Turn the focus ring and watch the depth of field move through the scene. Snell's law · ray tracing · f/1.8 to f/16
Guide · 0/4
Make only the cup sharp.
Bring focus close and open the aperture (small f).
Thin-lens model, 0.03 mm circle of confusion (36 × 24 mm sensor). Rays cross a BK7 glass biconvex lens (n = 1.5168).
Visual mode: HDRI lighting, ambient occlusion, bloom, depth of field and quality that adapts to your device. Light mode: no post-processing, for phones, weak laptops and for studying the technique.
To focus closer, the lens moves away from the sensor. That is what the focus ring does.
1/f = 1/s + 1/vAn out-of-focus point becomes a circle on the sensor. While it is under 0.03 mm (36 × 24 mm sensor), it looks sharp.
H = f²/(N·c) + fEach ray is computed entering and leaving BK7 glass with the vector form of Snell’s law; rays are not hand-drawn.
n1·sin θ1 = n2·sin θ2In Visual mode the viewfinder is a 3D scene. Each pixel reads its depth and is blurred by its own circle of confusion, with the same formula as the page numbers, over a 64-sample disc.
c = f² / (N(s − f)) · |d − s| / dSharpness limits are verified in tests by a second method (image-side geometry), within 2%.