Cameras and Lenses – Bartosz Ciechanowski

Abstraction: Interactive first-principles explainer of camera sensors, lenses, and optics

Key points:

• Pinhole camera inverts the image (rays cross at the aperture); smaller hole sharpens the image but reduces light and eventually reintroduces blur via diffraction
• Bayer filter uses two green channels (1 red, 2 green, 1 blue per 2x2 grid) because green correlates with perceived luminance; demosaicing reconstructs full color by interpolation
• Convex lens derived from stacking prism segments: converges parallel rays to the focal point; thin lens equation relates object distance, image distance, and focal length
• f-number = focal length / entrance pupil diameter; halving aperture area doubles f-number ("one stop") and halves light per pixel
• Depth of field decreases with larger aperture diameter and shorter focal length; out-of-focus highlights form a "circle of confusion" whose shape matches the aperture iris (polygonal bokeh)
• Aberrations covered: spherical aberration (fixable with aspheric lenses), chromatic aberration from dispersion (correctable with achromatic doublets), plus coma, astigmatism, field curvature, and distortion

Connections: Bartosz Ciechanowski · Optics · Photography · Lens Design

Source: https://ciechanow.ski/cameras-and-lenses/