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Old May 18, 2006, 8:55 PM   #1
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There have been numerous links regarding information on filters (specifically polarizing filters)...I can't seem to find one link that had quite a large amount of information on the subject. I've seen it passed around these forums a few times but after searching for half an hour, I can't seem to find it.

Reason I ask is my girlfriend got me a circular polarizer for my birthday and I'm looking to read up on how to use it most effectively.
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Old May 18, 2006, 8:56 PM   #2
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And now I found how to look back on previous topics I've made...I've found it. http://dpfwiw.com/filters.htm
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Old May 19, 2006, 1:30 PM   #3
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I'm at a complete loss as to how polarizing filters work.

I have a Tiffen 58mm Circular Polarizer filter...there isn't a marking on the filter of where the blocking axis is. I took a couple test shots and the filter seems to reduce contrast and saturation; I was under the impression it was to do the opposite?

The image on the left is with the filter on; the image to the right is without the polarizer filter. Is this the effect that polarizing filters are meant to give or am I using it improperly?
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Old May 19, 2006, 2:49 PM   #4
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No it's not the affect - the picture on the left looks underexposed. What settings did you have the camera on? Was it on manual or another mode?

A CP will cause light reduction of a stop or so but since the camera meters through the lens it should adjust for this - unless of course you have the camera in manual in which case it can't adjust.
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Old May 19, 2006, 2:51 PM   #5
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By the way - you can hold the filter in front of your eye and turn it - you'll see the same affect as the camera will - as you turn it you should see the sky deepen and the clouds start to stand out.
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Old May 19, 2006, 2:53 PM   #6
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I had it set in Aperture-priority mode.

The shot with the polarizer filter was shot at 1/200 while the shot without it was shot at 1/400sec.

The camera should have compensated; should I have overexposed the shot with the polarizer?
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Old May 19, 2006, 2:57 PM   #7
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You shouldn't have to set EC just because you're using a CP - the 1/400 to 1/200 diff is the 1 stop I would expect the camera to make. I don't recall ever setting an EC JUST because I was using a CP.

Does it consistantly do this? if so, then I'm totally stumped.
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Old May 19, 2006, 3:29 PM   #8
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I just got it yesterday as a gift - I'm going to go out today and take some more pictures with it for further testing.
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Old May 19, 2006, 5:34 PM   #9
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Alright I just got back from testing the polarizer some more...the first shot is without the circular polarizer (just a UV filter):



Now below are two different shots with the polarizer filter:



Is this the effect that the polarizer filter is supposed to give? It seems to me that the images with the polarizer aren't any more saturated, but rather have less contrast and seem "dull".

Can anyone help me out here?
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Old May 20, 2006, 6:46 AM   #10
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It's hard to tell, but it looks like the sun was directly behind you, in which case the polarizer will have little effect. They have their maximum effect at 90 degrees from the sun and decrease in effect as you pan toward or away from the sun.
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