Front-end developer and tech writer · View profile
· 15 min read
The WCAG ratio is (L1 + 0.05) ÷ (L2 + 0.05), and L is relative luminance, not brightness. Green carries 71.52% of it and blue 7.22%, which is why pure blue on white passes at 8.59:1 while mid grey fails at 3.95:1. Here is the whole computation, run end to end.
· 11 min read
Crop factor is a ratio of sensor diagonals. It changes framing, not the lens — proved by computing field of view both ways — and it applies to the f-number as well as the focal length, which is the half most articles leave out.
· 13 min read
Four variables set depth of field, and subject distance dominates the other three. The exact formulas, a computed table, why the circle of confusion is a decision rather than a measurement, and what "full frame has less depth of field" really means.
· 12 min read
A stop is a factor of two in light. The f-number scale is powers of √2 for a reason you can derive in one line, EV = log2(N²/t) puts a number on it, and the three controls are equivalent in brightness only — never in the picture.