What are those things called that news crews use to diffuse the sun's light on a subject? They are big cloth-looking rectangles on stands that diffuse the sunlight. Are they simply diffusers, or something else? Thanks.
Genericly such devices are known as "overhead sets" and come in various sizes from 4x4' to 20x20' and even larger ones constructed by the grips from speedrail pipe and hung from construction cranes, or mounted between buildings.
The frames are "skinned" either with various grades of silk, thicknesses of nets or even solid black to control the sun for photographic purposes of creating a specific atmospheric look or for matching weather conditions of another days' shoot. The most common usage is to "take the curse" off of the direct sunlight look which comes with a typical sunny day at highnoon.
In addition, various reflective materials can also be mounted on the frames including grifflin cloth, muslin or shinny metalized material sometimes known as "microwave" because of the intense amount of light (heat) it puts out. The frames are in this case positioned to reflect the sunlight and act as a large source of illumination.
Use of these frames requires some skill and concern for safety as they can easily be carried away, or down upon unsuspecting actors or others (crew) by sudden bursts of wind; for they are nothing more than sails put to another purpose.
Professional grips secure overhead sets with strong stands, heavy sandbags and rope tied to sturdy trees, buildings, cars/trucks and stakes pounded into the ground. To do so safely presumes some knowledge of knots and their uses, and even to transport and assemble these units often takes large trucks and crews; just to move a 12x12 or larger frameset takes at least four people and a large footprint once its built-up.