Yes, it will vignette with one thick filter.  If you want to put a
filter on get a slim one.

I just got a hood, EW-83E, for Christmas, I can report back later.

Greg

Forgetting the vignetting, while one filter may not cause any noticable
issues, two is pushing it.  Take the UV off when you want to use the
polariser.  Simple.

I been using mine without.  Works good.

$I have the Rebel XT and want to get back the wide angle I lost going
$digital. I was planning on buying the Canon 10 - 22. I was going to buy a UV
$filter for general lens protection and I also need a polarizing filter. Can
$I stack the 2 or will it vignette?

  I would be very surprised if it didn't vignette.  Stacking filters
on even a wide-angle zoom usually causes vignetting, and one would
expect the same on an ultrawide.

  If you're going to be using a polarizer, you should take off the
protection filter first.

  You know, of course, you'll probably stir up the usual hornet's nest
of debate as to whether or not you should even use a protective filter
in the first place ...

$                                   Also - can I get away without a lens
$hood?

  The hood for this lens doesn't provide a great deal of coverage;
that's unavoidable on an ultrawide lens, as an effective hood for a
lens with such a wide field of view would have to be enormous.  Still,
it's better than nothing, and while you *can* get away without it,
you'd be best off to get it if you can.

------------------------------------------------------------------
    Say hi to my cat -- http://www.stevedunn.ca/photos/toby/

Two will definitely vignette - a standard Hoya UV creeps into view at
12mm. As others have commented, the polariser will need to be a
low-profile mount to have any chance of avoiding vignetting at the
widest angles.

You can, but I wouldn't recommend it. Unless the sun is directly
behind you the vast FoV of the 10-22mm is going to pick up some stray
light. After experimenting I now always use the hood.

Beware your feet in the bottom of portrait-format images! <g>

Al