Circular or Linear polarizing filter for EOS40D and EF 28-135mm IS?

As a gift for my daughter (I don't know about these things) I want to
buy her a polarizing filter. But I am told there are two types. What
should I get for a EOS40D and EF 28-135mm IS?

 

You want a circular polarizing filter, not a linear one. Pay the extra for
a decent multi-coated one.

 

Circular - 72mm

 

a circular polarizer is required for any camera with a beam splitter.
autofocus slrs, including the canon 40d, have a semi-silvered mirror,
so therefore you need circular.

for a compact p&s camera or old manual focus slrs, you can use either
one.

 

Thanks to all who replied!

 

I agree. Even if your camera did not need a circular type,
your next camera might. A circular type works with all cameras.

 

I'm using B&W circular polarizer with the same lens,
but the added weight of the filter messes up with IS.
With IS on and filter in front, photos get blurry when
you zoom in (80-135mm). The focus is correct, but
it looks like motion blur... So, you should either
warn your daughter to turn IS off when using it, or
avoid buying her a gift that'll give her headache

 

that should have absolutely *no* effect on stabilization.

a polarizer is typically going to require a stop or two more exposure
and maybe you're shooting at a slow enough shutter speed where the
slower shutter speed becomes a problem. or maybe the filter is very
dirty.

 

Yes, it should not, but it does With 28-135 the entire
front element wiggles, and vibrates when IS is on. When
you mount a heavier filter (and B&W's sure aren't light)
it obviously loses a delicate balance which is essential
for it's proper function. And I have done several tests
which all came out blurry as hell, even with 1/2000s
or 1/4000s exposure. No problem with 28-80mm,
but the blur emphasizes with longer zoom extention.

Believe me, it's not the case. I've been shooting for 28
years now and there's no way I could make a mistake
like a newbie I used the polarizer on a bright sunny
day, and even if I needed to shoot at a slower shutter
speed (and I didn't), IS should compensate without a
problem.

 

So using a lens hood or lens-protecting filter (such as UV) on your
zoom should reduce the quality of your IS images, and if you use both
the effect should be worse. Since that's much more common than the use
of polarising filters, who has noticed that?

It doesn't affect my images, but that may be because my camera uses
in-camera rather than in-lens image stabilisation.

 

Just a very poorly designed (or faulty) lens.

David

 

i've never seen a stabilized lens where the front element wiggles.

 

Mine doesn't.

Are you an engineer?

Your problems with a particular lens cannot be used to generalize.

And yet ...