Out of control iris control!
 

The cute little iris wheel on my PD150 has gone haywire. Each time I make an adjustment, it the aperture size skips and jumps all over the place. I eventually manage to land on the desired value, put it tends to make for a quite frustrating ordeal.

I suspect the the wheel mechanism to be busted, but maybe there's some hidden aperture feature on the cam that I've overlooked? Any thoughts?

It does sound faulty. There are no hidden controls that I know of assuming you have the camera in full-manual operation.

It has been so long since I had my camera in anything but full-manual mode, I don't remember what happens if all of the adjustable settings aren't in manual.

You can do the push button trick to bypass the exposure wheel entirely Eivind. Move the chrome slider to the central position and push the 'shutter speed' button at the back. Select 1/50th (or 1.60th if you're NTSC). Leave the camera in the auto exposure mode but point the camera to give the exposure you want and push the 'exposure' button alongside the wheel.

This will lock down the exposure which is GOOD. Should you want to adjust the exposure, push the button again till you get what you want and push the button to lock that in. It's a bit like the 'push auto' focus facility. You use the automation to determine the setting, and push the button to stop it wandering off at a tangent.

tom.