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Thread: "Default" position of CPL lens?

  1. #1
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    "Default" position of CPL lens?

    What is the default position for a cpl lens?

    Lets have hoya's lens as example. It has the small white "arrow" on it, where it should point by default?

  2. #2
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    There is no default positon for a circular polarizing filter. I had to check my hoya filter to see what you were talking about, I think you're referring to the small white triangle on the rim? I think that is intended as a reference point to gauge rotation, but I don't think it is very useful: Note that the triangle is on the moving part of the filter, but there are no corresponding reference points on the threaded (stationary) portion. None of my other polarizing filters (B+H and Breakthrough) have a similar mark. Just don't worry about any "default" position and look through the lens while rotating to see the difference. Adjust the amount of polarization in this way to suit your tastes.

    Stephen

  3. #3
    Senior Member conropl's Avatar
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    My filter does not have marks, but wish it did. A polarizer has a series of parallel lines in/on the glass. If the lines are running horizontally, then light that reflects up towards the lens is reduced (I will spare you the details of why). Around water, I want to reduce the glare off rocks and the water which is mostly light reflecting up... so I would want the polarizer lines horizontal. If I had a vertical surface with reflections (glare), then vertical lines would be better. I am not sure for the "blue sky" effect (the light is polarized), it would depend on your placement relative to the sun (but it is most effective if the sun is 90 degrees to you, and then I would assume vertical lines or 45 degree lines would be best... not sure though).

    I guess what I am saying is, it would be nice to know for a starting point and to make sure I did not move it, but in the end you need to adjust it for the best effect relative to the angled surface anyway. So adjusting for each set up is required... so maybe there is no real point or time savings to knowing the orientation of the polerizer lines.

    The other area I would like to know the orientation is for flash photography. If you put a polarizer on your lens in one orientation, and then put a polarizer film on the flash at 90 degrees relative to the lens polarizer; then you get a really neat effect that gets ride of all the glare. Great for macro photography. It is nice to know the orientation of the lines, but in the end all you have to do is look at your flash polarizer through the lens, rotate the lens polarizer until your flash polarizer turns black, and you then know they are at 90 degrees to each other (then mount the flash in the same orientation).

    Pat
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  4. #4
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    I was so hoping there is the default point =) oh well, that's why it rotates, to find the needed view per situation.

  5. #5
    Senior Member neuroanatomist's Avatar
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    Quote Originally Posted by Karsaa View Post
    I was so hoping there is the default point =)
    There can be a default point as soon as the sun stays in the same place in the sky and you decide to take all your pictures facing the same direction.

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