Where is the mark on the polarizer supposed to be?

Started 1 month ago | Questions thread
BBbuilder467 Veteran Member • Posts: 4,409
Re: Where is the mark on the polarizer supposed to be?

ThrillaMozilla wrote:

I didn't measure with lab equipment, but my Hoya filter seems to be right on the mark. It's easy to measure, so I assume that generally the marks are quite accurate.

I think it's possible that you are confused about the direction of polarization. It doesn't always "point to the sun". Reflected light is (partly or totally) polarized perpendicular to the plane of the incident and reflected rays.

For reflection from a surface, the direction of polarization is oriented relative to the surface, not to the sun. In the sky, polarization is at a maximum at a scattering angle of 90 degrees.

And just to make the explanation more complicated, on photo filters a straight line passing through the center and the mark is perpendicular to the plane of polarization, so the mark does indeed point to the sun for maximum effect. In scientific instruments the mark is generally rotated by 90 degrees relative to that in photo filters.

That was basically the logic. Rotate the pip mark toward the sun, rather than away from it. It wasn't meant to be precise, but it made a simple reference point.

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