Do you want to see my real all-sky camera? Visit my all-sky camera in Equipment section. Timelapse of a sky, my own design of all-sky, startrails.
An All-Sky Camera is a specialized, autonomous imaging system designed to capture an uninterrupted 180-degree hemispherical view of the entire sky. While deep-sky astrophotography targets narrow celestial windows over long tracking intervals, all-sky imaging acts as a continuous sentinel—confronting harsh outdoor weather conditions, rapid day-to-night dynamic shifts, and complex data streams to map atmospheric and cosmic phenomena in real-time.
All-sky cameras have evolved from niche meteorological tools into critical components of modern astronomical infrastructure. By monitoring the entire celestial dome simultaneously, these systems capture short-lived, unpredictable atmospheric and astronomical events that standard directional telescopes miss entirely.
To survive continuous exposure to ambient conditions while delivering crisp, low-noise imagery, an all-sky camera requires a precise configuration of optical, sensor, structural, and thermal management hardware.
Material: Acrylic or Borosilicate Glass
Acts as the first layer of environmental defense. Optical clarity is paramount; high-grade acrylic shields the lens from wind, rain, and UV degradation while keeping internal distortion at absolute minimums.
Focal Length: 1.25mm – 2.5mm (f/1.4 – f/2.0)
Ultra-wide lenses specifically tailored to create a circular or cropped hemispherical projection. Fast focal ratios allow maximum photon capture under challenging night skies.
Sensor Class: Back-Illuminated (e.g., IMX462 / IMX178)
Employs high Quantum Efficiency (QE) and exceptionally low read noise. These sensors pick up minor atmospheric variations and faint meteor streaks without requiring active cryogenic cooling.
Architecture: ARM Cortex (e.g., Raspberry Pi 4 / 5)
The operational brain inside the enclosure. It automatically manages capture loops, performs image processing algorithms locally, runs web servers, and streams data packets to host repositories.
System: Continuous Dew Prevention Ring
As the night sky radiates heat, the outer surface of the dome drops below the atmospheric dew point. A dedicated heating resistor ring warms the perimeter, preventing dew condensation and frost formation.
Standard: Power over Ethernet (PoE 802.3af)
Combines network connectivity and high-voltage DC power delivery into a single long-run Ethernet line, minimizing voltage drops and simplifying outdoor routing protocols.
Configure the hardware supply voltage and target thermal dissipation to calculate the optimal values for a parallel array of heating resistors. The system evaluates current dew point parameters in real-time.
Achieving a true 180° field of view requires balancing the image circle projection produced by the fisheye lens against the physical diagonal size of the CMOS sensor. Lenses are engineered to yield a specific circular field diameter; if this diameter is fully enclosed inside the short edge of the sensor, it produces a **Circular Fisheye Image** (displaying the entire sky surrounded by black edges). If the image circle fills or exceeds the sensor boundaries, it delivers a **Diagonal/Cropped Fisheye Image**, maximizing spatial resolution across a slightly narrower horizon footprint.
When mechanically selecting a lens, it is absolutely critical to choose the correct thread mount standard: **C-mount** or **CS-mount**. Both standards share the exact same thread diameter (1 inch, 32 TPI pitch), but they differ fundamentally in their Flange Focal Distance—the mechanical distance from the lens mounting flange to the optical plane of the silicon sensor. For the C-mount standard, this distance is 17.526 mm, whereas for the newer CS-mount, it is only 12.526 mm (a difference of exactly 5.00 mm).
Modern industrial and astrophotography CMOS cameras suitable for building all-sky systems (e.g., ZWO ASI, Player One, Altair series) use a native female CS-mount thread almost exclusively for structural reasons. The following rules apply for correct assembly:
Select an industrial CMOS sensor format and adjust the focal length slider (now up to 8.0mm) to analyze projection cropping factors and real-time field variations.
An all-sky camera operates completely unattended, requiring dynamic software stacks to adjust execution parameters. The primary software challenge is managing the vast contrast shift between intense daylight sun exposure and zero-lux moonless night skies.
Toggle between different target environments to simulate how the capture software automatically modifies exposure calculations and real-time analytical overlays.
| Software Suite | Primary Platform | Target Application | Key Features | Hardware Ecosystem |
|---|---|---|---|---|
| Allsky (Thomas Jacquin) | Linux / Raspberry Pi OS | Web Streaming & Time-lapsing | Automated scripts, Keograms, clean GUI, simple hosting hooks | Raspberry Pi + ZWO / ASI / Pi Cameras |
| RMS (Raspberry Pi Meteor Station) | Linux / Ubuntu Core | Scientific Meteor Tracking | Precise astrometric calibration, orbital trajectory math, Global Network syncing | Raspberry Pi + IPCAM (IMX327/291) |
| AllSky7 Core Software | Ubuntu Linux x86 | Multi-Camera Fireball Tracking | 7-camera overlapping mesh, cloud reduction matrix, sub-second trigger logic | AllSky7 proprietary multi-sensor rigs |
To showcase an entire night's activity, all-sky capture software performs digital frame stacking. Unlike night-sky photography where separate exposures are combined to average out noise, star trail stacking relies on a Maximum Intensity Projection algorithm. The software evaluates the coordinate position $(x, y)$ across all incoming frames, keeping only the brightest pixel value found for that coordinate. As the Earth rotates, stars map concentric circular paths around the celestial poles, while ephemeral entries like fireballs are permanently preserved against the dark background.
Click the action button below to trigger an automated stacking algorithm. Watch how individual night-sky exposures are consolidated to reveal long-duration star tracks and hidden meteor streaks.
Building your own automated all-sky system is a highly rewarding project. Follow this engineering sequence to construct a robust, weatherproof tracking station:
Procure a weatherproof PVC junction box or a 4-inch cylindrical PVC pipe socket. Cut a precise circular aperture in the top cover matching the inner diameter of your acrylic dome. Apply a liberal, continuous bead of marine-grade, UV-stabilized silicone adhesive along the rim, then seat the optical dome firmly over the aperture. Let it cure completely for 24 hours to form a hermetic seal against rainwater ingress.
Mount a series of power resistors or a specialized flexible 12V heating strip around the internal base plate immediately below the dome's perimeter. Ensure the heating elements do not obstruct the lens field of view. This placement allows heat to rise along the inner walls of the dome, warming the optical surface just enough to clear morning condensation.
Thread your wide-angle fisheye lens onto your CMOS camera body. Connect the assembly to a computer and focus on a distant target at infinity during daylight hours. Because atmospheric temperature changes can cause subtle focal shifts, lock the lens position firmly using its locking grub screw. Fix the camera securely along the center axis of the housing.
Mount your Raspberry Pi or single-board computer into the lower section of the box, positioning it away from direct contact with the camera body to isolate electrical heat dissipation. Connect the camera to the processing unit via a USB 3.0 interface line. Wire a PoE (Power over Ethernet) splitter module into the box, linking its output rails to power both the processor board and the dew-heating elements.
Flash an updated Linux distribution onto a high-end endurance microSD card. Clone an open-source all-sky tracking suite (such as Thomas Jacquin's repository) onto the system. Configure your geographic latitude and longitude parameters so the core engine can calculate sun elevations and automatically handle transitions between day-capture and night-capture parameters.
Operating an all-sky camera connects you with global citizen-science initiatives. Interlinking your automated capture feeds with centralized telemetry portals helps create massive observation networks tracking space events across the globe.