a7x, a9 PDAF stripe noise technical analysis, part deux

Started 8 months ago | Discussions thread
iso rivolta Contributing Member • Posts: 550
Re: test reflection hypothesis with linearly polarized light?

Antisthenes wrote:

Note that with cameras that have an optical low-pass filter, the OLPF's quarter-wave plate sitting between the OLPF's two birefringent crystal layers will convert light into circularly polarized light. Any linear polarization that you apply to the light source will therefore be destroyed by the time the light reaches the sensor's surface.

Thank you for the reminder on OPLF. I believe that the A7R that Horshack uses is not having such a filter. Even if it has a similar arrangement with Nikon's D800E there would be no quarter-wave plate.

The problem is that there are many other surfaces in front of the metal grid and all these surfaces reflect better the s-polarized light and transmit better the p-polarized light, therefore variable amounts of light are reaching the photosites depending on the orientation of the linear polarizer.

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