Any device that generates and shapes light — spotlights, softboxes, LED panels. The tool between power and subject.
Light fixture
The light fixture is your direct tool between the power generator and the subject. It shapes light — not just quantitatively, but qualitatively. A 2.5 kW HMI spotlight and a softbox of the same wattage produce completely different visual results. The light fixture determines the hardness, color temperature, beam angle, and controllability of the light. On set, you need a clear distinction between the light fixture itself (hardware) and the lighting effect it produces — this often gets blurred in communication with assistants and the gaffer.
Practically, you differentiate by construction type and application. Fresnel spotlights — your classic workhorses with adjustable focus — allow for quick on-the-fly adjustments. HMI or Tungsten versions give you continuous light with a defined color temperature. Par cans are robust, simple, and efficient for long distances. Softboxes, octaboxes, strip lights — these are shaping modifiers that you mount on base fixtures (mostly Tungsten or LED) to diffuse the light quality. LED panels have radically simplified set handling over the last decade: low heat generation, dimmable, color-controllable, but often with less optical control than traditional spotlights. Your choice depends on the shooting location, power availability, temperature management, and above all, the desired light control.
On set, you need to know: Every light fixture has a focusing behavior. A focusable Fresnel creates hard edges that you can break up with diffusion or softboxes — this is active light control. A bare Par can is uncontrollably scattered; with lenses or flags, you force it into shape. LED panels emit a broad spread — ideal for even illumination, less so for dramatic shadows. Remember: the light fixture is only as good as your ability to position and flag it. A 1.2 kW Fresnel in the wrong position with a poor shadow edge is worthless. A small LED panel placed correctly, with a honeycomb grid and diffusion, can carry the scene.
The light fixture is also your budget indicator. Your gaffer will quickly tell you whether you need an 18 or 40 kW generator — that costs money. And every light fixture takes up physical space in the truck, requires assistants, cables, and mounts. On a low-budget set, you're often forced to light a complex scene with three or four fixtures. On a high-budget set, you'll splurge on five HMIs, four softboxes, six LED panels — because time on set is more expensive than the light fixture itself. Understanding this trade-off makes you a good lighting designer.