trombone

Etymology

Borrowed from Italian trombone, from tromba (“trumpet”) + -one (augmentative), literally “large trumpet”. The telecommunications sense alludes to the shape of the musical instrument.

noun

1. A musical instrument in the brass family, having a cylindrical bore, and usually a sliding tube (but sometimes piston valves, and rarely both). Most often refers to the tenor trombone, which is the most common type of trombone and has a fundamental tone of B♭ˌ (contra B♭).
   Jim plays the trombone very well.
   This trombone is very expensive.
2. The common European bittern.
3. (film, television) A kind of extendable support for attaching lighting elements to a set.
   The trombone […] permits an instrument to be positioned over a studio set wall, enabling the set wall to support the weight of the instrument. 1983, Alan Wurtzel, Television Production, page 131
   The two secondary controls are the trombone handle and the focus knob. 2013, Harry Box, Set Lighting Technician's Handbook, page 480

verb

1. (telecommunications) To transmit a signal or data back to a central switching point before sending it out to its destination.
2. (film, slang, transitive) To extend and retract (the zoom lens); to use it too enthusiastically.
   […] do things wrong (like rotating the lens turret while shooting or backwinding and doing multiple passes on the same strip of film or doing in-camera fades with the variable shutter or tromboning a zoom lens like a teenager on acid, etc., etc., etc.) […] 2015, Kathryn Ramey, Experimental Filmmaking: Break the Machine, page 357
   He recalls (email to editor, 2 December 2012) that Durgnat 'shouted out' in response to his 'tromboning' the zoom-lens at the film's 1967 London Film Festival screening: […] 2014, Henry K. Miller, The Essential Raymond Durgnat, page 71