Where is the mark on the polarizer supposed to be?

Started 2 months ago | Questions thread
lehill
lehill Veteran Member • Posts: 5,717
My Hoya CPL glass not locked in alignment
1

Dem Bell wrote:

As it happens, I had three random old Hoya polarizers in the draw, and I checked if the mark on the rim of these filters corresponds to the orientation in which the polarized light is blocked. No, it does not! It is all over the place! For two filters it was off by about 15-20 degrees, the third one was off by about 60 degrees. The actual position of the mark has nothing to do with the orientation of the polarizer grid and its maximum effect.

This begs the question: why bother putting a mark on the rim if it does not mean anything? Is this mark just a visual cue to tell you by how much the polarizer is being rotated? I am confused now. Should the tutorials be rewritten? Can my three filters be duds?

Three polarizing filters. The orientation that removes all polarized light (this is the orientation perpendicular to the direction of the polarizer grid) is marked by white putty (UHU White Tack). For all three filters, this is not the orientation marked on the filter.

I have that 62mm Hoya PL-CIR, it's my oldest CPL. Every once in awhile the front element will just pop out - there's just a very skinny spring clip holding the glass in place by friction. I've always just stuck the glass & clip back in without regard to the mark.

There's no physical index (eg, keyway) to align the glass and frame. So it's pretty easy to see how stuff can get out of alignment over time.

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Lance H

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