Teleprompter mirror: how beamsplitter glass works and how to set one up

If you've ever watched a news anchor look straight down the barrel of the camera while reading a full script, you've seen a teleprompter mirror at work. The trick is a piece of glass sitting at a 45-degree angle in front of the lens, and it's the reason the presenter can read and make eye contact at the same time.

The mirror itself is only half the setup, though. The other half is software: the text on your screen has to be flipped, or it shows up backwards in the reflection. This guide covers what a teleprompter mirror actually is, how the optics work, your hardware options, and how to set up the flipped text so everything reads correctly on camera.

What a teleprompter mirror actually is

A teleprompter mirror is not a regular mirror. It's a beamsplitter, also called two-way or one-way glass. Instead of reflecting all the light that hits it, it splits the light: some reflects off the surface, and some passes straight through. That dual behavior is the whole point.

In a teleprompter rig, the glass is mounted at roughly 45 degrees in front of the camera lens. A screen — a monitor, tablet, or phone — sits below (or sometimes above) the glass, facing it. The screen's image reflects off the angled glass toward the presenter, who reads it like text floating in front of the lens. Meanwhile, the camera sits behind the glass and shoots straight through it, capturing your face without picking up the reflected text.

Why the text has to be mirror-flipped

Here's the part that trips people up. When you look at text in any mirror, it reverses left-to-right. Hold a book up to your bathroom mirror and the words run backwards. A beamsplitter does the same thing to your script.

So if you display normal text on the screen below the glass, you'll read it as a backwards, unreadable mess in the reflection. To cancel that out, the prompter software flips the text before it hits the glass. The screen shows mirror-image text, the glass reverses it again, and the two reversals cancel — leaving you with normal, readable words floating over the lens.

Which direction you flip depends on how your rig is built. Most setups need a horizontal flip (left-to-right mirroring). But if your screen sits above the glass instead of below it, or the glass is angled the other way, you may need a vertical flip (top-to-bottom) instead. A good prompter app offers both. DocPrompter has horizontal and vertical flip, so it works whether your screen is mounted below or above the beamsplitter.

Your hardware options

Teleprompter mirror hardware ranges from broadcast studio gear to clip-on mounts that cost less than a tripod.

Studio and pro rigs

These are the big units you see in TV studios and on professional sets. The glass is large, the hood is sturdy, and the rig is built to take a full-size camera plus a dedicated monitor. They're precise and durable, but they're heavy, expensive, and overkill for most solo creators.

Phone and tablet beamsplitter mounts

This is where most people start. These compact rigs hold a beamsplitter at 45 degrees with a tray underneath for your phone or tablet, and a mount for your camera (or a second phone) behind the glass. They fold up, sit on a tripod, and cost a fraction of a studio rig. The glass quality varies, so it's worth reading reviews — cheap glass can dim your image or add a slight haze.

The software side: setting up the flip

The mirror handles the optics, but the text comes from a prompter app. Here's how to get the two working together.

1. Load your script. With DocPrompter you paste a Google Docs link or raw text and it becomes a fullscreen scrolling prompter — nothing to install.
2. Turn on mirror mode. Use horizontal flip for the common setup where your screen sits below the glass. If your text still reads backwards in the reflection, switch to vertical flip instead.
3. Check the reflection, not the screen. Look at the beamsplitter from the camera's position. The words should read normally there — the screen itself will look flipped, and that's correct.
4. Set your scroll mode. Manual gives you full control, fixed-time scrolls at a steady pace, and voice-follow moves the text as you speak and pauses when you pause — handy in a rig where you can't reach the controls.
5. Adjust font size, width, and line height so a comfortable amount of text sits in your eye-line, then add an eye-line marker to keep your gaze locked at lens height.

Because DocPrompter runs in the browser and installs as a fullscreen PWA, you can run it on whatever screen fits under your glass — a phone, a tablet, or a laptop — without hunting for an app for each device. Screen wake-lock keeps the display from sleeping mid-take.

When you don't need a mirror at all

Plenty of great videos are shot without any beamsplitter. If you don't have a rig — or don't want one — you can place your prompter screen right next to the lens and read normal, un-flipped text. Your eyes will be a touch off-axis, but with the screen close to the lens and a bit of distance between you and the camera, most viewers won't notice.

This is the simplest setup: a phone propped beside your camera with the script scrolling, no glass involved. For that, you don't flip anything — you just want a clean fullscreen prompter. See our guide to running a teleprompter on your phone, and if you tend to drift while reading, the tips in recording without memorizing will help you sound natural either way.