a7x, a9 PDAF stripe noise technical analysis

Started 9 months ago | Discussions thread
Horshack Veteran Member • Posts: 6,744
Visualizing how a single light source is directional

My grasp of light and refraction physics is tenuous but here are ray diagrams I drew to illustrate how a single like source like a flash in the center of the frame creates directional light at each pixel, which in turn is determines which PDAF rows/pixels will manifest striping based on their specific mask geometry. The original Sony patent describes multiple mask geometries to handle various focal lengths, each which has different exit-pupil distances and thus accepts/delivers from different light ray angles.

I hope I got these diagrams right

Each diagram shows a point of light emanating from the same flash exposure, and where that point focuses on the sensor. As you move away from the center of the flash (radially but illustrated vertically for simplicity), some of the peripheral rays from flash land outside the FOV, so a larger percentage of light rays are converging from the opposite direction. For example, the red ray diagram depicts how most of the light converges from "above" the pixel, whereas the green diagram depicts the opposite.

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