Practical Light

What this is about

Practicals belong to two departments at once, which is why they get argued about early. Production design buys the lamp for how it looks; the electrics department then opens it, swaps the bulb for a controllable one and runs it through a dimmer channel so the DP can set an exact level. On a night interior the practicals often carry the whole atmosphere, and the film units hidden outside merely bring faces up to a usable exposure.

A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.

What runs differently here

Where this differs from the general case:

• Practicals are almost always dimmed; at full output a bulb in frame clips long before the room is properly exposed.
• Bulb choice sets color temperature in shot, so it has to match the film's palette rather than the shop's stock.
• Rewiring, dimmer channels and cable runs to a practical take time and belong in the setup estimate, not in the gaps.

With TillyGen

TillyGen lists practicals with both the props and the lighting notes of a setup, so nobody discovers on the day that the lamp has no dimmer.

Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.