UV and polar filters

[r.morales]

Should I stack them ? Which goes first ?
I saw a difference when I used both on my old AE-1 , but today I took 4 shots with my new XTI in bright sun and other than the size of flower [ different zooms - same lens ]
1. with polar 1st UV 2nd
2 . UV 1st polar 2nd
3 . UV
4 . polar
These are dumb questions but I want to know .

[SkipD]

NEVER stack filters unless it is has to be done to accomplish something special (like using more than one neutral-density filter because one isn't enough). You would be risking increased flare from all the extra glass surfaces.

[Grentz]

it may have not come out in that situation...but down the road it could pop up at the least appropriate time.

[r.morales]

So , If I don't see a difference - should I just stick to UV?

[SkipD]

A polarizing filter can do what no other filter type or any software can. Properly positioned (they all rotate in their mounts), a polarizing filter can reduce or even eliminate reflections on non-metallic surfaces such as the surfaces of water, glass, auto paint, etc. In the case of reflections on windows and water, you can see what's behind the reflection when using a polarizing filter.

Polarizing filters can also help to darken a blue sky against the clouds and land-based objects and they can help to emphasize the color of foilage (by eliminating reflections off the leaf surfaces).

For modern cameras with autofocus systems, the "circular" polarizer is highly preferable over "linear" polarizers. Both are round, so the difference is not immediately obvious.

[r.morales]

Thank you for explaining polarizing - no refection and better greens and bluer . I think the one I have is linear , is there a way to check easily ?

[Jon]

Doesn't say "Cir." on it somewhere?

Got a pair of polarizing sunglasses? Rotate it in front of them - if things go completely black at some point it's linear.

[SkipD]

I think the one I have is linear , is there a way to check easily ?The easiest way to be absolutely sure that a polarizer is circular vs. linear is to hold the filter up between you and a mirror. You want to be holding the filter so that, in the mirror, it covers the eye that you'd be using to look through the filter. Thus, you are looking through the filter twice to see your eye in the mirror. Then flip-flop the filter so you are looking at the other side of it.

If you have a linear polarizer, you will be able to see your eye in the mirror with the filter held both ways.

If it's a circular polarizer, you will see it blacked out in one direction and in the other direction you'll be able to see your eye in the mirror.

[r.morales]

Thank you , it's circular , quess I lucked out when I bought it .
I have both , the EFS 18-55 and the EF 28-90 . Is there better choice for standard - IE which one should have polarizing ? After reading other comments I have a UV on both .

[Jon]

Whichever one you're using when you need it. Seriously, polarizing filters aren't something you just leave on all the time. They're only really useful at cutting glare, reflections or haze but at the expense of two stops of light. IIRC both your lenses take 8 mm, so use it on whichever lens you're using when it will help. I've got one for each of my lenses but that's because I use multiple bodies and I don't like changing filters when I change lenses.