Support — Multiple Flash Photography

📖 About the App

Multiple Flash Photography turns two iPhones into a coordinated flash photography system — no dedicated hardware required. One iPhone acts as the Master, taking the photograph. A second iPhone acts as the Slave, firing its built-in flash to add light to the scene in sync with the Master's shutter.

The app gives you two ways to produce light from the Slave device and two methods to detect and capture the flash moment, so you can balance image quality against reliability to suit your shooting conditions.

⚡ How It Works

📱

Position the Slave iPhone

Place the Slave iPhone where you want the additional light source — to the side, above, or behind the subject.

🎛️

Configure on the Master

Open the Setup screen on the Master iPhone to choose your flash mode (Torch or Flash) and your detection method.

🔦

Slave fires light

When triggered, the Slave emits a burst of light — either a sustained Torch or a true camera Flash — to illuminate the subject.

🖼️

Master captures the frame

The Master detects the flash via video analysis or calibrated timing, then captures the correctly lit photograph automatically.

🔦 Slave Flash Modes

You choose how the Slave iPhone produces light from the Setup screen on the Master iPhone. Each mode has different trade-offs between brightness, duration, and sync reliability.

Torch Mode

Torch (Continuous Light)

Uses the iPhone's continuous torch (flashlight)
Longer light duration — easier to synchronise reliably
Lower peak brightness than a true camera flash
Ideal when sync consistency is more important than maximum light output

Flash Mode

Flash (True Camera Flash)

Uses the iPhone's full-power camera flash
Significantly brighter than Torch mode
Very short duration — requires precise timing
Sync can occasionally be off; works best with Calibrated Timing detection

📸 Flash Detection Methods

The Master iPhone needs to know exactly when the Slave flash fires in order to capture the right moment. Two detection approaches are available — choose based on your priority: robustness or resolution.

Method 1

Video Detection

The Master records a short video and analyses it frame-by-frame to detect the flash burst. When the flash is detected, the relevant frame is automatically extracted as your final image.

More robust — tolerant of slight timing variations. The trade-off is lower image resolution, since the photo is extracted from a video frame rather than captured as a native still.

Method 2

Calibrated Timing

A one-time calibration step measures the precise delay between the Slave flash firing and the Master shutter opening. The app stores this delay and uses it automatically on every subsequent shot.

Full resolution — the Master captures a native still photo. Works best when conditions are consistent. Re-run calibration if you change devices, lighting, or environment.

🚀 Quick Start

Install Multiple Flash Photography on both iPhones.
On the Slave iPhone, open the app and set it to Slave mode. Position it where you want the extra light.
On the Master iPhone, open the Setup screen and choose your Flash Mode: Torch for easier sync, Flash for maximum brightness.
Select your Detection Method: Video Detection for robustness, or Calibrated Timing for full-resolution stills. If using Calibrated Timing, run the calibration process now.
Tap Shoot on the Master. The Slave fires light, the Master detects and captures the perfectly timed frame.

❓ Frequently Asked Questions

Start with Torch mode. Its longer light duration is more forgiving of timing variation and works well with Video Detection. Switch to Flash mode when you need maximum brightness and can pair it with Calibrated Timing for precise sync.

This is usually a sync issue. If you are using Flash mode with Calibrated Timing, try re-running the calibration — ambient light levels and device load can shift the delay. You can also switch to Video Detection, which is more tolerant of timing variation, or switch the Slave to Torch mode for a longer, easier-to-detect burst.

Video Detection extracts a single frame from a recorded video clip, so the output resolution is limited by the video capture resolution rather than the camera's full still-photo capability. For maximum resolution, switch to Calibrated Timing mode, which captures a native full-resolution still image.

Calibration is stored and reused automatically. We recommend re-running it if you change either iPhone, update iOS, or move to a significantly different shooting environment (for example, a much brighter or darker setting than when you last calibrated).

The app requires iOS 16 or later on both the Master and Slave iPhones. Any iPhone with a built-in flash can act as the Slave. For best results, iPhone 8 or newer is recommended for both devices.

✉️ Contact Support

Can't find what you're looking for? Send us an email and we'll get back to you as soon as possible.

Email craig.boudreau@lumenpc.ca We typically respond within 1–2 business days.