Product announcement: QHY461M Photo

The QHY461 PH (photo) is a monochrome BSI CMOS camera with 102 MegaPixel, 16bit AD conversion, highest quantum efficiency with extremely low readout noise.

New - especially for amitious amateur astrophotographs -

The monochrome QHY461M PHis a completely new development of the larger, scientific camera of the monochrome model QHY461M-Pro. It has a more compact body and does NOT have the scientific features of the   QHY461 M/C PRO, BSI Cooled Scientific Cameras (various versions available) . These include the two 2 x 10 GB fiber interfaces, GPS timing, programmable FPGA and the external trigger input. An optional additional water cooling is also not available.

Data is transferred to the PC via a standard USB 3.0 interface. Otherwise, the performance of the QHY461M PH is essentially identical to the scientific version. The main advantage of the QHY461M PH is that it offers all the features and performance important for astrophotography at a much lower price than the QHYM 461-Pro.

Die Daten werden über eine Standard USB 3.0 Schnittstelle an den PC übertragen. Ansonsten ist die Leistung der QHY461 PH im wesentlichen identisch mit der wissenschaftlichen Version. Der Hauptvorteil der QHY461M PH besteht darin, dass sie alle für die Astrofotografie wichtigen Funktionen und Leistungen zu einem deutlich niedrigeren Preis als die QHY461M Pro bietet.

The Sony BSI CMOS IX 461 sensor

The Sony BSI CMOS IX 461 sensor

High-resolution, scientific CMOS sensor Sony IMX 461 with 102 megapixels

The Sony IMX 461 is a BSI Exmore R sensor with similar architecture to its bigger brother, the IMX 411. The sensor measures 44mm x 33mm with a 55mm image diagonal. The array has 11,656 x 8,742 pixels (102 megapixels) at 3.76 µm square pixels. It has maximum quantum efficiency while maintaining high dynamic range.

True 16 bit analog digitization with 65,536 gray levels

The IMX is the world's first scientific CMOS sensor with the AD converter "on board". The data output provides true 16 bit with 65,536 gray levels. Compared to cameras 12/14 bit sensors, the QHY461M PH offers higher sampling resolution and the system gain is less than 1e-/ADU with very low readout noise.

Very low readout noise of only 1 electron with high gain

The QHY461M PH has only one electron readout noise (1 e-) at high gain and a high - for the large dimension of the sensor - readout speed of 1.3 frames per second (fps) at 16 bit, or 2.7 frames per second at 8 bit AD conversion.

Quantum efficiency and low dark current noise

The IMX 461 sensor's BSI technology results in exceptionally high quantum efficiency (max. 90% at 540nm) and features extremely low dark current thanks to SONY's Exmor BSI sCMOS technology. This means that the camera's high sensitivity and low readout noise make it suitable not only for short exposures, but also for long exposures, where dark current noise often dominates.

The quantum efficiency of the IMX 461 as a function of wavelength.

The quantum efficiency of the IMX 461 as a function of wavelength.

Full well capacity of 50 ke- in standard mode and up to 720 ke- in extended mode

Another advantage of the BSI CMOS structure is the increased full-well capacity. This is especially important for sensors with small pixel dimensions. Even with unbinned 3.76 µm pixels, the QHY461 photo has a full-well capacity of 50 ke-. When binning 2x2 to 7.5 µm, the full-well capacity is already 204 ke- and when binning 3x3 to 11 µm, it is 408 ke-. As a further technical highlight, QHY461M PH offers 4 different readout modes of the sensor, including an extended full-well mode. In extended mode, the full-well capacity is 80 ke- unbinned, 320 ke- binned 2x2 and 720 ke- binned 3x3.

Pure raw data

Many DSLR cameras have RAW image output, but it is usually not entirely in RAW format. Upon closer inspection, some traces of noise reduction and hot/coll pixel removal are visible. This can have a negative effect on the image in astronomy. However, the QHY461M PH (and also the other QHY models with 16 Bit AD conversion) provides REAL RAW IMAGE OUTPUT and produce an image consisting only of the ORINAL SIGNALS of the individual pixels, maintaining maximum flexibility for astronomical imaging programs and other scientific imaging applications.

Anti-dew technology and amplifier readout glow

The QHY461M PH's technology is based on nearly 20 years of experience in developing cooled CMOS cameras and provides solutions for icing and dew control. The optical entrance window has a built-in heater to protect dew condensation on the entrance window and the sensor chamber from internal moisture condensation. The sensor itself is kept dry with our desiccant tube base design to control humidity in the sensor chamber. The QHY461M PH shows no amplifier readout glow even with long exposure times.

Advanced high-tech features

Restarting the camera with power on/off

The camera's electronics are designed to use the +12V power supply to reboot the camera WITHOUT having to disconnect and reconnect the USB interface. This means that you can restart the camera by simply disconnecting the +12V and then reconnecting it. This function is absolutely essential for remote operation of a telescope! You can simply use a remotely controllable power supply to restart the camera.

Random thermal noise suppression function

Certain types of thermal noise can change over time in BSI CMOS cameras (keyword: the aging of electronic components). As a result, each image has a unique thermal noise characteristic, making it difficult to reduce by subtracting a dark image.

The QHY461M PH employs innovative proprietary technology that significantly reduces the amount of random thermal noise.

Optimizing USB speed to minimize horizontal banding

CMOS sensors usually show some horizontal banding (see figure below). Usually, these random horizontal bandings are removed by adding multiple raw images so that they do not affect the final image.

However, the so-called periodic horizontal banding is not removed during stacking, so it may be visible in the final image. By adjusting the USB transfer speed in single image or live image mode, the user can adjust the frequency of the CMOS sensor driver, optimize the transfer frequency and thus suppress the horizontal banding.

Left, an example of typical periodic horizontal noise at standard USB transmission frequency. On the right after optimizing the transmission frequency with strong reduction of banding

Left, an example of typical periodic horizontal noise at standard USB transmission frequency. On the right after optimizing the transmission frequency with strong reduction of banding

The most important technical data of the QHY461M PH:

  • Sensor: Sony BSI IMX 461,
  • Sensor resolution: 102 megapixels with the pixel size 3.76 µm x 3.76 µm
  • Sensor size: 44 x 33 mm, sensor diagonal 55 mm
  • AD conversion: unaltered, true 16 bit (65,536 grayscale)
  • Read noise: 1e- to 3.7 e- (depending on readout modes)
  • Data interface: USB 3.0
  • Full well: up to 720 ke- depending on readout mode with high dynamic range
  • Quantum efficiency: max. 90% at 450 nanometers
  • Dark current noise: extremely low
  • Amplifier glow: not available
  • Noise reduction: user selectable
  • Image readout: 4 different modes, user selectable

Here we describe in detail the advantages of the modern Sony IMX 461 CMOS sensor in comparison with a CCD sensor, which was for years the first choice in amateur astronomy imaging.

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