Grids are made up of cells that control off axis light in four directions while maintaining the soft quality inherent in a large light source. They allow you to create separation & depth such as a hair light where you want to control just the light going onto the hair in order to separate it from the background. As light is focused into a forward direction through use of a grid, it can help to eliminate spill light or lens flare.
The off axis portion of the light is controlled by the cell size. The cell size (measured in degrees) describes the maximum cutoff angle of the off axis light. A 40-degree grid is the most popular degree used.
Light loss at the center axis is minimal at a distance 3 to 4 times the diagonal dimension of the light source. On most models it is less than a 1/4 a stop of light. Grids are soft grids that collapse down for easy transport and travel. Each unit comes with an included nylon carry case.
Grids easily attach through the use of hook and loop tape. When attaching, place your diffusion panel about 1/2 way in on the hook tape. This will leave enough room for the egg crate to attach directly in front of the diffusion panel. Grid corners are left unattached in order to provide the perfect fit. This allows you to stretch the grid taut and avoid sagging or drooping.