Product Overview
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 amplifier glow. 16-bit A/D gives high-resolution sampling of the whole full well range. Digitizing 0-65535 levels yields a smooth image with a 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.
Internal Humidity Sensor
QHY268M has a unique internal humidity sensor (while QHY268C doesn’t). The Blue curve shown below represents humidity.
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.
BSI: One benefit of the back-illuminated CMOS structure is improved full well capacity. 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.
TRUE RAW Data: 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. This can have a negative effect on the image for astronomy such as the “star eater” effect. However, QHY Cameras offer 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 and other scientific imaging applications.
Zero Amplify Glow: This is also a zero amplifer glow camera.
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.
Multiple Readout Modes are special for QHY 16-bit Cameras (QHY600/268/461/411). Different readout modes have different driver timing, etc., and result in different performance. See details at “Multiple Readout Modes and Curves” Part.
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 QHY600/268/461/411 use an innovative suppression technology that can significantly reduce the apparent level of such noise.
UVLO（Under Voltage Locking) is to protect the electronic device from damage caused by abnormally low voltages.
Our daily life experience tells us that the actual operational voltage of an electrical device must not significantly exceed the rated voltage, otherwise it will be damaged. For such precision equipment as cameras, long-term work at too low input voltage can also be detrimental to the working life of the camera, and may even make some devices, such as power manager, burn up due to long-term overload. In the all-in-one driver and SDK after 2021.10.23 stable version, the camera will give a warning when the input voltage of the camera is below 11V.
It is common behavior for a CMOS sensor to contain some horizontal banding. Normally, random horizontal banding can be removed with multiple frame stacking so it does not affect the final image. However, periodic horizontal banding is not removed with stacking so it may appear in the final image. By adjust the USB traffic in Single Frame mode or Live Frame mode, you can adjust the frequency of the CMOS sensor driver and it can optimize the horizontal banding appeared on the image. This optimized is very effective to remove the periodic banding in some conditions.
A typical Periodic Horizontal Noise under certain USB_TRAFFIC values.
After Adjusting the USB Traffic to avoid the periodic horizontal noise.
The camera is designed to use the +12V to reboot the camera without disconnecting and reconnecting the USB interface. This means that you can reboot the camera simply by shutting down the +12V and then powering it back on. This feature is very handy for remote controlling the camera in an observatory. You can use a remotely controlled power supply to reboot the camera. There is no need to consider how to reconnect the USB in the case of remote control.
If you have certain needs for the frame rate of the device, such as meteor monitoring, etc., you can make selective updates.
Since most of the software that provides continuous mode (i.e. video output), such as SharpCap, only supports 8-bit or 16-bit mode, you need to select 8-bit mode output to achieve frame rate improvement in 12-bit High-Speed Mode.
Data comparison (USB3.0 at full resolution):
Before upgrade: 8-bit, 6.8fps
After upgrade: 8-bit, (12-bit out), 14.5fps max.
The implementation of this function requires updating the firmware, driver, and corresponding software SDKs at the same time.
To update the driver and software SDK, download the Allinone package (BETA) 20220817 or newer, and check the system driver and the required SDK to update them.
Click the link to download the Allinone（BETA）20220817: https://www.qhyccd.com/file/repository/publish/AllInOne/220817/QHYCCD_Win_AllInOne.22.08.17.00.exe
Firmware update: You need to download firmware update package 20220824 or newer. If you have previously kept an older version of the firmware upgrade tool locally, please discard it. The zip package contains the firmware upgrade tool, the new version of QHY268 firmware, and firmware upgrade instructions. Please read the upgrade instructions in the firmware installation package carefully. If you encounter any problems during the upgrade, please contact QHYCCD.
Click the link to download the firmware upgrade tool: https://www.qhyccd.com/file/repository/publish/firmware_update/220818/QHYCCD_firmware_upgrade.zip
Firmware Upgrade Instructions: https://www.qhyccd.com/qhy268-firmware-upgrade-instructions/
Readout Mode #0 (Photographic Mode)
Readout Mode #1 (High Gain Mode)
Readout Mode #2 (Extended Full Well Mode)
Readout Mode #3 (Extend Full Well Mode-2CMS)
Readout Mode #4 (Photographic Mode-2CMS)
Readout Mode #5 (High Gain Mode-2CMS)
Please pay attention to the values of the important gain, like gain 26 (unity gain), gain 56 (high gain mode)
Absolute QE
Multiple Readout Modes are special for QHY 16-bit Cameras (QHY600/268/461/411). Different readout modes result in different performance. These readout modes are currently supported in the ASCOM, SharpCap and N.I.N.A.
Photographic DSO Mode (Mode #0)
This mode is suitable for most DSO imaging situations. Since there is a drop in the noise between Gain 25 and Gain 26 (unity gain), we recommend it as default gain setting; however, gain0 is also good enough for a 16-bit sensor.
High Gain Mode (Mode #1)
This mode is something like double native iso of some new digital cameras, whose danamic range can greatly incerase at the vary high iso value, like iso800, iso3200, etc. The high gain mode provide such improvement for QHYCCD 16bit cameras. We recommend you choose this mode when you have to capture at high gain, for example, a vary dark object. Please note the switch point of HGC/LGC of QHY600/268/461 is 56. That means you must set Gain 56 to make the best of it.
Extended Fullwell Mode (Mode#2)
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 Fullwell Mode, the QHY600 can achieve an extremely large full-well charge value of nearly 80ke- and the QHY268 can achieve nearly 75ke-. Greater full-well capacity provides greater dynamic range and large variations in magnitude of brightness are less likely to saturate.
2CMS Modes
Extended Fullwell Mode-2CMS (Mode#3)
Photographic DSO Mode-2CMS (Mode#4)
High Gain Mode-2CMS (Mode#5)
Based on the three basic modes above, 2CMS mode can greatly reduce readout noise by secondary sampling while keeping the same full well value and system gain. We prefer 2CMS modes than basic modes in astrophotography. By the way, the recommend gain values are the same as their basic modes.
| Model | QHY268M/C PH |
| CMOS Sensor | SONY IMX571 |
| Mono/Color | Both Available |
| FSI/BSI | BSI |
| Pixel Size | 3.76μm*3.76μm |
| Effective Pixel Area | 6252*4176 |
| Total Pixel Area | 6280*4210 (include optical black area and overscan area) |
| Effective Pixels | 26 Megapixels |
| Sensor Size | APS-C |
| A/D | Native 16-bit (0-65535 greyscale) A/D |
| Full Well Capacity (1×1, 2×2, 3×3) | Standard Mode 51ke- Extended Full Well Mode >75ke- |
| Frame Rates | Full Resolution: 6.8FPS@8bit, 6FPS@16bitROI: 2048lines, 13.6FPS@8bit, 11.5FPS@16bit 1080lines, 25.4FPS@8bit, 19.5FPS@16bit 768lines, 35FPS@8bit, 25FPS@16bit 480lines, 50FPS@8bit, 34FPS@16bit |
| Readout Noise | 1.1e- to 3.5e- (5.3e- to 7.4e- in Extended Full Well Mode) |
| Dark Current | 0.0005 e-/pixel/sec@-20℃， 0.001 e-/pixel/sec@-10℃ |
| Exposure Time Range | 30μs-3600sec |
| Recommend Gain* | 30 (PH Mode, or Extended Full Well Mode) 56 (High Gain Mode) *Learn more at the introduction of “Readout Modes”. |
| Amp Control | Zero Amplifer Glow |
| Shutter Type | Electronic Rolling Shutter |
| Computer Interface | USB3.0 |
| Built-in Image Buffer | 1GB DDR3 Memory Buffer |
| Cooling System | Dual Stage TEC cooler: – Long exposures (> 1 second) typically -35℃ below ambient – Short exposure (< 1second) high FPS, typically -30℃ below ambient（Test temperature +20℃） |
| Optic Window Type | AR+AR High Quality Multi-Layer Anti-Reflection Coating |
| Telescope Interface | Support M54 or M48 (Combined with adapters ) |
| Back Focal Length *Learm more: https://www.qhyccd.com/adapters/ |
14.5mm（±0.2） |
| Anti-Dew Heater | Available |
| Humidity Sensor | Available in QHY268M only |
| Firmware/FPGA remote Upgrade | Available via Camera USB port |
| Weight | 810g |
Specifications
QHY268C MEDIUM FORMAT SCIENTIFIC CMOS CAMERA SPECIFICATIONS | |
| Model | QHY268C |
| Image Sensor | SONY APS-C CMOS Sensor |
| Sensor Type | Back Illuminated (BSI) |
| Pixel Size | 3.76um x 3.76um |
| Color / Mono Version | Only Color Version Avaliable |
| Sensor Surface Glass | Multi Layer AR coating |
Effective Pixels | 26 Megapixels |
Effective Image Area | 6364*4210 (includes the optic black area and overscan area) |
Full Well Capacity (1x1, 2x2, 3x3) | 44ke- / 176ke- / 396ke- |
A/D | 16-bit (0-65535 greyscale) for 1X1Binning 18bit in 2X2 19BIT in 3X3 20BIT in 4*4 software Binning |
Sensor Size | APS-C format |
| Full Frame Rate | 6FPS |
| Read Noise | 1e to 4e |
| Dark Current | TBD |
| Exposure Time Range | 30us - 3600sec |
| Firmware/FPGA upgrade | Fully Support. via Camera USB port |
| Non-volatile memory / On camera storage | Build-in total 64MByte Flash Memory. 10MBytes user-accessible space for stellar ROI frames for analysis of exoplanet investigation, occultations, atmospheric seeing messurement, focus , optic analysis etc. Support 100*100 image x 500frames 50*50 image x4000frames. 25*25 image x16000frames 10*10 image * 250000 frames |
| Shutter Type | Electric Rolling Shutter |
| Computer Interface | USB3.0 |
| Built-in Image Buffer | 2GByte DDR3 Memory |
Cooling System | Dual Stage TEC cooler(-35C below ambient) |
Anti-Dew Heater | Yes |
Telescope Interface | M54/0.75 |
| Optic Window Type | AR+AR High Quality Multi-Layer Anti-Reflection Coating |
Back Focal Length | TBD |
Weigth | TBD |
