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Old Jul 26, 2006, 12:21 AM   #1
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I'm having problem understanding how to use a Circular Polarizing filter? Can someone with experience with these filters explain how? At what point you need to stop turning the filter?:?

Also, can you set it once and leave it and that setting will work for all situations? Front of the lens does not rotate but would zooming make any difference???:?
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Old Jul 26, 2006, 2:00 AM   #2
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It depends on what you're using it for. For getting rid of glare from water or window reflections, you stop turning when the glare is gone or at minimum. If you are using the CP just to darken your exposure, then you stop turning when you like what you see.

CP's are mostly used for getting rid of glare reflections, so you might have to adjust it whenever the angle of light changes.

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Old Jul 26, 2006, 4:12 AM   #3
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Just look through the viewfinder, turn the thing and see what changes. You will notice the biggest difference when looking at reflected light such as glare coming off of a water surface. At one angle you will just see the glare. At full polarisation the glare will disappear and you will be able to see stuff under the water.
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Old Jul 26, 2006, 4:51 AM   #4
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Glare on water, in windows etc. but not reflections on steel or polished surfaces
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Old Jul 26, 2006, 6:29 AM   #5
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Also does a good job removing haze (from reflected sunlight) in landscape shots. Unless you actually need a circular polarizer, a linear polarizer will work just as well and costs a lot less.
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Old Jul 26, 2006, 10:08 AM   #6
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The problem with that, as I understand it, is almost all DSLRs cannot focus with linear polarizers.
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Old Jul 26, 2006, 3:17 PM   #7
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You don't mention what camera you are using. You can usually see the effect of the polarizer very well with a DSLR. Just rotate the polarizer until you get the best effect – either removing reflections or darkening the sky.

With an EVF it becomes problematic and with a LCD even more difficult to make fine adjustments and see exactly what you are getting. You are often using a polarizer in sunlight and the LCD is quite hard to see well enough to make the kind of adjustments you want. With an EVF an eyecup helps a lot, but it still isn't completely satisfactory IMO.

I wear polarized sunglasses. They are all polarized the same way to block reflections. Generally if you have your sunglasses perfectly level you have the same polarization set that you would with the mark on the camera polarizer straight up. I just tilt my head until the sunglasses give me the best effect and set the mark on the polarizer the same way.

LCDs have a polarizing layer. Many years ago almost all LCDs were impossible to see wearing polarized sunglasses as they were polarized the opposite of the sunglasses. So I couldn't tune my car radio or see my watch without removing the glasses. It is rare anymore to find LCDs polarized that way. I can see all of my cameras fine in both orientations – the polarization is at an angle.

Reflections from water are usually best blocked with the mark straight up. Much sky polarization is such that you get the sky the darkest with the polarizer near the vertical. But at some times of the day and in some directions that isn't true. You have to tilt the polarizer as far as 45 degrees to get a dark blue sky. It is best to have some way of adjusting the polarizer. If you have a DSLR it isn't a problem at all.

Zooming makes no difference as long as the lens doesn't rotate.

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Old Jul 27, 2006, 4:50 PM   #8
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Thank you for the answers as they are lifting the fog for me...

I am using Canon 30D camera. My problem is that it is hard to see the difference very clearly in the viewfinder (it is small and not very bright), and it is even harder to see it in the LCD after taking the picture.

Are there any tricks or rules of thumb to judge when to stop turning the polarizing filterto achieve the best results?
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Old Jul 27, 2006, 6:21 PM   #9
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Take the filter off and hold it up close to your eye. You can get an idea what you are looking for and what rotation you are using. You will find you never go more than 45 degrees from having the mark straight up for sky polarization and usually have it about straight up for reflections from water etc.
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