Observation Network

High-Speed Video of Lightning

Recording

Cloud-to-cloud flash showing recoil leaders propagating along decaying leader channels — Phantom T2410, RTL3D observation network.

The human eye sees a lightning flash as a single instantaneous burst. Two Vision Research Phantom T2410 cameras record at up to 525,000 frames per second — revealing stepped leaders probing downward, a bright return stroke racing upward, and dart leaders re-igniting spent channels in milliseconds.

2T2410 units

525kfps max

24kfps @ 1 Mpx

24Gpx/s

How it works

The Phantom T2410 uses a back-side illuminated (BSI) CMOS sensor with a global electronic shutter and 24 Gpx/s throughput. At 24,270 fps (1280 × 800) each frame lasts ~41 μs — enough to resolve stepped-leader structure. In binned mode at 100,000 fps (640 × 384) the return-stroke luminosity wave, travelling at roughly one-third the speed of light, can be tracked frame by frame up the channel.

What is captured

Stepped leaders — the invisible-to-eye downward-propagating discharge that branches and pauses in 50 μs steps. Return stroke — the bright upward-propagating wave triggered when a leader contacts ground. Dart leaders — fast restrikes that follow the existing channel in subsequent strokes. Corona and recoil leaders visible in upper branches.

Role in RTL3D

Two Phantom T2410 units provide visual ground truth for the 3D source locations produced by the LF and VHF networks. Frame-by-frame channel images are IRIG/GPS time-stamped and overlaid on the 3D point cloud, confirming that mapped sources trace the actual visible channel geometry and branching structure.

Camera platform

Vision Research Phantom T2410 — compact T-Series high-speed camera with BSI sensor for light-starved outdoor capture.

Vision Research Phantom T2410 high-speed camera, front view — Phantom T2410 — 1280 × 800 BSI sensor, 24 Gpx/s throughput, global shutter.

Phantom T2410 highlights

Throughput — 24 Gpx/s; 24,270 fps at full 1-Mpx resolution (1280 × 800).
Peak frame rate — up to 525,000 fps in standard or binned mode at reduced resolution; 100,000 fps at 640 × 384 binned.
Light sensitivity — BSI CMOS with 84.3% quantum efficiency (mono); suited to night-time lightning against a dark sky.
Exposure — 1.1 μs minimum (190 ns with FAST option); Extreme Dynamic Range (EDR) for saturated return-stroke cores.
Sync & trigger — IRIG in/out, hardware BNC trigger, image-based auto-trigger, and programmable pre/post-trigger capture.

Camera specifications

Model: Vision Research Phantom T2410
Number of cameras: 2 units
Max resolution: 1280 × 800 px (1 Mpx)
Frame rate @ 1 Mpx: 24,270 fps
Max frame rate: 525,000 fps (reduced res.)
Throughput: 24 Gpx/s
Sensor: CMOS BSI, global shutter, 12-bit
Pixel size: 18.5 μm (37 μm binned)
Min exposure: 1.1 μs (190 ns FAST option)
Quantum efficiency: 84.3% mono; 77% color
Memory: 64 / 128 / 256 GB RAM
Lens mount: Nikon F (standard)
Synchronisation: IRIG in/out, GPS time-stamp
Trigger: BNC hardware, image auto-trigger, LF event
Coupled sensors: LF, VHF networks

Why frame rate matters

30 fps (standard video) — the entire lightning event collapses into one or two saturated white frames. Channel structure, branching, and stroke sequence are completely lost.
1,000–10,000 fps — individual strokes become separable; stepped-leader tip luminosity becomes visible as a faint advancing point in each frame.
50,000–525,000 fps — the return-stroke luminosity wave can be tracked upward frame by frame; dart-leader propagation speed can be measured directly from the footage.
Overlaying the frame sequence on RTL3D 3D source maps confirms spatial accuracy of the time-of-arrival solution to within the channel width.