I've just upgraded to an XM2 after reading only good about it. The test shots were excellent until I shot in a white room with artificial light (4 x 60 w bulbs). Then I encountered serious "light fall off" (a term I've learnt from an able member of this site). The picture was horrific, it looked like there was a grey halo around it. I didn't notice it on the LCD, only when I dumped it to my Mac. I tested some more, found this forum and realised it happens to others too.
Someone suggested that the camera is so good otherwirse that it's best to avoid the situation. However, I live in the middle east.... the majority of walls are white and most events happen indoors in the summer because it's too hot outside! So I can't always avoid it.
I took the camera back yesterday with print outs of frames. They swapped it immediately.
The replacement is just the same... a bit worse actually as you can hear the tape transport on this one.
To make sure it wasn't just an odd situation, I took the same footage with my old Panasonic NV DA1. There was no light fall off atall.
I now have a choice... take it back today (last day for exchange) and get the new 3ccd Panasonic (the something or other 400 which has very good reviews) or find out from your good selves that I'm doing something very wrong!!
FYI, the shadows appeared in Auto, TV, AV and manual. I got rid of them by putting f-stop to 4, but the picture was way too dark.
Any help gratefully received!!

Have you tried white balancing and retesting? Adjusting and Setting the Presets? Mixed lighting can be a real pig.

Now I'm going to investigate this, on this forum and with my cameras too! - G

See this thread before you make a decision:
http://www.dvinfo.net/conf/showthread.php?t=3430&highlight=keyhole

I encountered and investigated this three years ago. What you describe turns out to be a characteristic of the lens at certain apertures. Nearly all lenses, particularly wide zooms, will vignette to some degree under certain conditions.

Thanks for the quick replies. I'd read the thread earler which is how I know it happens to others.

I can appreciate some lighting conditions might be difficult, but a normally lit room at night shouldn't reall be too much of a problem. I wish I could post a couple of stills so you can see how bad it is! And the old panasonic has no trouble with it.

I tried the auto white balance and the two presets. Same result.

I just tried it again (daylight). It's still there, but not so visible (my wife thinks I'm imagining it :).

I don't want to "downgrade" but I don't want an expensive camera that has this problem as 50% of video I take is indoors. I can't afford to step up to an XLS or similar.

Canon's on line help doesn't address the situation.