Exposure · Matching cameras
Every slider click is one third of a stop. Three clicks = one stop = double or half the light.
Footcandles = light on the subject, read with an incident meter: fc = 25 × T² ÷ (ISO × t). At T2.8, ISO 800, 1/48 that is about 12 fc. A 0.3 ND = 1 stop.
Teaching model: T-stops and ISO are counted in true third stops (the engraved numbers are rounded); shutter time = angle ÷ 360 ÷ fps; ND 0.3 = 1 stop. The picture is exposed for a 12 fc key (correct at T2.8, ISO 800, 180° at 24 fps), with highlights clipping to white and higher ISO adding noise.