TO EXPLORE THE UNKNOWN UNIVERSE
Astronomical Camera QHY268PH M
Integration 25h 28'
Imaging telescope: TS-Optics 200mm/8″ ONTC f/4 Newtonian (carbon tube)
Mount: Orion Atlas AZ/EQ Pro
Guiding Cameras: QHYCCD QHY5L-II M
|Model||Retail Price （USD）|
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 QHY600 uses the latest SONY back-illuminated sensor, the IMX455, a full frame (35mm format) sensor with 3.76um pixels and native 16-bit A/D. This sensor is available in both monochrome and color versions. The QHY600 ends the days of non-16bit CMOS cameras and it ends the days non-full frame (and larger) monochrome CMOS cameras.
Equipped with a Sony IMX455, the QHY600 is a back-illuminated Scientific CMOS Camera with extremely low dark current (0.002e/p/s@-20C) using SONY’s Exmor BSI CMOS technology. QHY600 is also a zero amplifer glow camera.
The QHY600 has only one electron of read noise at high gain and full resolution and 4FPS readout speed. One electron of read noise means the camera can achieve a SNR>3 at only 4 to 6 photons. This is perfect performance when conditions are photon limited, i.e., short exposures, narrow band imaging, etc., making this large area sensor ideal for sky surveys, time domain astronomy, fluorescence imaging, DNA sequencing and microscopy.
In order to provide smooth uninterrupted data transfer of the entire 60MP sensor at high speed, the QHY600 has 2GB 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. For example, the QHY600 sensor produces about 120MB of data per frame. The data band-width is also increased from the original 16-bits to the current 32-bits. Transferring such a large file sizes necessarily requires the camera to have sufficient memory. The QHY600 has adopted a large-capacity memory of up to 2GB. 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.
Another advantage is that when using some computers that do not have fast processors or have poor support for USB 3.0, the computer can’t transfer high-speed data well, and the data is often lost. The DDR can buffer a lot of image data and send it to the computer. Even if the USB 3.0 transmission frequently gets suspended, it will ensure that data is not lost. There are options in SharpCap to turn DDR buffering on or off. The current version of the ASCOM driver works in DDR mode.
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.
BSI: One benefit of the back-illuminated CMOS structure is improved full well capacity. This is particularly helpful for sensors with small pixels. In a typical front-illuminated sensor, photons from the target entering the photosensitive layer of the sensor must first pass through the metal wiring that is embedded just above the photosensitive layer. The wiring structure reflects some of the photons and reduces the efficiency of the sensor. 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.
Anti-Dew Technology: 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.
Cooling: In addition to dual stage TE cooling, QHYCCD implements proprietary technology in hardware to control the dark current noise.
QHY600 Series have mutiple models which covers both photographic and scientific using. Below list different types of QHY600 PH (photographic) series:
QHY600PH : Standard version for amateur astrographers;
QHY600PH SBFL : it has shorter back focal length compared with other PH types;
QHY600PH L : a Lite, shorter and cheaper version.
QHY600PH-SBFL (Short back-focal length version) is specially designed for DSLR lens users or those who has special requirment of short back focal length. This version has a special front part version which has 14mm B.F.L only*. The front part includes six M2.5 screw holes arranged on a 80mm diameter roundness. QHY600 SBFL can easily match Canon/Nikon lens, even with filter wheel.
QHY600 Short Back-focus version supports CAA function, too. However, each QHY camera guarantees the right center angle with professional devices before the sale. So please do not adjust CAA unless there’s a problem at the front of the cam, like telescope adapters.
On the side of this adapter there is a 4mm hole to connect air pump through plastic pipe in case of the dewing glass when necessary.
1. QHY600L only has mono version.
2. The body length becomes shorter, which is about 112mm, and its price is lowered compared with QHY600 PH.
3. The Built-in DDR3 Buffer (memory storage) is adjusted to 1GB compared to 2GB of QHY600PH/Pro. Other specifications of QHY600L keep the same with QHY600PH except the body length and weight.
|Model||QHY600PH (Photographic Version)
QHY600PH SBFL (Short Back Focal Length Version)
QHY600PH L (Lite Version)
|CMOS Sensor||SONY IMX455|
|Mono/Color||Both Available (while Mono only with QHY600PH-L)|
|Pixel Size||3.76um x 3.76um|
|Effective Pixel Area||9576*6388
（9600*6422 with overscan and optically black area)
|Effective Pixels||61.17 Megapixels
|Sensor Size||Full Frame 36mm x 24mm|
|A/D Sample Depth
|16-bit (0-65535 levels) at 1X1 binning
18-bit at 2X2, 19-bit at 3X3, 20-bit at 4X4 software binning
*QHY600 uses the software digital binning for 2*2binning. With digital sum, 2*2binning will be four 16-bit summed then it is 18-bit.
|Full Well Capacity (1×1, 2×2, 3×3)||Standard Mode
>51ke- / >204ke- / >408ke-
Super Full Well Mode
>80ke- / >320ke- / >720ke-
|Full Frame Rate||USB3.0 Port Image Transfer Speed
Full Frame Size: 4.0FPS (8-bit output)
Full Frame Size: 2.5FPS (16-bit output)
7.2FPS at 9600×3194, 22.5FPS at 9600×1080, 28FPS at 9600×768, 47FPS at 9600×480, 160FPS at 9600×100,
Fiber Port Image Transfer Speed (QHY600Pro only)
Full Frame Size: 4.0FPS (16-bit output)
|Readout Noise||1.0e- to 3.7e- (Standard Mode)|
|Dark Current||0.0022e-/p/s @ -20C 0.0046e-/p/s @ -10C|
|Exposure Time Range||40us – 3600sec|
|Unity Gain*||25 (Extended Full Well Mode) *
*With the improvement of the CMOS technology, the 16bit CMOS camera has been released, like QHY600/268/411/461. For these cameras, even in lowest gain it has beyond the requirement of unit gain (less than 1e/ADU due to sufficient samples) So you can directly set gain 0 as start. Please note QHY600/268C/411/461 has extend full well mode. In this mode you still need to find out the unit gain position.
|Amp Control||Zero Amplifer Glow|
|Firmware/FPGA remote Upgrade||Supported. Via Camera USB Port|
|Shutter Type||Electric Rolling Shutter|
|Built-in Image Buffer||DDR3 memory
PH & PH SBFL ver.: 2GBytes（16Gbit）
|Hardware Frame Sequence Number||Supported|
|Cooling System||Dual Stage TEC cooler:
– Long exposures (> 1 second) typically -35C below ambient
– Short exposure (< 1second) high FPS, typically -30C below ambient（Test temperature +20°）
|Optic Window Type||AR+AR High Quality Multi-Layer Anti-Reflection Coating|
|Back Focal Length||QHY600PH&QHYPH-L: 17.5mm+6mm (±0.2)
*The BFL Consumed equals 12.5mm when connecting QHYCFW. About the defination of “BFL Comsumed” and our adapter system please view: https://www.qhyccd.com/adapters/
|Weigth||PH Version: 850g
Lite Version: 790g
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 QHY600 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.
QHY600 Performance Curves in 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.
QHY600 Performance Curves in 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.
QHY600 Performance Curves in Readout Mode #2 (Super 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 QHY600 can output the whole active area of the sensor, including the optically black pixels and the overscan area. The total image size including the optically black area area is 9600 x 6422 pixels. The optically black area is on the left of the image and the overscan area is on bottom of the image.
The difference of optically black area and overscan area is that the optically black area includes the dark current during a long exposure while the overscan area does not include the dark current during an exposure.
Neither the optically black area nor the overscan area respond to light, so they are regarded as the “non-effective” area of the sensor.
In the bottom of the overscan area you may find some vertical series of dots in single frame that can become vertical lines after stacking. One of the reasons for this is that the FPN calibration results represented in the overscan area can’t be found in the effective image area.
The following picture is the left bottom corner of a 300 second dark image. You can see these dots in the overscan area. The optically black level area and overscan area are usually used for precise calibration of an image and for calibration of an image without using a bias frame or dark frame, or for some scientific applications. Because the optically black and overscan areas are not part of the effective image area, QHYCCD does not guarantee the signal quality in these areas. If you do not use these areas, you can select the option “Ignore overscan area” in the ASCOM driver or select a ROI of effective area in SharpCAP.
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.
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.
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.
First there’s no doubt that 2-inch filters are large enough to cover the whole sensor area, but they’re not cheap enough for everyone. With a rough estimate, we think 36mm filter can be matched with scopes whose focal ratio are smaller than f/5 (f/4 worths a try, too). However, if your scope has a large focal ratio like f/2.8, we suggest you think carefully before using 36mm filters.
|Model||BFL Consumed||Filters Supported|
2inch mounted/50mm unmounted
Note: Adapter Kits B1 is provided FOR FREE with each QHY268M model. B1,B2,B3,are suited for QHY268M; Adapter Kits D1 is provided FOR FREE with each QHY268C model. D1,D2,D3,are suited for QHY268C.
B1: Connecting MPCC that requires 55mm BFL and M48 interface to Camera with CFWL and OAG
B1: Connecting MPCC that requires 55mm BFL and M48 interface to Camera with CFW3M-US Only
B1: Connecting MPCC that requires 55mm BFL and M48 interface to Camera with CFWM-US and OAG
Generally speaking, there’s no need for an OSC (one shot colored) camera to match filter wheel. If there’s any special needs, please refer to mono cam combos and choose the corresponding filter wheel. All OSC cams use OAG M if needed.
*About IR-Cut filter：
The sealing glass of QHY OSC cameras whose format are above APS-C is AR glass instead of IR/Cut filter. That’s because when the sensor size is bigger, if IR/Cut is closed to sensor, it’s easy to cause haloing effect on image. We use IR/Cut filter as sealing glass on 4/3 format cameras or below, like 163C, 183C; as for big sensor OSC cams, such as 268C, 367C, we provide a special adapter for fixing 2-inch IR/Cut filter at a farther position from the sensor, or users can fix the filter inside the default T mount.
All-In-One Pack （Driver, SDK and Software) for WINDOWS supports all QHYCCD USB3.0 devices only except PoleMaster and some discontinued CCD cameras. Please go to https://www.qhyccd.com/download/ and install it.
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.
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 a planetary/guiding camera, 12V power is not needed.
Note: We recommend 64-bit Software if possible, like SharpCAP x64 , N.I.N.A x64. etc., especially when you’re using 16bit cameras like QHY600.
EZCAP_QT is software developed by QHYCCD. This software has basic capture functions for QHYCCD deep sky cameras.
Run EZCAP_QT. Click “Connect” in Menu -> Camera. If the camera is successfully connected, the title line of EZCAP_QT will display the camera firmware version and the camera ID as shown below.
Click “Temperature Control” in “Camera Settings” to set the temperature of the CMOS sensor. You can turn on “Auto” to set the target temperature. For example, here we set the target temperature to -10C. The temperature of the CMOS sensor will drop quickly to this temperature (approximately 2-3 minutes). If you want to turn off cooling, you can choose Stop. If you just want to set the TEC power but not the temperature. You can select “Manual” and then set the percentage of the TEC power.
You can use the “preview tab” to preview and use the focus tool to focus. Then use the “capture tab” to capture the image.
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.
With ASCOM drivers, you can use the device with many software packages that support the ASCOM standard. We will use Maxim DL below as an example, but a similar procedure is used for The SkyX and other software packages supporting ASCOM.
First make sure you have not only loaded the ASCOM drivers but that you have also downloaded and installed the ASCOM platform from ASCOM. After both the drivers and platform are installed, start MAXIMDL. Follow the instructions shown below to finish the setup. Then Click Connect in and enter the software.
QHYCCD BroadCast WDM Camera is a broadcast driver that supports QHYCCD cameras with video broadcast function, which can meet the needs of customers to send video images to other target software. For example, use sharpcap to connect a WDM-enabled camera, and the sharpcap display video image can be sent to other WDM-supported software for display, which is suitable for video online broadcast applications.
The installation process is over, right-click the computer to find the device manager, and check that the image device name is QHYCCD BroadCast WDM Camera, which means the installation is successful.
HANDYAVI test effect chart:
UFOCAPTURE test renderings:
How to avoid the camera hanging?
If your camera hangs (stops downloading images and does not respond to commands) it may be caused by a number of things. Check the following:
1. In some computers with a VIA chipset and some types of motherboards, running the camera with SharpCap will not produce an image. But in ASCOM it works well. In this case, you need enable the DDR buffer of the camera.
2. Is there a leak for your mount or computer? If so, the leaking current may be transferred from computer to the camera via the GND. This may affect the USB transfer and cause data packet loss, hanging the camera. In this case you need to make sure that the computer and mount are well grounded.
3. Is the USB port voltage sufficient? The voltage of some computers’ USB ports is sometimes less than +5V. This may cause the camera to hang. In this case you can use a powered USB 3.0 HUB to connect camera, which will ensure that the camera gets +5V power.
4. Is your CPU utilization is too high? If your computer’s CPU utilization is too high, it will cause many frames to be lost and may cause the camera to hang. You can change the USB
traffic value to reduce the FPS and get more stable video transfer.
5. Is the USB cable connection is secure enough? Sometimes a connection issue with the USB cable to camera or USB cable to computer will cause some signal loss and may cause the camera to hang, particularly when you move the cables. In this case you can try to add a little silicon oil into the USB connector and socket. This can make the connection more stable.
6. Avoid the static electricity. Static electricity from the human body can cause the camera to hang. To ground yourself, touch the external metal case of the computer to discharge any static electricity before touching the camera.
7. Are you using the front USB port on your computer? The USB port on the front of some computers is not adequate for high-speed transfer because it is connected to mainboard by a cable which weakens the signal integrity. If you find that the camera always hangs when using the front USB port, try using a USB port on the rear panel of the computer instead. This will connect the camera to the chipset on the mainboard directly.
8. When the USB selective pause function is enabled in the system, it may cause the camera to hang during long hours of work. Follow the steps below to turn off this option. Windows power setting steps: 1. Click “Start button” and click “Settings”. 2. Click “Power and Sleep”, and click “Other Power Settings”. 3. Click “Change Power Plan”. 4. Click “Change advanced power settings”. 5. By default, the “USB Selective Suspend” function is enabled. (This may cause the image to freeze, the frame rate too become low, the video to become unsmooth, the image fail to refresh, and so on.) 6. Disable this function.
9. When you encounter a situation where the camera cannot output the usual frame rate after updating Sharpcap software, please download the All-In-One installation package and select the Sharpcap option during installation. The installation package will automatically update the QHY SDK in Sharpcap. Restart the sharpcap software after completion.
Image misalignment due to USB data transmission errors
What is happening here can be caused by USB communication problems or external interference problems. The data of the USB image packet being transmitted is wrong and cannot pass the CRC check, so the SDK judges it as a USB transmission error. The SDK will repair communication errors to avoid crashes, but this packet of data will also be lost. To trouble shoot this type of issue, note the following:
(1) Communication quality problems caused by USB cable damage or poor USB contact: The solution is to replace the USB cable, and check the connection of the USB cable to the computer and whether the connection between the USB cable and the camera is too loose.
(2) Some HUBs with mismatched signals may cause such problems. Connect directly or replace to another type of HUB. (It is recommended to use active HUB)
(3) The communication is experiencing interference problem caused by noise or voltage leakage of the AC adapter. Check whether the AC adapter of each device in the system is well grounded.
(4) You may be using an SDK and firmware that do not match. Download the latest installation package ( All-In-One package), or request QHYCCD technology Support for remote assistance.
Shooting flat field is the difference between light and dark above and below the image FAQ:
This situation is caused by the rolling shutter effect, which is easy to encounter when shooting short exposures. Increasing the exposure time can avoid this difference. It is recommended to use an exposure time greater than 1 second for flat-field frame shooting.
To avoid the problem of unreliable USB connection or port damage caused by leakage of computer or 220V to 12V adapter
Some computers or 220V to 12V adapters have leakage currents. If they are not well grounded, a high voltage is formed between the ground (metal case) of the USB interface and the ground (metal case) of the power supply line. If the USB and power supply wires are in good contact with the camera, the device can operate normally due to the formation of a common ground at the camera.
However, the common ground formed at the camera is very dangerous. On the one hand, it is easy to cause the USB connection to be unreliable, and the USB connection is often lost during use, and on the other hand, there is a risk of potentially damaging the port. Therefore, make sure the computer and adapter are well grounded before putting the device into service.
You can use the multimeter’s AC voltage file to detect if there is any leakage between the computer and the adapter. The method is not to connect the camera first, one meter is connected to the metal case of the USB plug, and the other meter is connected to the negative pole of the DC output plug of the power adapter (generally inside and outside negative). If the voltage between the two is small, there is no leakage or a good ground has been achieved through the ground of the power plug. If there is a voltage of several V to several tens of V, there is leakage and there is no good grounding. Need to check if the 220V power plug can provide a good ground.
If there is no way to avoid it, you need to use a separate wire to connect the ground of the computer (usually connected to the metal case) and the negative pole of the 220V to 12V adapter to achieve common ground.
The CMOS sensor is located in the CMOS chamber. 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 is moisture in the CMOS chamber that causes the sensor glass to fog, you can connect the silica gel tube to this hole for drying the chamber.
Place an effective silica gel desiccant in the silica tube make sure there is some cotton inside to prevent the silica gel from entering the CMOS chamber.
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.
If the ambient humidity is very high, the optical window of the CMOS chamber may have condensation problems. The QHY600 has a built-in heating plate to heat it to prevent fogging. In most cases, it is very effective. However, If fogging still persists, try the following:
1. Avoid directing the camera towards the ground. The density of cold air is greater than the density 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. Increase the temperature of the CMOS sensor. You can increase the temperature of the CMOS sensor slightly to prevent fogging of the glass.
3. Check if the heating plate is working. If the heating plate is not working, the glass will be very easy to fog. Normally, the temperature of the heating plate can reach 65-70 °C in the environment of 25 °C. If it does not reach this heat, it may be because the heating plate is damaged, you can contact us to replace the heating plate.
You should 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.
|600M/C||25 (Extended Full Well Mode) *|
|268M/C||30 (Extended Full Well Mode) *|
|294Pro||1600 (11MP Mode)
2600 (47MP Mode)
|410C||90 (Low gain)
40 (High gain)
*With the improvement of the CMOS technology, the 16bit CMOS camera has been released, like QHY600/268/411/461. For these cameras, even in lowest gain it has beyond the requirement of unit gain (less than 1e/ADU due to sufficient samples) So you can directly set gain0 as start. Please note QHY600/268C/411/461 has extend full well mode. In this mode you still need to find out the unit gain position.
For beginner, we recommend that you set the gain to “unit-gain”. Unit-gain is the gain when system gain is 1 (1e/ADU). This number is shown in the table above, like the unit-gain of QHY168C is 10. In fact, increasing or decreasing a bit doesn’t make a big difference.
You could increase or decrease Gain according to the condition. For example, if your optical system is fast, like F2.2 to F5, or long exposure for more than 5 minutes without narrowband filters, then you can decrease GAIN to achieve a higher dynamic range and make better use of full well capacity. By doing so you can avoid overexposure.
If you use narrowband filter on a slow optical system like F6 to F10, or short exposure time, the amount of photons received will be less. In this case you can increase GAIN to make better use of characteristics of low read-out noise in high GAIN value.
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.
As you can see, the histogram distribution is a peak-like curve. By changing the OFFSET value, this curve will move left or right. We must guarantee the range of the whole curve is greater than 0, and it cannot be chopped off at the end. At the same time, we need to keep a bit of residue on the left side, just over 0 a bit. 100 to couple hundreds ADU are all okay. Don’t be too huge, however.
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 st low GAIN is not suitable for high GAIN, because the curve is very likely to be chopped off.
For those CMOS less than native 16-bits, the AD sampling accuracy doesn’t match perfectly with the full well capacity. At low GAIN level, the system gain will be couple electrons per ADU. The camera loses the ability to distinguish the strength of the signal because of such sampling error.
When GAIN increases, the system gain will decrease. However, increasing GAIN will limit the full charge of the well. If the system gain is 1 for a 12bit CMOS camera, the pixel will be saturated at only 4096 electrons (full well). Some bright stars will be easily saturated. This problem goes worse under fast optical system or long exposure. Over saturated objects cannot be fixed during post processing (unless you shrink stars, like in PixInsight). Also, the color saturation of the star will be affected. As result, the stars will be huge and white washed. We should decrease the gain value in this case, to gain a higher full well capacity.
Under long exposure or using fast optical system, the pixel will receive more photons. The variation of quantized noise from the photon which you can consider as natural dithering of the light intensity, will be greater than the “noise” from the sampling error. Therefore, the effect of the sampling error will diminish. By averaging multiple exposures, this will compensate the lack of depth of the picture because of the sampling error.
If the number of received photons is limited, like using narrowband filters or short exposures, we can increase the GAIN value. It is because the stars will not be easily saturated. At the same time, we limit the noise from the background cosmic radiation. Under this condition, the readout noise and quantized noise are the major factors that affect the ability to distinguish dim light or objects. By increasing the GAIN value in order to decrease the readout noise and quantized noise from sampling error, this would greatly increase the signal to noise ratio.
|Cooled CMOS Camera||Bayer|
|Planetary and Guiding||Bayer|
|Cooled CCD Camera||Bayer|
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: