A beam-splitter teleprompter looks like specialist equipment and costs like it too. It is, in fact, three things: a phone, a sheet of half-silvered glass held at 45°, and something that stops stray light hitting the glass. You can build a good one in an afternoon for less than the price of a month of most video tools.
This guide covers what to buy, how to put it together, and — the part most guides skip — how to configure the prompter so the reflection is actually readable.
What the rig has to do
The whole trick is getting your script and the lens into the same place. When you read from a laptop beside the camera, the viewer sees your eyes pointed slightly off. A beam splitter fixes this by putting the script in front of the lens without the camera seeing it.
The glass is coated so that it reflects some light and transmits the rest. Angled at 45° above your phone, it reflects the screen upward into your eyeline while the camera, sitting behind it, films straight through. You look at your words; the lens looks at your face; the two are on the same axis.
The catch is that a reflection reverses left and right, so the text has to be drawn backwards on the phone in order to read correctly in the glass. That is what mirror mode is for.
The parts list
- Beam-splitter glass — the only part worth spending on. Look for 70/30 (70% transmission, 30% reflection) teleprompter glass, around 3mm thick. A 25 × 20 cm sheet suits a phone. Do not substitute a mirror, and avoid cheap acrylic “two-way” film: acrylic flexes and doubles the reflection, which produces ghosted text.
- A frame to hold it at 45° — laser-cut acrylic brackets, 3D-printed corner pieces, or two wooden triangles cut at 45°. It only has to be rigid and square.
- A hood — black foam board, matte black card, or blackout fabric. This is not optional; without it the camera picks up reflections of the room in the glass.
- A phone mount — a shelf or clamp holding the phone flat, screen up, directly under the glass.
- A tripod that carries the camera and the rig together, so they cannot drift apart between takes.
Building it
- Set the angle. Mount the glass at exactly 45° to the phone. A few degrees out and the reflection lands above or below your eyeline, and you end up looking past the lens instead of into it.
- Position the phone. Screen up, centred under the glass, as close as the frame allows. Distance costs you brightness.
- Put the camera behind the glass. The lens should sit just behind the glass and centred on it. Any gap between the lens and the frame is a place for light to leak in.
- Build the hood. Enclose the space between the lens and the glass, and the space above the phone. Matte black on every inside surface. This single step makes more difference to image quality than anything else on the list.
- Kill the reflections. Wear matte, mid-tone clothing if you can, and keep bright lights out of the glass’s field of view. A white shirt under a hard key light will show up in the reflection.
Setting up the app
Hardware done, the software is quick. In Teleprompter Mirror Pro, open the prompter settings and:
- Turn on Mirror horizontally. The text reverses on the phone and reads correctly in the glass. If your rig hangs the phone above the glass instead of below it, switch on Mirror vertically as well.
- Raise the text size. Reading through glass at arm’s length needs considerably more than reading a phone in your hand. Start at the large preset and go up from there.
- Narrow the frame. Match the readable window to the width of your glass so no line runs off the edge of the reflection.
- Pick Teleprompter-only mode if a separate camera is filming. The phone then acts purely as a prompter and records nothing.
- Pair a remote. Once the phone is inside a hood you cannot reach it. A second phone on the same Wi-Fi handles play, pause, speed and restart — see remote control.
Getting it comfortable
Rehearse one paragraph and watch what your eyes do. If they track downward as the text moves, the type is too small — your eyes are hunting rather than resting. Increase the size until your gaze stays in one spot and the words come to you.
If the reflection is dim, check three things in order: screen brightness at maximum, the hood actually blocking light, and the phone as close to the glass as the frame allows. Those three account for nearly every “my glass is too dark” complaint.
Ghosted or doubled text almost always means the glass is flexing or is genuinely two reflective surfaces. That is the one problem you cannot configure your way out of — it is why proper beam-splitter glass is worth the money.
Do you even need a rig?
Honestly, often not. If you are shooting on the phone itself and holding it at arm’s length, an on-screen prompter over the camera preview puts your eyes close enough that nobody notices. A rig earns its place when you are filming with a proper camera, when the subject sits further from the lens, or when a slightly-off eyeline would undermine the piece — a to-camera address, a piece of paid advertising, an interview cutaway.
Which is the useful test: build the rig when the eyeline is the thing standing between you and a finished video, and not before.