Beam-splitter teleprompter setup with an iPhone

A beam-splitter rig puts the script directly over the lens, so your eye line is perfect by construction. The phone lies flat under a piece of half-silvered glass, the camera shoots through the glass, and you read the reflection. Here is how to set it up with an iPhone and get the text reading the right way round.

How a beam-splitter works

The glass in the hood is coated to reflect about 30 percent of light toward you and pass the rest through to the camera behind it. The phone sits in a tray below the glass, screen up, and its text bounces off the glass into your eyes. Because the reflection comes from below and the camera looks through from behind, two things follow. The text you see is mirrored left to right, so the app has to flip it. And the camera sees only a slight tint, not the text, so nothing shows in the shot. Shooting through glass costs a little light (often half a stop to a stop) and you compensate on the camera.

Picking a rig for a phone

Phone-sized hoods. Compact rigs from Neewer, Glide Gear, Parrot, and similar brands take a phone in a spring clamp under a small glass and mount the camera behind on a plate or on a tripod. They suit mirrorless cameras and DSLRs with modest lenses. Check the tray fits your iPhone with its case, and check the maximum lens diameter the hood accepts.

Tablet-sized hoods. Larger glass and a tray for a 10-inch tablet. An iPhone works in these too with an adapter or a centered clamp, and the bigger glass makes framing easier for longer lenses, at the cost of weight.

Phone-as-camera rigs. Some hoods mount a second phone as the camera behind the glass. If your camera is the iPhone itself, you do not need a beam-splitter at all: run Rolltake on the same phone and use its built-in recording, with the reading line under the front camera. The rig only earns its weight when the camera is a separate body.

Step 1: turn on mirror mode

Open your script in Rolltake, open the prompter's display settings (the Aa button), and switch on Mirror. The text flips horizontally so it reads correctly in the reflection. The flip applies to the prompter view only; the script in the editor stays normal.

Some rigs sit the phone with its top edge toward you rather than away, which turns the reflection upside down. For those, turn on Vertical flip as well. Mirror and vertical flip are saved with the script, so a script you always shoot on the rig remembers both.

If you use the web teleprompter on a tablet or laptop in a larger hood, the same mirror settings are in its display controls.

Step 2: align the glass with the lens

Position the camera so the lens is centered behind the glass and as close to it as the hood allows. Look through the viewfinder or the camera's screen; you should see no edge of the hood. Then sit where you will present and check the reflected text is centered on the lens. If the text appears above or below it, shift the phone in the tray, not the camera. A reading line that lands right on the lens axis is the point of the whole exercise.

Rolltake's reading line can be moved up or down the screen. In a hood, set it so the line lands where the lens is, then adjust the text size so a line of text is about the width of the glass.

Step 3: kill the reflections

The classic beam-splitter problem is a faint image of the phone screen in the shot. Three checks. First, the hood's cloth shroud must fully cover the gap between the lens and the glass; light leaking in from the sides is what causes ghosting. Second, use a dark theme on the phone. Rolltake's Night, Amber, and Green themes are dark backgrounds with bright text, which is what classic glass prompters used for exactly this reason. Avoid the Paper theme in a hood. Third, drop the phone brightness to the lowest level you can still read comfortably. Bright screens bleed.

Step 4: compensate exposure

Open the aperture a third of a stop to a full stop, or raise ISO slightly, to make up for the glass. Set white balance manually; some coatings add a faint tint that auto white balance will chase. Then do one take and check it on a monitor before the real session.

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Step 5: control it without touching the phone

Once the phone is in the tray, you do not want to reach in. Rolltake takes commands from an Apple Watch (play, pause, faster, slower) and from Bluetooth remotes. A Neewer-style BLE remote gives you play/pause, text size up and down, and a three-line nudge in either direction. A keyboard-style clicker or page-turner ring gives you play/pause, speed up and down, and back-a-sentence. Pairing is covered in the remote guide.

Reading in a hood

The eye line is solved, so the remaining tell is rhythm. Keep the column narrow (the glass is small anyway), break the script at breaths, and set the speed so the line arrives as you need it rather than before. The speed guide has a quick calibration. If the phone is farther from your eyes than it would be handheld, push the text size up; in Rolltake it goes to 120 points.

Troubleshooting

Text is backwards. Mirror is off. Turn it on in the prompter display settings.

Text is upside down. The phone is oriented the other way in the tray. Turn on Vertical flip, or rotate the phone.

I can see the phone in the shot. Shroud not sealed, or screen too bright. Seal the gap and lower brightness; switch to a dark theme.

Focus hunts. Some autofocus systems try to focus on the glass. Use manual focus or set a focus limit.

Screen dims mid-take. Rolltake keeps the screen awake while the prompter is open. If it still dims, check Low Power Mode, which overrides that on some iPhones.

Frequently asked questions

Yes. Mirror flips the text horizontally for the glass reflection, and Vertical flip handles rigs that mount the phone the other way up. Both are free and saved per script.

No. If the iPhone is the camera, run Rolltake on the same phone; the reading line sits under the front camera and the app records the take. A beam-splitter only pays off when a separate camera shoots through the glass.

Light is leaking between the lens and the glass, or the screen is too bright. Seal the hood's shroud, lower brightness, and use a dark theme.

Typically half a stop to a full stop, depending on the coating. Open the aperture or raise ISO to compensate, and set white balance manually.

Yes. Use an Apple Watch, a Neewer-style Bluetooth remote, or any keyboard-style clicker or page-turner ring. Play, pause, speed, and back-a-sentence all work without touching the phone.