01.05 · Provisional page
ZWO ASI294MM Pro
Cooled monochrome imaging camera
The ZWO ASI294MM Pro is the main imaging camera and sits at the end of the optical train, directly attached to the EFW filter wheel. Its monochrome Four Thirds sensor records light without a colour filter array, allowing the wheel’s filters to build the final colour image or isolate specific wavelength bands. Regulated Peltier cooling can hold the sensor up to 35 °C below ambient temperature, reducing thermal noise and making long exposures more consistent. USB 3.0 and a 256 MB buffer also support fast readout and planetary capture. It can be controlled through ZWO drivers, ASCOM and common astrophotography applications.
Gradual cooling and condensation control
Pro cameras use thermoelectric cooling based on a Peltier module. In my setup I avoid commanding a direct jump from ambient temperature to the working setpoint. Summer temperatures in l’Ampolla often start around +32 °C, while I normally image at −10 °C, so I programme four stages at +20 °C, +10 °C, 0 °C and −10 °C, allowing 10 minutes for each step. With humidity often above 80%, this gradual cool-down helps reduce the risk of condensation inside the camera. If moisture does appear, the four desiccant tablets can become saturated and the chamber must be opened so they can be replaced or regenerated according to the manufacturer’s instructions. The photographs show the assembly that must be removed, the position of the tablets and the sensor that needs to remain free of condensation.
Main capture
Technical specifications
- Sensor
- Monochrome Sony IMX492 · Four Thirds format
- Sensor size
- 19.1 × 13 mm
- Resolution
- 4144 × 2822 pixels · approx. 11.7 MP
- Pixel size
- 4.63 × 4.63 µm
- A/D converter
- 14 bit
- Read noise
- 1.2 e⁻
- Full-well capacity
- 63,700 e⁻
- Exposure range
- 32 µs to 2000 s
- Maximum frame rate
- 16 fps at 14 bit · 19 fps at 10 bit, full resolution
- Buffer memory
- 256 MB
- Interface
- USB 3.0, USB 2.0 compatible
- Cooling
- Regulated set-point Peltier cooling · maximum ΔT −35 °C
- Recommended power
- 12 V DC · 3 A minimum · power supply not included
- Backfocus
- 17.5 mm / 6.5 mm depending on adapter
- Mechanical connections
- Female M42 · male M42 · 50.8 mm nosepiece
- Weight
- 500 g
- Software
- ZWO and ASCOM drivers · Windows, Linux, ARM Linux and macOS
