TO EXPLORE THE UNKNOWN UNIVERSE
NGC 6888 and bubble soap nebula
APOD 2023 Sep 04
Imaging Camera QHY268M
Integration 44 hours 30 min
Telescope: Askar FRA600
Mount: iOptron CEM40
1.Since January 2023, the top part of QHY268C will change to the shorter one just like that of 268M. In fact, you can get the “SBFL(shorter back focal length)” version of 268C right now. The previous 268c has a back focal length of 17.5mm, and since it cannot connect to the scope without CAA, so it’s actual BFL is 17.5mm+6mm=23.5mm. Now after the change, 268C’s BFL will be shortened to 14.5mm, which provides more space for a filter wheel drawer, or an electric CAA, or DSLR Lens, etc.
2.Since Jun 2023, The position of the heating board of the QHY268PH Series will be raised by about 5mm, which will decrease the likelihood of fogging. This change will not affect the back focal length calculations or any other function. The mono cameras will use the same adapter kit as before. The color cameras will have a different adapter kit (G1) as a standard accessory which will be supplied with the camera. This change will be applied first to the QHY268M-PH as of this announcement and then to the color camera from September 1, 2023.
【The Andromeda Galaxy】NASA APOD
Author: Abdullah Al-Harbi
Imaging Telescopes Or Lenses: Askar 600
Imaging Cameras: QHY 268M
Mounts: CEM 40
Filters: Chroma 36mm LRGB Ha
G 300s*34B 300s
Total integration 15.5 hours
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.
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.
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)
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.
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 PH||QHY268C PH|
|CMOS Sensor||SONY IMX571||SONY IMX571|
|Pixel Size||3.76um x 3.76um|
|Effective Pixel Area||6280*4210 (includes the optically black area and overscan area)|
|A/D Sample Depth
|Native 16-bit (0-65535 greyscale) A/D|
|Full Well Capacity (1×1, 2×2, 3×3)||51ke-
75ke- or above in extended full well mode
|Full Frame Rate||USB3.0 Port:
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
|Readout Noise||1.1e- High Gain,
3.5e- Low Gain
(5.3e- to 7.4e- in extended full well mode)
|Dark Current||-20℃，0.0005e /pixel/sec
|Exposure Time Range||30us-3600sec|
|Recommend Gain*||30 (PH Mode， or Extended Full Well Mode)
56 (High Gain Mode)
*With the improvement of the CMOS technology, For these 16bit CMOS cameras, even in the lowest gain it has beyond the requirement of unit gain (less than 1e/ADU due to sufficient samples).
Learn more at the “Readout Modes” part of this page.
|Amp Control||Zero Amplifer Glow|
|Firmware/FPGA remote Upgrade||Fully support via Camera USB port|
|Shutter Type||Electronic Shutter|
|Built-in Image Buffer||1GByte DDR3 Memory|
|Cooling System||Two-stage TEC cooler
Less than 1S lower than ambient temperature -30℃ in continuous mode
More than 1S continuous mode or lower than ambient temperature -35℃ in single frame mode
（Test temperature +20℃）
|Optic Window Type||AR+AR High Quality Multi-Layer Anti-Reflection Coating|
|Telescope Interface||Support M54 or M48 (Combined with adapters )||Support M54 or M48 (Combined with adapters )|
|Back Focal Length||14.5mm（±0.2）||14.5mm（±0.2）*
*Since 2023, the top part of QHY268C is the same as 268M.
|Weigth||About 810g||About 810g|
The New Combo B1 is designed to be more flexible to achieve multiple output specifications. Since June 2023, we are adding a 5mm spacer with M54 threads into Adapter kit B1. This addition gives the user a choice of terminating the output in either M48 or M54 threads. You can get 55/56mm BFL with M48/M54 threads according to your needs. Since are standard accessories included with the camera, this addition has no affect on the price.
55mm M48/M54 are suitable for standard flatteners and multiple purpose coma correctors (MPCC), while 56mm M54 threads are common for Takahashi reflectors.
The camera requires an input voltage between 11V and 13.8V. If the input voltage is too low the camera will stop functioning or it may reboot when the TEC power percent is high, causing a drain on the power. Therefore, please make sure the input voltage arrived to the camera is adequate. 12V is the best but please note that a 12V cable that is very long or a cable with small conductor wire may exhibit enough resistance to cause a voltage drop between the power supply and the camera. The formular is: V(drop) = I * R (cable). It is advised that a very long 12V power cable not be used. It is better to place the 12V AC adapter closer to the camera.
First connect the 12V power supply, then connect the camera to your computer via the USB3.0 cable. Make sure the camera is plugged in before connecting the camera to the computer, otherwise the camera will not be recognized. When you connect the camera for the first time, the system discovers the new device and looks for drivers for it. You can skip the online search step by clicking “Skip obtaining the driver software from Windows Update” and the computer will automatically find the driver locally and install it. If we take the 5IIISeries driver as an example (shown below), after the driver software is successfully installed, you will see QHY5IIISeries_IO in the device manager.
Please note that the input voltage cannot be lower than 11.5v, otherwise the device will be unable to work normally.
All-in-one Pack supports most QHYCCD models only except PoleMaster and several discontinued CCD cameras.
Download Page: https://www.qhyccd.com/download/
Video Tutorial: https://www.youtube.com/embed/mZDxIK0GZRc?start=1
Before using software, make sure you have connected the cooling camera to the 12V power supply and connected it to the computer with a USB3.0 data cable. If it’s an uncooled camera, 12V power is not needed. We recommend 64-bit Software, like SharpCAP x64 , N.I.N.A x64. etc., especially when you’re using 16bit cameras.
In NINA, you can select the device to connect to QHY Camera directly without ASCOM driver.
If connecting to the camera via ASCOM is desired, first make sure you have installed both the QHYCCD ASCOM Drivers and ASCOM Platform. Then you would select the appropriate camera driver under the ASCOM section. Then click the Connect icon. Here we take NINA as an example, but it’s similar to other software packages supporting ASCOM, like MaxDL, The SkyX, etc.
Launch SharpCap. If the software and drivers mentioned above are installed successfully, the video image will appear automatically about 3 seconds after the software loads. You will also see the frame rate in the lower left corner of the software window as shown below.
If you have already started the SharpCap software before connecting the camera, in order to open the camera, click on the “camera” in the menu bar and then select the device.
Offset adjustment. When you completely block the camera (i.e., like taking a dark frame) you may find that the image is not really zero. Sometimes this will reduce the quality of the image contrast. You can get a better dark field by adjusting the offset. You can confirm this by opening the histogram as indicated in the figure below.
If you want to enter the 16-bit image mode, select the “RAW16” mode.
By selecting the “LX” mode you can expand the exposure setting range and take long exposures.
After cooling devices connected to the 12V power supply, the temperature control circuit will be activated. You can control the CMOS temperature by adjusting the settings in the figure below. Basically, you can control the temperature of CMOS by either adjusting “Cooler Power” or clicking “Auto” and setting “Target Temperature”. You can also see the CMOS temperature at the lower-left corner of the software window.
Now with the improvement of the CMOS technology, the 16bit CMOS cameras like QHY600/268/411/461, can be directly set gain 0 under default Photographic DSO mode. Even in lowest gain（zero） they’re beyond the requirement (less than 1e/ADU due to sufficient samples).
However, when you use QHY600/268/411/461 under Extended Fullwell Mode, we recommend their unit gain as default.
There is no fixed “best value” for OFFSET. To set OFFSET, you should take the bias frame and dark frame at a certain GAIN value, then check the histogram of the frames.
The histogram distribution is a peak-like curve. While changing the OFFSET value, the histogram will move left or right. We need to guarantee the range of the whole curve won’t be chopped off at the end. At the same time, we need to keep a little residue on the left side, just over 0 a bit.
Pay attention that under different GAIN values, the width of this peak varies. The higher the GAIN is, the wider the distribution will be. So OFFSET value at low GAIN is not suitable for high GAIN because the curve is easily to be chopped off.
UVLO（Under Voltage Locking), is primarily intended to protect the electronic device from damage caused by abnormally low voltages. Now only QHY600, QHY268, QHY410, QHY411, QHY461, QHY533 cameras have UVLO Protection.
UVLO warning execution
After a warning is given, the camera firmware will automatically turn off the cooler and will turn on the camera’s TEC protection mode. After the camera is reconnected, it will always work in TEC protection mode (maximum power cooler power will be limited to 70%). Since many times the voltage shortage is caused by the high resistance of the power supply cable itself, resulting in a large voltage drop at high currents, the voltage will usually rise after the power is limited. But limiting the power will affect the cooling temperature difference. Therefore, it is recommended that users first check the power supply cable to solve the problem of excessive resistance of the power supply cable.
If the user has solved the problem of insufficient supply voltage, the TEC protection mode can be removed through the menu of EZCAP_QT.
How to improve the power supply?
How to clear the TEC protection status triggered by UVLO?
Once a UVLO event occurs, the camera will automatically memorize it and will work in a protected mode at a maximum of 70% power after reconnection. This memory can be erased as follows:
After you find the system error, you need to turn off the device and check the power supply. After inspecting the problem, open the ezcap software and select “Camera Settings” – “Preferences” – “Reset Flash Code” to reset the error status.
Why does the warning appear even though the power supply voltage is 12 V?
|Cooled CMOS Camera||Bayer|
|Cooled CCD Camera||Bayer|
|Planetary and Guiding||Bayer|
Now the ratio R”:G”=(R+bias)/(2R+bias) and it is not equ to 1:2. It shows the bias will effect the true value of the R:G. And the ratio of R:G will arious when the image light changed. It is hardly to correct with a fixed ratio.
But for DSO capture, You should keep the offset above zero and avoid the background is cut off. A background from 1000-5000 is a good value(16bit mode) for DSO imaging.
Added functions related to BURST mode in SDK. Currently, cameras that support Burst function include QHY600, QHY411, QHY461, QHY268, QHY6060, QHY4040, QHY4040PRO, QHY2020, QHY42PRO, QHY183A
This mode is a sub-mode of continuous mode. This function can only be used in continuous mode. When this function is enabled, the camera will stop outputting image data, and the software frame rate will be reduced to 0. At this time, send relevant commands to the camera, and the camera will Output the image data with the specified frame number according to the settings, for example, set Start End to 1 6, the camera will output the image data with the frame number 2 3 4 5 when receiving the command.
1. When using Burst mode in fiber mode, the first Burst shot will be one less. For example, if the start end is set to 1 6, the output of 2 3 4 5 is normal, but in fact, only 3 4 will be output during the first burst shot. 5, 2 will not be received, the second and subsequent shots can normally obtain Burst images 2 3 4 5. This problem will be fixed later.
2. QHY2020, QHY4040 found that the frame number that came out when the exposure time was short is [start+1,end-1] but the one that came out under long exposure was [start+2,end]
3. When the camera is just connected, if the set end value is relatively large, the camera will directly output the picture after entering the burst mode. Therefore, it is necessary to set the camera to enter the IDLE state and then set the start end and related burst operations.
The following is the usage of Burst mode related functions:
There is a hole in the side of the camera near the front plate that is normally plugged by a screw with an o-ring. If there’s moisture in the CMOS chamber that causes fog, you can connect the desiccant tube to this hole for drying. There would better be some cotton inside to prevent the desiccants from entering the CMOS chamber.
Please note that you may need to prepare desiccants yourself, because for most countries and regions desiccants are prohibited by air transport. Since QHY always deliver your goods by air, sorry that we can’t provide desiccants for you directly.
If you find dust on the CMOS sensor, you can first unscrew the front plate of the cam and then clean the CMOS sensor with a cleaning kit for SLR camera sensors. Because the CMOS sensor has an AR (or AR/IR) coating, you need to be careful when cleaning. This coating can scratch easily so you should not use excessive force when cleaning dust from its surface.
All QHY cooling cameras have built-in heating plates to prevent fogging. However, If the ambient humidity is very high, the optical window of the CMOS chamber may have condensation issues. Then try the following:
1. Avoid directing the camera towards the ground. The density of cold air is greater than of hot air. If the camera is facing down, cold air will be more accessible to the glass, causing it to cool down and fog.
2. Slightly increase the temperature of the CMOS sensor .
3. Check if the heating plate is normally working. If the heating plate is not working, the glass will be very easy to fog, the temperature of the heating plate can reach 65-70 °C in the environment of 25 °C. If it does not reach this, the heating plate may be damaged. Please contact us for maintenance.
Please avoid thermal shock during use. Thermal shock refers to the internal stress that the TE cooler has to withstand due to the thermal expansion and contraction when the temperature of the TEC suddenly rises or falls. Thermal shock may shorten the life of the TEC or even damage it.
Therefore, when you start using the TEC to adjust the CMOS temperature, you should gradually increase the TEC power rather than turning the TEC to maximum power. If the power of the TEC is high before disconnecting the power supply, you should also gradually reduce the power of the TEC and then disconnect the power supply.
Now the FAQ part has been intergrated into “QHYCCD Help Center“–Knowledge base
This is QHYCCD Help Center. Here you can:
Submit a Ticket: Describe the issue you met while you’re using them. Our technicans will reply you in 48 hours during working days. You don’t have to check the Ticket update everyday—they can receive email notifications and know if there’s any update.
Knowledge Base: Here lists some tips for using your gears, or solutions to issues that you may met. Help your self!
Support History: Check your ticket’s status.