The Development of a Fixed Polarizing Filter

Brokenland wrote:

it's been nearly one year since making this discovery. This all started when I was searching for a polarization filter/CPl for my Canon M6. I've test dozens of already manufactured filters and none of these worked in conjunction with my camera and I'll not go into any details about this, I've already heard it all and most of it has been negative towards me or my discovery.

I've got plenty of experience with polarizers (including publishing Programmable Liquid Crystal Apertures and Filters for Photographic Lenses at Electronic Imaging in January 2021) and I haven't got a clue what you are trying to claim here. What do you mean by "Fixed" and in what way are you saying polarizers failed on your M6?

Polarizers (even electrically twistable LC ones) can be either linear or circular. Linear ones have the light leaving them linearly polarized, while circular ones add a quarter wave plate to convert that into circular polarization. BTW, the quick way to check if a polarizer is linear or circular is that circular ones don't show the usual polarization effects if you look through the front of them with the filter back facing the scene. Linear vs. circular matters primarily when using a camera that has a beamsplitter in it -- which DSLRs generally use to get light to the PDAF sensor -- because how much light a beamsplitter diverts changes with the polarization angle of linearly-polarized light hitting it. Thus, modern polarizers are usually circular, but ones from before cameras did autofocus are often linear; my experiments found linear ones were generally ok on masked-pixel PD mirrorless cameras (e.g., Sonys), but I didn't test dual-pixel PD Canons like your M6.

As for the "fixed" aspect, are you talking about physical rotation? Just to be clear, linear vs. circular has nothing to do with physical shape of the filter nor with whether the polarizer mounting can be rotated. Polarizing filters made for photographic use often have a rotating mount so that the linear polarization of the incoming light that you want to pass can be adjusted to block polarized reflections off glass or other such surfaces, but the natural polarization angle for sky is pretty constant, so a linear or circular polarizer doesn't need to rotate if your primary goal is to increase contrast of skies. The catch on that is ultrawide lenses capture light at angles that change significantly across the frame, making front-mounted polarizers give somewhat uneven results across the frame; usually, this effect isn't obvious until wider than about 20mm FF field of view.