Learning Photography Course — 6. Lighting

Module 6 of the Learning Photography Course. Everything that happens to light before it reaches the camera — which is the half you can actually change.

Light arriving at a subject has four properties and every lighting decision anybody makes is one of them: intensity, direction, colour and quality. 'Quality' has a bad name, because it sounds like a judgement and it is in fact pure geometry — and this module states in one sentence exactly what controls it.

The sun is 1.4 million kilometres across and is, photographically, a SMALL light. NASA's own Sun Fact Sheet puts its apparent diameter from Earth at 1,919 arcseconds on average — about half a degree — and that half a degree is why a midday shadow has an edge you could cut yourself on. Put a cloud layer over it and the source becomes the whole dome of the sky: the largest softbox ever built. Golden hour is a change in the light, not a dimming of it, and the module separates the three things that change at once.

Then: why moving a light closer softens it (the box did not change, its angular size did), what direction does to apparent shape, and colour temperature — including why low kelvin values are the ones we call warm, which is the exact opposite of the emotional language and is not going to change.

Speedlights as a capacitor discharging through xenon rather than a bright lamp, and everything that follows from that. Guide number as a definition rather than a measurement. Sync, and the banded frame — which is not a fault but a photograph of a moving slit, taken by a light too quick for it. High-speed sync, and the two or three stops it costs. First and second curtain, and the difference between a car that appears to be reversing and one that is moving.

The inverse-square law, derived in one diagram, with the part people get wrong: falloff is violent close in and gentle far away, which is why a light placed close darkens the background for free and a light placed far away evens everything out. Distance decides falloff, and falloff is the one thing you cannot fix afterwards.

Every studio modifier in existence does one of exactly two things — change the apparent size of the source, or restrict where the light goes. The module says so once and the catalogue becomes a list of instances.

And the assembly: one light first, then fill and the ratio between them, then rim, then background — and balancing flash against daylight, where the shutter controls the ambient and does nothing at all to the flash.

No guide number, sync speed or flash duration is quoted for any named product, because each belongs to one unit on one day rather than to a technology.

Educational documentary. Not financial or investment advice.