Teleprompter

Overview

A teleprompter (or autocue) is the invisible performer's friend in broadcast and studio production. Instead of memorizing scripts or holding a cue card in frame, talent reads from a prompter mounted directly in front of the camera lens. The key to invisible cueing is optical: a 45° angled glass plate reflects the script text onto the talent's eyes while transmitting the camera's view straight through to the lens. From the camera's perspective, the glass is nearly invisible; the talent sees bright, scrollable text at eye level.

The high-brightness LCD sits beneath the beam splitter inside a hooded cage. A collimating lens above the monitor projects the text image upward and outward onto the angled glass, which reflects it toward the camera lens. The operator uses a wireless remote to scroll through the script in sync with talent delivery, adjust font size and color, and control which camera is "live" (for multi-camera setups).

Optical path

Light from the LCD screen passes through a collimating lens (approximately 75 mm focal length), which transforms the diverging light from the display into a nearly parallel beam. This collimated light travels upward toward the angled glass plate. The plate's optical coating is a partial mirror: it reflects roughly 50% of the light (the script) back toward the talent's face, while the other 50% is transmitted through to reach the camera lens. From the camera's perspective, looking straight at the glass, the reflected script light creates a faint ghost image (minimized by the glass thinness and angle), but modern high-brightness displays and careful coating minimize visible artifacts.

The talent, standing just behind the camera, sees the reflected script text at eye level and reads it naturally. The motorized focus mechanism allows fine adjustment of the collimation to account for the talent's distance from the glass and the camera lens position. Too close and the text blurs; too far and it's dim. A rotary encoder on the operator's remote provides precise control.

Control and software

The operator runs dedicated script control software on a laptop or tablet, feeding the script into the system. As talent delivers lines, the operator scrolls with a scroll wheel on the wireless remote, keeping the visible portion of the script synchronized with speech. The software supports:

• Font size and typeface selection (crucial for reading at a distance)
• Text color, background color, and transparency adjustment (some talent prefers dark text on light, others the reverse)
• Line spacing and margin adjustment
• Multiple script languages side-by-side for bilingual production
• Camera designation (in multi-camera setups, only the "active" camera's glass is bright; the others remain dark to avoid distraction)

The wireless remote communicates via 2.4 GHz RF transceiver to the main control board inside the prompter, which in turn drives the motorized focus lens.

Practical notes

A good teleprompter requires care. The display must be bright enough (800+ nits) to compete with studio lights, yet glare on the glass is the enemy, hence the blackout hood eliminating ambient light reflection. The glass angle is typically fixed at 45° but adjustable for camera height. Talent should never look directly at the camera lens; they look at the glass, which is slightly forward of the lens, creating a subtle eye-line offset that viewers perceive as natural engagement. Professional prompters mount on 15 mm or 19 mm support rods clamped to the camera itself, keeping the glass and lens in optical alignment.