Last Updated 5 days ago
Filmmaking Dictionary: Letter G / Grid Cloth
Definition
Grid cloth is a family of reinforced diffusion materials used to spread light in film and television production. It is commonly supplied as a roll, a framed piece or a sewn rag for a larger frame. Different weights scatter different amounts of light and have different transmission characteristics.
The grid in the name refers to the material’s construction. It is not an eggcrate or honeycomb grid, which restricts light spread. Grid cloth diffuses; an eggcrate helps control the spread from a source.
Full, Light and Quarter Grades
Manufacturers use names such as full grid, light or half grid, and quarter grid. Compare products within the named range rather than treating those labels as universal optical measurements.
- Full grid: generally the stronger diffusion grade in a given range.
- Light or half grid: an intermediate option, depending on the manufacturer’s naming.
- Quarter grid: generally a lighter diffusion grade, with more of the original beam character remaining.
The result also depends on the fixture, its beam, how much cloth is illuminated and the distances involved.
Quarter Grid Cloth
Quarter grid cloth is a lighter grade of grid-cloth diffusion. It can take some edge off a source while retaining more output and direction than a heavier grade from the same range. “Quarter” does not mean a quarter-stop loss.
As a product-specific example, LEE 434 Quarter Grid Cloth lists 60% transmission under its stated measurement conditions, with loss described as less than three quarters of a stop. Another manufacturer’s quarter grid may behave differently.
A lighter cloth may leave a visible hot area or more direct light through the material. Check the subject’s shadows and the illuminated cloth rather than judging softness from the grade name alone.
Advertisement
Size, Distance and Softness
Diffusion does not automatically make any setup soft. The apparent size of the illuminated source from the subject matters. A large, evenly illuminated frame close to a face behaves differently from a small piece far away.
If a hard light illuminates only the centre of a large frame, the unlit edges do not contribute the same way as a fully lit surface. Adjust the source-to-frame distance and beam coverage, then check the actual shadow quality.
For example, a crew may switch from a heavier rag to quarter grid to retain more level. That changes diffusion as well as transmission, so it is not simply an exposure adjustment.
Quiet Versions, Handling and Rigging
Quiet grid-cloth products are intended to reduce rustling compared with standard versions, but their diffusion and transmission may differ too. They are not a guarantee of silent operation in wind.
Large rags and frames can catch wind and impose substantial forces on their supports. The key grip determines the rigging and weather limitations for the setup. Do not assume a stand’s vertical load rating describes the safety of a large outdoor frame.
Keep the cloth clean, identify its grade and follow the material’s heat-clearance and flame-rating requirements. Professional diffusion is not automatically flame-retardant; for example, LEE identifies several grid-cloth products as NFR.
See the key grip guide and diffusion entry for the surrounding workflow.
Grid cloth is one type of rag. Other rags are designed to bounce, reduce or block light, so specify the fabric and grade as well as the frame size.
Related Terms
- Diffusion
- Honeycomb Grid
- 4′ × 4′ Frame
- 6 × 6 Grip Frame
- Fractional Diffusion, Gel and Filter Strengths
Browse terms beginning with G or return to the filmmaking dictionary.