With the advantage of low readout noise and high-speed readout, CMOS technology has revolutionized astronomical imaging. A monochrome, back-illuminated, high-sensitivity, astronomical imaging camera is the ideal choice for astro-imagers.
The QHY268M/C is a new generation of back-illuminated CMOS cameras with true 16-bit A/D and 3.76um pixels. This new Sony sensor is an ideal CMOS sensor exhibiting no amplifer glow. 16-bit A/D gives high resolution sampling of the whole full well range. Digitizing 0-65535 levels yields a smooth image with continuous gradation of greyscale levels. The QHY268M/C is a cooled, back-illuminated, CMOS camera based on the Sony IMX571 sensor with native 16-bit A/D and 3.76um pixels.
1GB DDR3 image buffer
In order to provide smooth uninterrupted data transfer of the entire 26MP sensor at high speed, the QHY268 has 1GB DDR3 image buffer. The pixel count of the latest generation of CMOS sensors is very high resulting in greater memory requirements for temporary and permanent storage. The QHY268 has adopted a large-capacity memory of up to 1GB. Data throughput is doubled. This large image buffer meets the needs of high-speed image acquisition and transmission of the new generation of CMOS, making shooting of multiple frames smoother and less stuttered, further reducing the pressure on the computer CPU.
USB Re-connection by 12V Power on/off
The QHY600 / 268 camera’s USB interface to the computer can be connected or disconnected by turning on and off the camera’s 12V power, without the need to plug and unplug the USB cable. This technology enhances the controllability of the camera when used in a remote station. You only need to remotely control the 12V power supply of the camera, or the power of the camera AC adapter, to achieve remote USB connecting and reconnecting of the camera.
Random change thermal noise suppression function
You may find some types of thermal noise can change with time in some back-illuminated CMOS cameras. This thermal noises has the characteristic of the fixed position of typical thermal noise, but the value is not related to the exposure time. Instead, each frame appears to have its own characteristics. The QHY600 / 268C uses an innovative suppression technology that can significantly reduce the apparent level of such noise.
Extended Full Well Capacity and Multiple Read Modes
With a pixel size of 3.76um, these sensors already have an impressive full well capacity of 51ke. Nevertheless, QHYCCD has implemented a unique approach to achieve a full well capacity higher than 51ke- through innovative user controllable read mode settings. In extended full well readout mode, the QHY600 can achieve an extremely large full-well charge value of nearly 80ke- and the QHY268C can achieve nearly 75ke-. Greater full-well capacity provides greater dynamic range and large variations in magnitude of brightness are less likely to saturate. The QHY600 / 268C have three readout modes with different characteristics.
Native 16 bit A/D
The new Sony sensor has native 16-bit A/D on-chip. The output is real 16-bits with 65536 levels. Compared to 12-bit and 14-bit A/D, a 16-bit A/D yields higher sample resolution and the system gain will be less than 1e-/ADU with no sample error noise and very low read noise.
One benefit of the back-illuminated CMOS structure is improved full well capacity. This is particularly helpful for sensors with small pixels. Even with unbinned, with 3.76um pixels, the QHY600 has a full well capacity of more than 51ke-. When binned 2×2 to 7.5um the full well is 196ke- and when binned 3×3 to 11um the full well is 441ke-.
Zero Amplify Glow
This is also a zero amplifer glow camera.
Based on almost 20-year cooled camera design experience, The QHY cooled camera has implemented the fully dew control solutions. 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 and the sensor itself is kept dry with our silicon gel tube socket design for control of humidity within the sensor chamber.
In addition to dual stage TE cooling, QHYCCD implements proprietary technology in hardware to control the dark current noise.
Multiple Readout Modes is a new function for newer QHY Cameras. Different readout modes have different driver timing, etc., and result in different performance. The QHY268 currently has four readout modes, and more modes will be added in the future. These readout modes are currently supported in the QHY ASCOM Camera Driver, SharpCAP software and the N.I.N.A software.
Readout Mode #0 (Photographic Mode). In this mode there is a drop in the noise between Gain 25 and Gain 26. We recommend setting the Gain to 26 to begin. At this setting the full well is 27ke- and readout noise is 2.7e-. For every long exposures you can lower the gain from this point to increase the full well capacity.
Readout Mode #1 (High Gain Mode). Please note there is a HGC/LGC switch point at gain55 to gain56. Gain0-55 uses LGC and Gain55-100 uses HGC.
Readout Mode #2 (Extended Fullwell Mode).
Now QHY600 adds #3 mode Extend Fullwell 2CMSIT (yellow curve). The advantage of this mode is that it has the same full well value and system gain as the #2 mode Extend Fullwell, but the read noise is reduced by about 1.3 times.
This function needs to be used with 2020.6.26 or newer SDK. If your software cannot display this mode, please download the QHYAllInOne installation package to update the SDK in the software.
The differences between the Photographic and Professional versions include:
- Professional version has a high-speed fiber interface and USB3.0 interface. Photographic version has only a USB3.0 interface.
- Professional version may have more on-camera DDR3 memory than the Photographic version.
- Professional version has rich, external, expandable I/O signals as well as a rich resource that allow the user to customize the FPGA inside the camera.
- Professional version is more expensive than Photographic version.
- Professional version has a longer body to accommodate the length of the optical fiber interface.
- Camera Window is AR+AR
|Image Sensor||SONY APS-C CMOS Sensor IMX571|
|Sensor Type||Back Illuminated (BSI)|
|Pixel Size||3.76um x 3.76um|
|Sensor Surface Glass||Multi Layer AR coating|
Effective Image Area
6280*4210 (includes the optically black area and overscan area)
Full Well Capacity
75ke- or above in extended full well mode
Native 16-bit (0-65535 greyscale) A/D
|Full Frame Rate|
Full Resolution 6.8FPS @8BIT 6FPS @16BIT
2048lines 13.6FPS @8BIT 11.5FPS@16BIT
1080lines 25.4FPS @8BIT 19.5FPS@16BIT
768lines 35FPS @8BIT 25FPS@16BIT
480lines 50FPS @8BIT 34FPS@16BIT
|Read Noise||1.1e- High Gain, 3.5e- Low Gain|
(5.3e- to 7.4e- in extended full well mode)
|Dark Current||0.0005e/pixel/sec @ -20C 0.001e/pixel/sec @ -10C|
|Zero Amplifier Glow||Yes|
|Exposure Time Range||30us – 3600sec|
|Firmware/FPGA upgrade||Fully Support. via Camera USB port|
|Shutter Type||Electronic Shutter|
|Computer Interface||USB 3.0|
|Built-in Image Buffer||1GByte DDR3 Memory|
Two-stage TEC cooler
Less than 1S lower than ambient temperature -30C in continuous mode
More than 1S continuous mode or lower than ambient temperature -35C in single frame mode
|Center inclination adjustment *||Yes|
|Extended Fullwell Mode*||Yes|
|QHY268C: M54/0.75 （with CAA）and M48 (with standard adapter)|
QHY268M: Support M54 and M48 (with standard adapters )
|Optic Window Type||AR+AR High Quality Multi-Layer Anti-Reflection Coating|
Back Focal Length*
QHY268C: 17.5mm (without CAA)
This intercept does not include CAA. If CAA is used, it increases by 6mm (23.5mm total). Please check the mechanical drawing below for details.
Note: The 17.5mm (±0.3) rear intercept does not include the thread. After the central inclination adjustment ring is added, the M54*0.75 internal thread is included.QHY268M: 12.5mm (with CAA)
If used with the QHY filter wheel, the actual calculated intercept is 12.5mm. The actual BFL (the intercept from the CMOS chip to the top of the camera) is 14.5mm. Since most uses will match CFW with monochrome cams, please take 12.5mm as major reference. Check the mechanical drawing below for details.
Note 14.5mm rear intercept does not include adapter thread, which must be used with adapters of various sizes through the top 6 screw holes.