Last Updated 60 minutes ago
Filmmaking Dictionary: Number 4 / 4Bank / Four-Bank
Definition
A four-bank, often written 4Bank, is a lighting fixture arranged around four linear lamps. On film sets, the term is strongly associated with Kino Flo’s traditional fluorescent fixtures, including common two-foot and four-foot versions.
The name identifies the lamp arrangement, not a fixed wattage, colour temperature or physical length. Specify the fixture model and size when ordering or calling for one.
How the Fixture Works
A traditional fluorescent four-bank combines lamps, a reflector or housing, a mounting system and compatible control electronics. The separate ballast and cable arrangement are part of the system, so the lamps and controls must match the manufacturer’s requirements.
The elongated emitting area can provide a broad source for faces, small interiors or reflective surfaces. Its softness at the subject still depends on the apparent source size, distance and any additional diffusion.
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Controlling the Light
Depending on the model, switching individual lamps or groups can reduce output. Doing so also changes the active emitting area, which can alter reflections or the character of the source. Moving the light, adding diffusion and controlling spill are separate ways to shape the result.
For example, an interview setup may use a four-foot four-bank through diffusion to create a soft key. If the fixture is visible in glasses, reducing the number of illuminated tubes may change the reflected pattern without solving the angle problem. Placement should be assessed alongside output.
Lamp and Setting Compatibility
Use the correct lamp type and length with the intended ballast setting. A control labelled for two-foot or four-foot lamps is not simply a generic brightness switch; incorrect combinations can affect colour and operation. Follow the specific fixture manual.
LED replacement tubes and modern linear-light systems are not automatically interchangeable with a fluorescent four-bank’s original electronics. Confirm the approved configuration rather than relying on the tubes fitting into the housing.
Production Checks
- Confirm lamp length, type and colour balance.
- Inspect connectors, lamp holders and mounting hardware.
- Check the intended ballast or control setting.
- Test flicker at the actual frame rate and shutter time.
- Assess spill, reflections and source size from the camera position.
- Transport and handle lamps using the appropriate protective equipment and cases.
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Frequently Asked Questions
Does four-bank mean four feet long?
No. Four refers to the number of lamps; length is a separate specification.
Is every four-bank dimmable?
No. Control options depend on the fixture and its electronics.
Related Terms
Browse all terms starting with 4 or return to the filmmaking dictionary.