Lighting
Lighting language, and why it is the highest-leverage thing to specify
Key, fill, rim, practical, motivated, raking. A short vocabulary that changes output more than any style keyword.
01
Three lights, and what each is for
Key: the main source. It decides where shadows fall and how hard they are. A large soft key close to the subject gives gentle gradients; a small hard key far away gives sharp-edged shadows.
Fill: a softer source on the opposite side that controls how dark the shadow side goes. No fill means a genuinely dark shadow side, which is what most "cinematic" reference actually is.
Rim or backlight: behind the subject, catching an edge. It separates the subject from the background. It is also the only way to make steam, breath, dust, rain or hair read on camera.
02
Ask for the shadow side
The most useful sentence you can add to a portrait or interior prompt is a description of what the shadow side does. "One side of the face lit, the other falling into deep shadow with only a faint edge of detail" produces an entirely different image from the same prompt without it.
Flat, even, frontal light is what most generated video defaults to, and it is the main reason output looks televisual rather than filmic.
03
Motivated light
Motivated means every light in the frame has a visible source: a window, a lamp, a screen, a doorway, headlights. Unmotivated light — a subject lit brightly in a dark room with no visible reason — is the tell that something is generated.
Naming the source also fixes the colour and direction for free. "Lit only by a laptop screen" implies cool, low, frontal and soft, without you specifying any of it.
04
Raking light for texture
Light striking a surface at a very shallow angle makes every micro-variation cast its own shadow. It is how you make fabric look woven, wood look grained, skin look real and metal look machined.
If a prompt is about material quality — and most product and craft prompts are — raking light is the single specification that delivers it.
05
Time of day does a lot of work
"Golden hour", "blue hour", "overcast midday", "night with sodium streetlights" each carry a complete package of direction, hardness, colour and contrast. Naming the hour is often more efficient than describing the setup.
Be aware of what each implies. Golden hour means low, warm and backlit with long shadows. Overcast means soft, directionless and low contrast. Asking for golden hour and hard shadows on both sides of the face is asking for something that cannot exist.
