Product Review - QHY 168M

This is a prototype version of the the very popular QHY168C, except this one has been factory debayered by QHY to produce a fully monochromatic camera. The camera is mounted on a 12" solid tube Ritchey-Chretien telescope made by AstroTech, which has itself been fitted with the Optec Gemini Rotating Focuser. The filter wheel is a QHYCFW2-M with a 7 position 36mm Carousel. We gave just received and fitted a new set of Optolong Narrowband Filters which have blackened edges that are meant to reduce the halo problems.

High Performance
The QHY168C uses an APS-C format, 16 Megapixel, 14-bit CMOS sensor, the Sony IMX071. This sensor is also used in the Nikon D5100 camera. It has 3.2e- read noise at lowest gain and 2.3e- read noise at unity gain (system gain = 1e/ADU). The QHY168C also has a nice dynamic range close to 14 stops.

True RAW Image Output
While the QHY168C has the same CMOS sensor as the D5100, unlike the consumer camera the QHY168C offers True RAW Image output. In the DSLR implementation there is a RAW image output, but typically it is not completely RAW. Some evidence of noise reduction and hot pixel removal is still visible on close inspection. However, the QHY168C offers TRUE RAW IMAGE OUTPUT and produces an image comprised of the original signal only, thereby maintaining the maximum flexibility for post-acquisition astronomical image processing programs.

Unique Thermal Noise Reduction Technology
In addition to efficient 2-stage 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. This proprietary technology can be found to improve noise performance across the whole 165/168/247/367 product line, producing much better noise reduction than any competing camera model.

Zero Amplifier Glow
QHY168C has zero amplifier glow no matter how long the exposure time.

Anti-Dew Technology
QHYCCD has more than 10 years of experience designing cooled cameras. The QHY168C receives the benefit of that decade of design work by featuring full anti-dew technology for both CCD sensor cover glass and the sensor chamber optical window. The QHY168C has an electric heating board for the chamber window to prevent the formation of dew and the sensor itself is kept dry with our silicon gel tube socket design for control of humidity within the sensor chamber.

AR+AR Optical Window
In order to avoid halos around bright stars the QHY168C has a AR+AR coated optical window rather than the common IR cut window for Single-Shot Color cameras. This permits full access to the red wavelength of H-alpha and SII without attenuation by the window coating. For RGB color balance, without passing the near IR wavelengths above 700nm, a separate removable 2-inch UV/IR filter with the desirable passband characteristics is placed in a custom filter holder in front of the camera.

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