Choosing a Camera for SkyNode

SkyNode uses the all-sky camera as an instrument, not just a viewfinder: cloud detection, the clear/overcast verdict, and sky-quality readings are all photometric measurements made on the frames. That shapes what hardware works. The good news: what works is simple, and you may already own most of it.

What actually matters

• A raw-sensor USB astronomy camera. Photometry needs the sensor’s actual, linear pixel values. Astronomy cameras deliver raw frames; that is the whole requirement.
• A true fisheye lens. The point of an all-sky camera is the whole sky, horizon to horizon. ARIS fits your lens’s actual projection during calibration, so the fisheye view maps correctly onto the planning chart in true altitude and azimuth.

The reference setup is a ZWO ASI676MC-class camera behind a fisheye lens. A common budget start: a spare guide-class camera you already own, plus an inexpensive fisheye lens — guide cameras are raw astronomy sensors, which makes them measurement-grade from day one.

Why a Wi-Fi security camera won’t work

It is tempting to point a cheap outdoor Wi-Fi camera at the sky, and for “is it raining?” it is fine. For sky measurements it honestly is not, and the reasons are baked into the hardware:

• IR-cut filters and auto day/night modes change what the sensor sees, unpredictably.
• Built-in noise reduction smears out exactly the faint signal — stars, thin cloud — that detection depends on.
• Video compression destroys the pixel-level photometry that the clear-sky reference and sky-quality readings are calibrated against.

Consumer Wi-Fi and security cameras are therefore not supported for sky measurements. If one is already mounted on the house, keep it for the driveway — and give the sky a raw sensor.

Mounting: it needs less than you think

• Pack-in setups: if the rig comes inside every morning, so can the camera. A bare camera and fisheye on a small stand, pointed at the zenith, is a legitimate all-sky setup — no dome, no housing, no drilling.
• Permanent installs: a camera that lives outside keeps the classic weatherproof housing with a clear dome. If you already run one, ARIS plugs into it as-is.
• Dew is the one thing that doesn’t pack away. On humid nights a dome or front lens fogs just like your optics do. A ~$15 USB dew-heater ring solves it for either posture.

Tip

The sky mask is learned automatically from your camera’s own frames, so a less-than-perfect horizon — trees, a roofline, the stand itself — costs you nothing but the sky it physically blocks. Put the camera where it is convenient, not where it is perfect.

Where it connects

Three paths, detailed in Set Up SkyNode:

• Today: the camera runs under your existing all-sky capture stack, with the ARIS companion service alongside — available now.
• Rolling out: the camera plugs straight into the rig computer as a third camera role, and ARIS drives it — nothing else to install.
• In development: the dedicated SkyNode — a $25-class Raspberry Pi board that carries the camera where no cable reaches.