Astronomy Specialist



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The QHY 294M Pro is a popular cooled monochrome camera with large pixels and low noise. It contains the Sony IMX492 back-illuminated sensor with exceptional low light capabilities. The pixels measure 4.63µm, making this camera ideal for medium-long focal length telescopes but also camera lenses and short refractors that may suffer from elongated stars on the borders. Large pixels can mask minor aberrations of the telescope that are generally visible in cameras with small pixels (2-3 µm).

The QHY294M Pro camera is capable unlocking the on-chip binning to provide two readout modes. The first mode reads the sensor in "locked" mode with the original resolution of 11.6Mp, 4.63µm pixel and an bitrate of 14 bits. The second read mode unlocks the binning to produce a resolution of 46.8Mp with 2.315µm pixel and bitrate of 12 bits. 

This camera has a two-stage TEC cooling system that brings the temperature of the sensor around -35C° below ambient for low noise imaging, even in warm climates. The dark current at -20°C is only 0.002 electron/pixels. In addition to thermoelectric cooling, QHYCCD employs a unique thermal noise control technology to reduce CMOS sensor noise to a very low value without affecting the integrity of the raw image. The QHYCCD proprietary technology produces a much better noise reduction than any other astronomy camera in the market. QHYCCD has more than 10 years of experience designing cooled cameras. The QHY 294M Pro employs a full anti-dew technology for both CCD sensor cover glass and the sensor chamber optical window.

The 256MB DDR III memory buffer facilitates the download of images to the computer, especially when USB traffic is high, the writing speed of your computer is slow or occupied in other processes. 

In order to avoid halos around bright stars, the QHY 294M Pro has an AR coated optical window on both sides rather than the common IR/UV cut window. Also, the protection glass of the sensor is AR coated to maximize light transmission and minimize internal reflections. For a better RGB colour balance, it is recommended to use a UV/IR cut filter. 

The camera has 2 gain modes, switching automatically between the two depending on the gain value selected:

  • #0 - Low Gain Mode (LCG): below gain 1600 - the standard mode used for general astrophotography. The readout noise is 6.9e- to 5.2e- decreasing with gain. At gain zero the full well capacity is 65,000e-, ideal for imaging areas with bright stars and strong contrast.
  • #1 - High Gain Mode (HCG): at gain 1600 the camera automatically switches to high gain mode, resulting in ultra low read noise of 1.2e- to 1.6e- and a full well capacity of about 14.5ke-. This mode is ideal for narrowband imaging where long exposures are generally required.


Note: This camera is not supported by The Sky X. We suggest you use alternative software for image capture.


QHY294M Pro system gain

QHY294M Pro read noise

QHY294M Pro full well capacity

QHY294M Pro dynamic range

QHY294M Pro dark current


QHY has designed a number of adapter/spacer kits for the 294M for different setups:

Connection to coma corrector requiring 55mm backfocus and M48 interface with CFW3 + OAG


Connection to Canon EF lens with CFW3

Connection to Nikon F lens with CFW3

Resolution 11.6 Megapixels 4164 X 2796 / 46.8 Megapixels 8328 X 4992 in unlocked mode
Pixel size 4.63 µm (2.315µm in unlock mode)
Sensor size 19.28 mm x 12.95 mm (23.23 mm diagonal)
Exposure range 60µs-3600s
Read noise 1.6e-/1.2e- at HGC mode ; 6.9e-/5.2e- at LGC mode
Dark current 0.002e-/pixel/sec @ -20C
Full well capacity 65,000 e- 
Bit rate 14 bit ADC (12 bit in unlocked mode)
Frame rate 16.5 fps at full resolution (16 bits)
Shutter type Rolling shutter
Cooling ΔT of -35°C Dual Stage TEC cooler
Memory buffer 256 MByte DDR3
ROI Supported
Compatibility Mac, Windows, Linux
Optical window AR coated (both sides)
AR coating on sensor YES
Ports USB 3.0
Compatibility Mac, Windows, Linux
Back focus 17.5mm ±0.3mm
Connections M42 x 0.75 female thread (embedded in camera dovetail)
Dimensions Ø 90 mm; ↨ 103.20 mm
Weight 650 gr
Power supply 12V 3A  (2.1×5.5 mm connector)

QHY294M Pro schematics





  • QHY 294M Pro
  • USB 3.0 cable (1.5m)
  • Screw jack power cable (5.5-2.1mm male jack with locking nut to 5.5-2.1mm female jack)
  • Lighter plug adapter to 5.5-2.1mm power jack
  • Desiccant Drying Tube (desiccant not included)
  • M54 x 0.75 to 2"adapter (2.5mm optical thickness, M48 x 0.75 internal thread for standard 2" filters)
  • M54 spacers - 10mm, 5mm, 3mm, 0.5mm
  • 8x M3 21mm screws


 QHY294M Pro accessories




      Guide to installing QHY and ASCOM drivers for QHYCCD cameras.


      ZWO camera software QHY camera drivers

      ZWO camera software QHY 294M Pro manual

      Customer Reviews

      Based on 1 review
      Randy Womak

      Unreal sensor... very little noise. Works great

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