the other on, but not both.

[glanglois]

Pardon my ignorance, I did not know you could have both lens stabilization along with sensor stabilization. Wouldn't they impede one another? Or is the effect cumulative, as in, if you were to get 1 extra stop out of the sensor IS and 1 extra stop out of the lens IS, you would get 2 extra stops with the combination? That would be amazing with the K-x's high ISO capabilities.

Working together, if possible at all, would require close development ties between Sigma and Pentax. We've seen no sign of the right business relationship, never mind possible technical avenues.

And while we're at it, I shot family photos tonight with my new 18-250mm Sigma OS. Rather dim light indoors. My old Tamron 18-250 wasn't fast enough for those same rooms and frequently struggled to focus.

Sigma on K-X found focus quickly (with and without assist from Metz 58 AF) and LCD reviews looked fine. Looking good so far!