Indoor shoot — studio or built set. Marked INT. in call sheets. Controlled. Light is your only variable.
You need an interior space for your scene — be it a living room, office, or hotel corridor. As soon as the camera has four walls around it, you're working with an interior. The advantage is obvious: controllability. You decide what goes in and out. No unexpected clouds, no cars driving by in the background. But it's precisely this control that becomes your problem, because you must use it perfectly.
In the call sheet, you note every interior scene with INT., followed by the room and time of day — INT. KITCHEN - DAY. This signals to your team: everything must be built or decorated. The Production Designer needs to know if you're using a real location or have to build one. The Gaffer is already calculating when reading the plan how much light they'll bring into this box. Because that's the central challenge: lighting in an interior is your full responsibility. You can't dim the sun, you have to replace it.
Practically, this means recce and floor plan sketches. How high are the ceilings? Where are the windows located? How much wall space do you have for hanging silks or for reflectors? Lighting a 4x4 meter room with a south-facing window at midday is a different task than a dark attic. With a studio interior, you have ceiling openings and limitless power; when shooting on location, your lights work against the existing architecture. You consider whether to bring light from above (through the ceiling) or from the side, whether to work with HMIs or with tungsten in cinema standard. A living room style is lit differently than a factory hall — finding motivated light is your core task here.
Interiors also demand camera discipline. You can't just move around everywhere. Ceiling is ceiling, wall is wall. This forces you into framing rather than spatial escape. Shallow focus, depth through lens choice and movement — these become more relevant than outdoors, where the landscape has already given you a sense of depth. And in editing: interiors allow you to plan eyeline matches and shot-body-shot sequences stringently. Every look is a conscious decision, not given randomly by the space.