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06-12-2010, 01:10 PM   #1
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Orientation of CP filter?

Is there a "proper" orientation for a circular polarizing filter? I have two Hoya CPs, both have a white hash mark on the edge. What does this mark indicate? I notice in the viewfinder that the image changes slightly as I rotate the filter through 360 degrees, but is there a correct position for the filter for normal landscape shots (and by normal I mean the sky is at the top of the image) ?

06-12-2010, 01:51 PM   #2
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No. You adjust the filter for the best effect.
Light from different objects will come polarized at various angles. Depending on what you want to filter out, you rotate the filter and visually check if the reflection disappears.

The only thing to observe is the front orientation of filter. It works only one way. So if your'e using some sort of exotic reverising/sepping ring setup, be sure that the true front of filter always point to scene.
06-12-2010, 02:09 PM   #3
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The technique I've used for years is to find the sun then turn 90 degrees from it and focus on the sky. Rotate the polarizer until the image is darkest. Then you have it set.
06-12-2010, 02:26 PM   #4
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Great, thanks for clearing that up.

06-12-2010, 03:05 PM   #5
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QuoteOriginally posted by blackcloudbrew Quote
The technique I've used for years is to find the sun then turn 90 degrees from it and focus on the sky. Rotate the polarizer until the image is darkest. Then you have it set.
Is this true regardless of the direction you're shooting in relation to the sun?
06-12-2010, 06:53 PM   #6
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QuoteOriginally posted by Ira Quote
Is this true regardless of the direction you're shooting in relation to the sun?
Not as. But, when one does this with a WA lens, the sky will show significant brightening as the angle off the light goes off 90
06-13-2010, 09:42 AM   #7
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cloudphreak,
always look at the shadows, if you are 90 degrees to them the poloroid filter work at it's best,
as you turn toward [or away] from the sun the effect decreases till you are head on or have your back to the sun at which point it does nothing for you.
remember the shadows thats all.
Alistair
06-13-2010, 10:50 AM   #8
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Thanks Alistair. I'll try to keep the sun at 90 deg, or take the filter off if that's not possible. I'll wait for a sunny day and take some test shots.

06-13-2010, 10:55 AM   #9
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QuoteOriginally posted by Wheatfield Quote
Not as. But, when one does this with a WA lens, the sky will show significant brightening as the angle off the light goes off 90
I'm using a cheap Cokin type CP now, although I have 2 brand-new 55 Hoyas (long story). Problem is fitting all of my lenses so I don't have to buy so
many filters, AND also being able to use the hoods.

This is why I keep getting pulled back to the Cokin system.
06-13-2010, 12:11 PM   #10
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QuoteOriginally posted by cloudphreak Quote
Thanks Alistair. I'll try to keep the sun at 90 deg, or take the filter off if that's not possible. I'll wait for a sunny day and take some test shots.
That's only true if you're after darker sky and more cloud contrast. Polarizer can have many enchanting effects besides that - e.g. increase foliage saturation.
06-13-2010, 07:34 PM   #11
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QuoteOriginally posted by ytterbium Quote
That's only true if you're after darker sky and more cloud contrast. Polarizer can have many enchanting effects besides that - e.g. increase foliage saturation.
Any effect a polarizer has is from reducing polarized light. What is happening when it increases saturation is that it is reducing reflections off the surface of the object.
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