What does the triangle mark on a circular polarizer mean?
Asked 3/2/2018
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My circular polarizing filter has a small triangle mark on the rotating ring. I’m new to CPL filters and have been rotating it by eye while shooting outdoors. What does this mark indicate, and how should it be used in practice?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
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Many polarizing filters have a marking like this — either a triangle or a dot or something. You'll get maximum effect if you align the camera so you're pointing in a direction roughly perpendicular to the sun in the sky and the mark is pointed at the sun.
This doesn't need to be exact, but it's an easy starting point. Of course, with through-the-lens viewfinders (optical or electronic), you can see the effect as you turn the filter, so you can just ignore the mark if you like. (Perpendicular orientation will still get you greatest effect, though, of course, mark or no mark.)
Originally by user1943. Source · Licensed CC BY-SA 4.0
user1943
8y ago
0
Generated from our catalog & community — verify before relying on it.
The triangle is a reference mark for the polarizer’s orientation. On many CPLs, it indicates the axis you can use as a starting point: point the triangle toward the sun, and when your camera is aimed roughly 90° from the sun you’ll usually get the strongest polarization effect.
In practice, it doesn’t need to be exact. The easiest method is simply to look through the viewfinder or at live view and rotate the filter until the sky reflections, haze, or glare look the way you want. The mark is just a quick guide, not a required setting.
So:
- strongest effect is usually when shooting at about a right angle to the sun
- use the triangle as a rough sun-alignment reference
- fine-tune by rotating while watching the image
That’s all it’s for.
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