# Thread: Need help on how to rotate circular polarizer

1. ## Need help on how to rotate circular polarizer

I know there are some threads on CPL already but I couldn't find the answer that I need.

So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.

2. ## Re: Need help on how to rotate circular polarizer

Originally Posted by sci80899
I know there are some threads on CPL already but I couldn't find the answer that I need.

So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
Simple. Just rotate till the pointer faces the sun.

But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).

3. ## Re: Need help on how to rotate circular polarizer

Originally Posted by daredevil123
Simple. Just rotate till the pointer faces the sun.

But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).
very true, can't find any better technical way to answer ts question, other than rotate you like what you see in your VF

4. ## Re: Need help on how to rotate circular polarizer

Originally Posted by sci80899
I know there are some threads on CPL already but I couldn't find the answer that I need.

So to use a polarizer, there an arrow mark on the rotating part if my CPL. Am I right to say that I should rotate it such that the arrow mark is perpendicular to the light source, so if outdoors would be where the Sun is

Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
There is NO technical answers as it all depend on the angle of your view vs the angle of the light.

5. ## Re: Need help on how to rotate circular polarizer

Originally Posted by daredevil123
Simple. Just rotate till the pointer faces the sun.

But it is better to do it the way you have been reading (i.e. rotate till you like what you see in your VF).
Thanks daredevil123, have a happy lunar new year.

6. ## Re: Need help on how to rotate circular polarizer

Originally Posted by sci80899
Most online answers just mentioned rotate until you like what you see but I'm looking for a more technical answer. Hope someone can advise. Thanks much.
For the technical answer first you would need to know the orientation of the light rays that you want to keep. This can change, depending on whether you want to enhance a blue sky or remove reflections on a window. Keep it simple, use the method that you got from your reading

7. ## Re: Need help on how to rotate circular polarizer

No offense to anyone ...

For polarization to take place, both the light rays and polarizing film have to be at certain angles.

However, it might be much easier to simply look through the viewfinder and rotate the pol filter till you get the effect you need. If you do want to be more technical, a photographic polarizing filter works best in the 30 - 56 degree range.

For more details, Google 'how a polarizer filter works' but be prepared for a lot of physics and maths.

8. ## Re: Need help on how to rotate circular polarizer

Thanks guys. Happy CNY.

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