Orientation of CP filter?

cloudphreak · 06-12-2010, 01:10 PM

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) ?

ytterbium · 06-12-2010, 01:51 PM

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.

**blackcloudbrew** · 06-12-2010, 02:09 PM

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.

cloudphreak · 06-12-2010, 02:26 PM

Great, thanks for clearing that up.

Ira · 06-12-2010, 03:05 PM

Originally posted by blackcloudbrew

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?

Wheatfield · 06-12-2010, 06:53 PM

Originally posted by Ira

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 90º

adwb · 06-13-2010, 09:42 AM

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

cloudphreak · 06-13-2010, 10:50 AM

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.

Ira · 06-13-2010, 10:55 AM

Originally posted by Wheatfield

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 90º

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.

ytterbium · 06-13-2010, 12:11 PM

Originally posted by cloudphreak

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.

Wheatfield · 06-13-2010, 07:34 PM

Originally posted by ytterbium

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.

06-12-2010, 01:10 PM	#1
cloudphreak Junior Member Join Date: May 2010 Location: Ashburn, VA Photos: Albums Posts: 30	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) ?

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06-12-2010, 01:51 PM	#2
ytterbium Veteran Member Join Date: Jan 2008 Posts: 1,076	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
blackcloudbrew Loyal Site Supporter Join Date: Mar 2009 Location: Cotati, California USA Photos: Gallery \| Albums Posts: 4,460	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
cloudphreak Junior Member Join Date: May 2010 Location: Ashburn, VA Photos: Albums Posts: 30 Original Poster	Great, thanks for clearing that up.

06-12-2010, 03:05 PM	#5
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by blackcloudbrew 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
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by Ira 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 90º

06-13-2010, 09:42 AM	#7
adwb Veteran Member Join Date: Sep 2009 Location: Bristol UK Photos: Gallery Posts: 1,636	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
cloudphreak Junior Member Join Date: May 2010 Location: Ashburn, VA Photos: Albums Posts: 30 Original Poster	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
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by Wheatfield 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 90º 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
ytterbium Veteran Member Join Date: Jan 2008 Posts: 1,076	Originally posted by cloudphreak 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
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,981	Originally posted by ytterbium 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.