How does a teleprompter work?

A teleprompter is the modern version of “smoke and mirrors.”

There was this theatrical method called “Pepper’s Ghost” in the 1860’s that used a stretched piece of thin fabric placed between the audience and the stage. It was invisible unless light was reflected onto it. The actors on the stage would do their thing until the phantom was needed to “appear.” Meanwhile, the actor playing the phantom would be in a darkened orchestra pit, below the main stage.

When light was projected on the phantom, their image would be reflected in the fabric above, causing it to be “on stage” with the actors. The two worlds would interact, and at some point, the phantom would be “extinguished” and the day was saved. The same idea is still used in modern stage presentations with Musion and also Disneyland’s Haunted Mansion.

So, how does a teleprompter work?

I profiled the presidential teleprompter in an earlier post. A traditional camera mounted teleprompter —or autocue— allows the speaker to look at the camera like normal. However, their script is now superimposed over the lens. This way it appears to the audience that the actor is making direct eye contact with them while still speaking from the heart. Teleprompter software takes a normal script file (in a format like .docx, .pages, or .rtf) and converts it into large letters on a contrasting background, typically, white letters on black.

This signal is sent from a laptop, tablet, or even phones, through a cable to the teleprompter monitor. Transmission can be via Bluetooth as well, but for mission critical shoots, I suggest staying with hardwired systems. The pandemic  created the need to send signal via Zoom, Meet, and Webex, too. So we came up with solutions for remote teleprompting.

Teleprompter monitors normally range from 7″ to 20″ with some gigantic 55″ exceptions. People on budgets also prompt on their iPads or phones.  When you look into a mirror, things are flipped. So, the signal into a teleprompter monitor needs to be flipped too. This can be accomplished either by your teleprompter software, or by special monitors that scan reverse the image. The Decimator MD-HX can flip HDMI and SDI signals. 

Because the special teleprompter glass is nearly transparent, the camera sits behind the mirror. The words then appear to float in space so that the speaker can look into the camera and read them. A teleprompter operator feathers the speed of the script to match the pace of the speaker. If the speaker slows or stops, the operator will follow.

The prompter operator also interacts with the camera crew and sets up the teleprompter equipment so everything is connected to the tripod and balanced correctly. Plus, an operator edits the script and often wordsmiths the lines. Phrases that look good on paper don’t always sound great when spoken aloud.

Typically, the speaker will start by rehearsing on paper, then advance to the teleprompter, make any edits, and only then will they hit the record button.

Some teleprompter apps can operate without an operator by using a preset speed, but it can be unnerving to the speaker to follow a machine. For example, the number “$23,577” takes up a small amount of space on the screen, and would go by quickly on a preset speed, but to speak out loud “twenty-three thousand five hundred and seventy seven dollars” takes a lot longer. Any sync would be destroyed and your speaker would be frustrated.

With a nod to everything going AI, there’s also a voice-activated prompting app which is great for solo speakers on a budget… doing everything themselves. It’s also GREAT for doing rehearsals. For live shows and professional grade videos, we still recommend a professional teleprompter operator who makes edits on the fly, who listens to your requests, and makes and valuable formatting suggestions.

For more of a teleprompter definition and some other great images, here’s the Wikipedia article.