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QHY268C Manual
2019 年 12 月 14 日
QHY268C Manual

This document is an online document. You may save this PDF file or print it out. QHYCCD reserves the right to change this user manual without prior notice.
Package Contents
please confirm that the package contains the following items:
USB3.0 cable(1.5m) 1 All version
Self-locking power cable 1 All version
Car power adapter 1 All version
Drying tube 1 All version
Desiccant 1 Note. From 2018 the China custom house prevent the delivery of the silicon gel to some country. So this item is may not included
Inspection report 1 All version
Driver download card 1 All version
QHY268C camera with center/tilt adjust ring 1 All version
0.5mm-13.5mm spacer with 6 holes 1 All version
M54-2inch 1 All version
12V AC power adapter and cable 1 Optional *. For this item. Some area of dealer may includes it some may not.


00 Important hint of using the camera
01 Software installation
02 Description of each interface
03 Using QHY268C in SharpCap
04 Using QHY268C in ASCOM
05 Using QHY268C in EZCAP_QT
06 Using QHY268C in N.I.N.A. - Nighttime Imaging 'N' Astronomy 
07 FAQ
08 Camera maintenance
09 Specifications
10 Mechanical size and back focal length
11 Version history

00 Important hint of using the camera

How to reboot the camera
QHY268C is designed as using the +12V to reboot the camera, Not using the disconnect/reconnect USB method. So if you want to reboot the camera, just shut down the +12V and then power on it.  This feature is very useful for the remotely obs. You can use a remotely controllable powersupply to reboot the camera. No need to consider how to do USB reconnecting in remotely conditions.

So please note that when you wanting to reboot the camera, just show down/power on the +12V, Not disconnect/reconnect the USB.

What is the readout mode of QHY268C?
The readout mode is the different CMOS drive timing and settings. Different read mode will have different performance like the different fullwell, different readout noise and different of other noise behaviour. Since different readmode has its advantages and disadvantages, so we allow user to set different readout mode. Currently both the ASCOM driver, SharpCAP support this options.  QHY268C has three readout mode currently.

Image Area Layout 
QHY268C can output the whole image with the optic black area and overscan area. The total image size includes the Optic black area is 6280*4210. The optic black area is on the left of the image and the overscan area is on bottom of the image. 

The different of optic black area and overscan area is that the optic black area includes the dark current during long exposure while the overscan area does not includes the dark current during exposure time.

Both optic black area and overscan area can not response to the light. So it is regards as the "Non-Effective" area of the sensor. 

In the Bottom of the overscan area. You may find some "vertical dot lines" in single frame and after stacking it will become some vertical lines, one explain of the reason of this is the "FPN calibraiton results” represented in the overcan area. In the effective image area you will not find this .

The following picture is the left bottom corner of a 300sec dark image. You can find these area.

The optic black area and overscan area is usually used for precise calibration and for the calibration without the bias frame and dark frame, or other scientific using. Due to it is an non-image area ,  QHYCCD does not guranttee the signal quality in the overscan area. If you do not use this area, you can select the option "ignore overscan area" in the ASCOM driver or select a ROI of effective area range in SharpCAP.

Input Voltage Requirement
The QHY268C requires the input voltage between 11V to 13.8V. If the input voltage is too low it will cause the camera not working or reboot if the TEC power percent is high. So please make sure the input voltage arrived to the camera is enough. The best is 12V. Please note there is the resistance for the 12V power cable. If the cable is very long, when in high power, the resistance will cause a voltage drop on this cable.  The formular is :    V(drop) = I * R (cable)  . We recommend that avoid to use a very long 12V power cable. You can put the 12V AC adatper more close to the camera.

Connect the 12V power supply to the QHY268C first, and then connect the QHY268C camera to your computer via the USB 3.0 data cable. Be sure to connect the QHY268C to a power source before connecting the camera to the computer, otherwise the camera will not recognize it. When connecting for the first time, the system will discover new devices and look for drivers for them. You can click "Skip to obtain driver software from Windows Update" to skip the online search step, and then the computer will automatically find and install the driver locally. After the driver software is successfully installed, you can see QHY5IIISeries_IO in the device manager, as shown in the figure below.

After you download and install the new driver, please unplug the USB data cable, and then re-plug it to make the new driver take effect.
02 Description of each interface
03 Using QHY268C in SharpCap
1. Connect the QHY268C to a 12V power supply and connect your QHY268C to your computer using a USB 3.0 data cable.
2. If you have activated the SharpCap software before connecting the camera, in order to open the camera, you can click on the camera in the menu bar and select QHY268C
3. Turn on SharpCap. If the software and driver mentioned above are successfully installed, the video image will appear automatically, and you can also see the frame rate in the lower left corner of the software, as shown in the figure below.

4. Offset adjustment. When you completely block the camera, you may find that the image is not really completely black. Sometimes this reduces 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. In addition, color camera adjustment of white balance also needs to be adjusted according to the histogram display.

5. By selecting “LX” mode, you can expand the exposure time range for long exposure. QHY268C is equipped with amplifier luminescence suppression circuit, which can avoid the luminescence generated by the amplifier during long exposure. 
A long-exposure image at -10 ° C, 20s exposure time.

6. After the QHY268C is connected to a 12V power supply, the temperature control circuit will start. You can control the temperature of the CMOS by adjusting the settings in the figure below.

There are two main ways to control the temperature, one is to adjust the Cooler Power, and the other is to set the Target Temperature. If you want to directly control the CMOS temperature by setting the target temperature, you should click “Auto” first and then set the target temperature by adjusting the slider.
Before using the cooling function, you should read the question "How to protect the refrigerator" in the FAQ to make better use of the cooling function.

QHY268C has added the Read MODE function, which is a new feature of the new QHY camera. Different readout modes have different driver timing, etc., and lead to different performance results. Each read mode has its advantages and disadvantages. QHY268C currently has three reading modes. (PhotoGraphic DSO, High Gain Mode, Extend Fullwell) QHYCCD may add more modes in the future. QHY ASCOM camera driver and SharpCAP software and the readout mode currently supported by NINA software. You can find the list box in the software. Set in SharpCap as follows:

04Using QHY268C in ASCOM
QHY268C can work on most software supporting ASCOM platform. Currently QHY268C only supports regular ASCOM connection, but does not support ASCOM VIDEO connection. It should be noted that QHY268C will always transmit the maximum bit depth to get the best DSO imaging performance. The format of the image is native 16bit.
1. First you need to confirm that both the ASCOM platform and the ASCOM driver have been successfully installed.
3. Follow the prompts below to complete the setup

You need to click Connect before shooting. After connecting the camera, click Cooler to set the cooling temperature and turn on the cooling.

Click Expose to enter the interface and click Start to shoot.

Because QHY268C is a color camera, the original image in MaximDL is black and white. You need to convert the color to color in the software.

QHY268C has added the Read MODE function. This function includes 3 modes: PhotoGraphic DSO, High Gain Mode, and Extend Fullwell. Set in MaximDL as follows:


05Using QHY268C in EZCAP_QT
EZCAP_QT is a software developed by QHYCCD. For QHYCCD deep space cameras, it has basic shooting functions. You can download and use it in the previous link.
1. Install the EZCAP_QT software;
2. Connect 12V power to QHY268C first, then connect QHY268C camera to your computer via USB3.0 data cable.
3. Start EZCAP_QT and click “Connect” in Menu-> Camera. If the camera is successfully connected, the title of the EZCAP_QT software will display the camera's firmware version and camera ID, as shown in the figure below;

Language can be switched in Language.
4. 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 soon drop to this temperature (about 2-3 minutes). If you want to turn off cooling, you can select "Stop". If you only want to set the cooling power and not the temperature, you can set the power percentage.

5. You can use the preview tab to preview and use the focus tool to focus. Then use the Capture tab to capture the image.
First adjust an approximate focal length in Previewzh, double-click an area in the image to select the area, and enter Focus to focus.


6. There is an image task planner in EZCAP_QT, you can take a series of images with reference to the table below.

06 N.I.N.A. - Nighttime Imaging 'N' AstronomyUsed in QHY268C
NINA has two connection methods, one is directly connected through QHY plug-in, and the other is connected through ASCOM.
(Refer to MaximDL for ASCOM connection)
Direct connection through the QHY plugin requires replacing the latest qhyccd.dll in the software installation directory
Connect the QHY268C to a 12V power supply and connect your QHY268C to your computer using a USB 3.0 data cable.
Open N.I.N.A.-Nighttime Imaging 'N' Astronomy. QHY268C now click to connect in Camera,
Turn on cooling after connecting.

Setting the exposure time to take an image

Set shooting plan

08 FAQ
1. How to avoid camera stuck?
If the camera is stuck all the time, it may be caused by a variety of reasons, you can follow the prompts below to check.
1) Whether your computer is configured with a VIA chipset or some type of motherboard, it does not appear on SharpCap (but works on ASCOM). In this case, you need to turn on the camera's DDR buffer.
2) Is your computer and equatorial device leaking? This may cause leakage current to be transferred from the computer to the camera through GND. This may affect USB transmission, loss of data packets, and camera jam. You need to make sure the computer and the equatorial mount are well grounded.
3) Is the voltage of the USB interface high enough? Some computers have a USB interface voltage of less than 5V. This may cause the camera to get stuck. In this case, you can choose to connect the computer to the camera by using the USB3.0 Hub with power supply, which ensures that the camera gets 5V.
4) Is the CPU usage too high? If the CPU usage is too high, it will cause many frames to be lost and the camera will be stuck. You can increase the USB traffic value to lower the FPS for more stable image transmission.
5) Is the USB cable securely connected? Sometimes problems with the connection of the camera to the USB cable and problems with the connection of the computer to the USB cable can result in loss of signal and jamming of the camera. Especially when the USB cable is moving. In this case, you can try applying some silicone oil to the USB connector and the socket section. This will make the USB connection more stable.
6) Avoid static electricity. Sometimes static electricity carried on the human body can cause the camera to become stuck. Before touching the camera, you can touch the computer case to discharge static electricity.
7) Some computers have a front USB interface that is not suitable for high-speed data transmission (because they are connected to the motherboard through a cable, which makes signal integrity worse). If you find that the camera is stuck when the front USB port is in use, you can try connecting the camera to its rear USB port (they are directly connected to the motherboard's chipset).
8) When the USB selective pause function is turned on in the system, it will cause the camera to freeze 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, which will cause the image to freeze, the frame rate is low, the video is not smooth, the image is not refreshed, and so on. We need to disable this feature. 6. Disable this function.

2. How to clean the CMOS sensor and optical window?
If you find dust on the CMOS sensor, you can first unscrew the front half of the QHY268C and then clean the CMOS sensor with the cleaning kit for the SLR camera sensor. Because the QHY268C's CMOS sensor has an AR coating, care must be taken during the cleaning process.
Care must be taken during the cleaning process. You can also use the SLR cleaning tool or lens paper for cleaning. Note that the force should not be too large, because the coating is very fragile and can be easily scratched.

3. What is the camera's built-in DDR buffer? What are its advantages?
The QHY268C has a built-in 1GB(8Gbit)/ 2GB(16Gbit)DDR3 image buffer. It has two advantages:
It can buffer the entire image to avoid loss during USB transmission. Because the CMOS sensor will continue to be exposed as soon as it starts working, the image will be output, and it will not stop. However, the computer will pause the USB transfer because of the multitasking characteristics of the operating system. If the pause time is too long, the buffer with small storage capacity in the USB will be full, resulting in the loss of the upcoming data. It is also possible to cause partial data loss of one frame to form a bad frame. For short exposures, this may not cause too much problems, but for long exposures, this means losing a long exposure image. The 1GB(8Gbit)/ 2GB(16Gbit)DDR3 buffer solves this problem by storing and transmitting the entire frame of images. Even if the USB transfer is paused for a long time, no data will be lost.
Another advantage is that when using some computers that are not running fast or have poor support for USB3.0, it will make the video images more delicate and smooth. These computers can't transfer high-speed data well, and the data will often be lost. With DDR. A buffer that buffers a lot of image data and sends it to the computer. Even if USB 3.0 frequently suspends transmission, 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 has been working in DDR mode.

4. How to protect the refrigerator?
The QHY268C's chiller can achieve an ambient temperature difference of nearly 35 °C. You should avoid thermal shock during use. The so-called thermal shock refers to the internal strong stress that the refrigerator has to withstand due to the thermal expansion and contraction principle when the temperature of the refrigerator suddenly rises or falls. The thermal shock of the distance shortens the life of the refrigerator. Even completely damage the refrigerator.
Therefore, when you start using the chiller to adjust the CMOS temperature, you should avoid turning the chiller to maximum power and gradually increase the chiller power. If the power of the chiller is high before disconnecting the power supply, you should also gradually reduce the power of the chiller and then disconnect the power supply.

5. Horizontal banding Optimize
It is a common behavior for CMOS sensor which contains some horizontal banding. Normally speaking the random horizontal banding can be removed with multiple frame stacking so it will not effect the image. The periodic horizontal banding can not be removed with stacking so it will bring some problem for the image.   For QHY268C, by adjust the USB traffic in both Single Frame mode or Live Frame mode, you can adjust the frequency point 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 value

After Adjust the USB_Traffic to avoid the periodic horizontal noise

08 Camera Maintenance

Dry camera CMOS cavity
The CMOS sensor is located in the CMOS cavity. There is a hole in the side of the front end of the QHY268C camera. If there is moisture in the CMOS cavity that causes the sensor glass to fog, you can connect the silicone tube through this hole for drying.
Place an effective silica gel desiccant in the silicone rod and make sure there is cotton inside to prevent the silicone from entering the CMOS cavity.

How to prevent fogging of optical window of CMOS sealed cavity
If the ambient humidity is very high, the optical window of the CMOS sealed cavity may have condensation problems. The QHY268C has a built-in heating plate to heat it to prevent fogging. In most cases, its effect is very obvious. 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.

09 Specifications
Model QHY268C
Image Sensor SONY APS-C CMOS Sensor IMX571
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
6280*4210 (includes the optic black area and overscan area)
Full Well Capacity 
More than 75ke- on extend fullwell mode
Native 16-bit (0-65535 greyscale) AD convertor
Sensor Size
APS-C format
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
Read Noise 0.7e to 3.5e
2.7e to 5.5e in extend fullwell mode 
Dark Current 0.0005e/pixel/sec @ -20C        0.001e/pixel/sec @ -10C
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
Telescope Interface
Optic Window Type

 AR+AR High Quality Multi-Layer Anti-Reflection Coating

Back Focal Length
Reference Price
USD2399  (Professional Version)
USD2099  (Photograhic Version)


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