Grips use different size frames to cover, reflect or diffuse light and many grip companies still refer to these as "Butterfly Frames"...But why are they called butterfly frames?
In the early days of filming, the Grips would hold a post that was connected to a giant circle frame with many different nets to tone down the light. These frames resembled butterfly catchers so they became known as Butterfly Frames.
Here is a picture showing a butterfly frame in use...
Grips no longer use the round frames on film sets today.
Here's a picture showing many different size frames working on a set.
The frames are made by many manufacturers with lots of rag choices for overheads, bounces or backdrops.
Here's a list of the most popular rags.
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