Symbol 5055 from IEC 60417 - Title/Meaning: Focus Function/description: To identify the focusing control(s), for example, of a television receiver, a monitor, an oscilloscope, an electronic microscope.
Additional information: 
Published in: First edition, 1973
Own work using: iso.org/obp/graphics/grs/1c64aa1a-2b57-4b66-bb38-96071ff78938 200.png
Vectorization:  Mrmw