The QHY294Pro is a 4/3-inch camera equipped with SONY's Back Side Illuminated IMX 492 mono sensor. The QHY294 Pro series camera can lock and unlock on-chip binning to enable two readout modes:
- Mode 0: 11.7 megapixels (4,164 x 2,796 pixels) at 4.63 µm pixel size with 14-bit data depth
- Mode 1: 46.8 megapixels at 2,315 µm pixel size with 12-bit data depth
The IMX492 chip has 46.8 million 2.315um pixels, which are arranged by Sony in 2×2 binning on the chip to produce the specified 11.7 million 4.63um pixels. This on-chip binning can be turned on or off to produce the two modes described above.
Frame Rate (Standard 11.6mega pixel mode)
- Full Resolution: 16.5 FPS @ 14-bit
- ROI: 2160 lines 21 FPS, 1080 lines 41 FPS, 960 lines 46 FPS, 768 lines 56 FPS, 480 lines 87 FPS, 240 lines 156 FPS, 100 lines 290 FPS
Frame rate (47 mega pixel mode): 8340*5644 4FPS@14bit and 8bit
BSI, back-illuminated CMOS structure:
One benefit of the back-illuminated CMOS structure is improved sensitivity. In a typical front-illuminated sensor, photons from the target entering the photosensitive layer of the sensor must first pass through the metal wiring that is embedded just above the photosensitive layer. The wiring structure reflects some of the photons and reduces the efficiency of the sensor.
In the back- illuminated sensor the light is allowed to enter the photosensitive surface from the reverse side. In this case the sensor’s embedded wiring structure is below the photosensitive layer. As a result, more incoming photons strike the photosensitive layer and more electrons are generated and captured in the pixel well. This ratio of photon to electron production is called quantum efficiency. The higher the quantum efficiency the more efficient the sensor is at converting photons to electrons and hence the more sensitive the sensor is to capturing an image of something dim.
Cooling & Anti-dew Control: In addition to dual stage TE cooling, QHYCCD implements proprietary technology in hardware to control the dark current noise. The optic window has built-in dew heater and the chamber is protected from internal humidity condensation. An electric heating board for the chamber window can prevent the formation of dew.
Sealing Technology: Based on almost 20-year cooled camera design experience, The QHY cooled camera has implemented the sealing control solutions. The sensor itself is kept dry with our silicon gel tube socket design for control of humidity within the sensor chamber. By the way, there’s no oil leaking.
Mono or Color?
Mono:
- Capable of advanced techniques (LRGB, narrowband)
- Additional applications (spectrometry, photometry)
Colour:
- Convenient for RGB imaging
- No need for expensive filters and filter wheels
Both types of camera are capable of creating stunning astroimages, we can only recommend you pick the one that suits you best!
Our expert comment:
QHY is the only manufacturer to use Sony IMX sensors of "industrial grade" quality for its monochrome cameras. This industry standard means fewer pixel errors and a significantly longer service life. The semiconductors are mounted on a material that is particularly resistant to thermal stress caused by repeated cooling/heating cycles.
QHY cameras are therefore often more expensive than cameras from other manufacturers with the same sensor, as these usually only use consumer grade chips.
(Stefan Taube)
