I often shoot with a death lense but I have never turned off the image stabilizer. All shots are handheld. Is it true that I should turn it off? Will the image stabilizer make the picture better or will it degrade my image quality?

Also...should I turn off the image stabilizer in the event i shoot with a tripod? thanks

Nah, it doesn't make any difference in the video quality, no matter what lens you have on the camera, it can only help out, if you get any vignette, with the stabilization on, you'll see the vignette moving around, because of the OIS, but other then that, it can only help.

When the camera is on a tripod, you should turn off the OIS, because when you pan or tilt, it will think that is camera shake and try to componsate for it.

Luke,
Unlike electronic image stabilizing systems, optical image stabilizers will not degrade your image. They work on different principles.

But you probably don't need stabilization with such a wide-angle adapter on your lens. The wider the shot the less the need to stabilize the image.

If your shooting form a skateboard I would keep it on to help smooth out bumps and cracks in the surface you are skating on. I'd also leave the lens on manual focus as with a fisheye your depth of field is almost infinite.

thanks all...your help is appreciated as always!