QHYCCD QHY294M-Pro Mono

A 4/3-inch Sony IMX492 Sensor with 11.7 MP & 46.8 MP Modes

The core of the QHY294M-Pro is its adaptable Sony IMX492 back-illuminated sensor. In its default 11.7 MP mode, the sensor produces large 4.63µm pixels, suited to deep-sky imaging. This mode also features a massive 65,000e- full well capacity, preserving star color in dense fields and capturing subtle details in bright galactic cores.

When you need more resolution you can switch to the extended 46.8 MP mode. The IMX492 has 46.8 million 2.315µm pixels, which Sony bins 2x2 on-chip to create the 11.7 MP array of 4.63µm pixels; the QHY294 Pro can lock or unlock that on-chip binning to give the two readout modes. This dual-mode capability allows the QHY294M-Pro to serve as both a sensitive deep-sky camera and a high-resolution imager in a single 650g body.

Dual Gain Architecture with 1.2e- Read Noise

The QHY294M-Pro incorporates a dual gain system that automatically optimizes performance based on your gain setting. For bright objects or broadband LRGB imaging, the Low Gain Mode (LGC) prioritizes a high full well capacity with read noise between 5.2e- and 6.9e-. When the gain is set to 1600, the camera switches into High Gain Mode (HGC), dropping the read noise to 1.2e- to 1.6e-.

This ultra-low read noise is a significant advantage for narrowband imaging, where signals can be extremely faint. Lower read noise lets faint nebulosity in targets like the Cygnus Loop (NGC 6960) rise above the camera's own noise in shorter sub-exposures.

14-bit ADC, TRUE RAW Data, and Amp Glow Control

The QHY294M-Pro outputs a 14-bit data stream from its analog-to-digital converter (ADC), capturing a wide dynamic range. Unlike consumer DSLRs that may apply noise reduction or hot pixel removal to their "raw" files, QHYCCD provides a TRUE RAW IMAGE OUTPUT. This ensures the data you receive is the original signal from the sensor, maintaining maximum flexibility for advanced post-processing techniques.

QHYCCD's specification says amplifier glow can be reduced during long exposures; glow from the readout electronics, where present, is removed with matching dark frames.

-35°C Cooling, Dark Current Control, and Anti-Dew Heater

Consistent, repeatable data is critical for astrophotography, and the QHY294M-Pro is engineered for thermal stability. The two-stage thermoelectric cooler achieves a regulated temperature of -35°C below ambient, with a dark current of 0.002e-/pixel/sec at -20°C. Regulated cooling lets you build a dark library at a set temperature.

• Anti-Dew Heater: An integrated heater gently warms the AR+AR coated optical window, preventing dew formation during humid nights.
• Chamber Humidity Control: The sensor chamber is protected from internal humidity condensation via a silicon gel tube socket, ensuring the sensor itself remains dry.

256MB DDR3 Buffer Ensures 16.5 FPS Stable Data Transfer

To prevent dropped frames and ensure reliable data transfer, the QHY294M-Pro includes a 256MB DDR3 image buffer. This onboard memory acts as a high-speed cache, storing frames from the sensor before they are sent to your computer over the USB 3.0 interface.

In the standard 11.7 MP mode, the camera can deliver a full-resolution frame rate of 16.5 FPS at 14-bit depth. With the Region of Interest (ROI) function the rate increases, reaching 87 FPS for a 480-line window.

17.5mm Back Focus for Flexible Optical Train Integration

The QHY294M-Pro features a standard 17.5mm back focus distance, measured from the front M42x0.75 female thread to the sensor. This spacing is designed to integrate cleanly with QHYCCD's ecosystem of accessories, particularly the CFW3M-US filter wheel, which consumes 17.5mm of back focus. The CFW3M-US with the optional OAG-M (10mm) is the recommended pairing for sensors of this size, and the adapter combinations bring the train to the 55mm that many correctors require.

For more complex setups, this 17.5mm distance provides ample room to add an off-axis guider, such as the QHYOAG-M, between the filter wheel and the telescope. If you do not use an OAG, put a 10mm spacer from the adapter kit in its place.

The Advantages of Monochrome LRGB & Narrowband Imaging

As a monochrome camera, the QHY294M-Pro offers the highest possible resolution and sensitivity from the IMX492 sensor. By capturing images through separate Luminance, Red, Green, and Blue (LRGB) filters, you can gather significantly more signal for each color channel compared to a one-shot color camera.

A mono sensor suits narrowband imaging. Using filters that isolate specific wavelengths of light, like Hydrogen-alpha (Hα), Oxygen-III (OIII), and Sulphur-II (SII), you can cut through light pollution and capture high-contrast images of emission nebulae. The QHY294M-Pro's low read noise in HGC mode helps with these faint exposures.

Unified Control with the All-In-One Driver Pack

QHYCCD provides a comprehensive All-In-One software package to manage the QHY294M-Pro. This installer includes system drivers, the EZCAP_Qt capture software, and ASCOM drivers for universal compatibility with third-party software. It also contains SDKs for direct integration with popular applications like N.I.N.A. and SharpCap, ensuring you can control the camera from your preferred imaging suite.

The ASCOM driver allows any ASCOM-compliant software to control the camera's exposure, cooling, gain, and other settings.

Stable 12V DC Power and First Light Guide

The QHY294M-Pro requires a stable 12V DC power supply (rated for 11V to 13.8V) to operate the camera and its two-stage TEC cooler. QHYCCD's setup guide says the input voltage cannot be lower than 11.5V, otherwise the camera will not work normally. It is recommended to use a high-quality power supply and avoid excessively long power cables that can cause a voltage drop.

For a successful first connection, always connect the 12V power supply to the camera before connecting the USB 3.0 cable to your computer. This ensures the camera is properly powered on and will be recognized by the operating system when the USB connection is established.