QHY163M first light, first impressions

A few days ago I have received one of the first QHY163M cameras. This is the one http://www.qhyccd.com/QHY163.html . That is a direct competitor to ASI1600 camera. Differences are as follows: QHY163 has two stage cooling that allows to reach temperature drop 40*C below ambient (I have checked and it is true). It also has built in 128MB memory buffer and heated chamber front window. 
Camera has come in the plastic case:

Camera in pelicase and color wheel
Pelicase content – camera, cables, dessicant, 2″ adapter

After installing drivers from QHY webpage all has been detected without any problem (Lenovo T420s laptop with Windows 10). Camera is working well controller with EZCAP and MaxIm DL 6.13. When cooling is switched on the sensor reaches temperature drop about 30*C within a minute, and within another minute it reaches maximum drop of 40*C. Cooling fan works pretty quiet (it makes less noise than for example the one in Atik383 camera), and the camera case becomes little warm after some time due to the heat collected from the sensor and from the front window. 

Camera front – 2″ dovetail has T2 thread inside. Dovetail can be unscrewed and custom adapter can be attached using four M3 screws
Camera back. Four pin socket is for connecting filter wheel, so we don’t need to have separate USB and power for the wheel. Cool!

Here are the two frames at -10*C sensor temperature: 60s dark and bias. PixInsight autostretch:
I have measured camera linearity and it looks very good (gain=0, offset=40):
Basically up to 60000 ADU plot is perfectly linear:
Then using method described for example here http://www.phy.cuhk.edu.hk/djwang/teachlab/projects/CCD/CCD%20Camera%20Gain%20Measurement.pdf I have measured real camera gain and the value is g=0.26e/ADU.
Having this it was pretty straightforward to calculate full well depth that is 17100 electrons assuming the response is linear till the max ADU. But the plot drops at the end, so for further calculations I assumed the pixel depth is 18000 electrons, and it gave following calculated results:
First column is gain set in the camera driver settings. Second column is measured signal for 1s exposure. Then third columns is real gain in dB, and in the next column real gain in electrons / ADU. Then we have camera read noise, saturation and dynamic range both in EV and dB. Last row is Atik383 values for comparison.
Read noise is pretty impressive in my opinion. 

First lights have been made during star party in Zatom, Poland. I used SCT8″ with Alan Gee Mark II telecompressor and CG5GT mount without guiding. I have shot 5 seconds exposures, and camera settings were: gain=20, offset=100, sensor temperature -25*C.
NGC891, 80×5 seconds stack
M1, 200×5 seconds stack
M15, 100×5 seconds stack
M76, 100×5 seconds stack

I am pretty happy with this first results of QHY163 mono. Now time for long exposures.

Clear skies!

6 thoughts on “QHY163M first light, first impressions

  1. Very interesting, thank you very much. I have a question about the reported table. It tells the gain value, but not the offset. Since the offset adjust is important to increase the bias level to the correct value I wonder if you raised it when raising the gain.

    Thank you in advance and best regards


    1. Hello Mauro,
      Yes, you are totally right. I needed to adjust offset setting for every gain to have bias frame histogram separated from the left side. But for day to day picturing I use only two gain settings – for long exposure I have GAIN=0 OFFSET=40, and for shorter I use unity gain setting GAIN=12 OFFSET=64. These settings works well.
      From testing I only remember that for GAIN=40 and more I needed to set OFFSET to maximum value 255, but so high gains are reserved for planetary imaging I think.

  2. Dear Lucas,

    another question: in the second column you state that there is the measured ADU level for 1 second of exposure. Is it the mean ADU level reached and measured onto a dark frame or a master dark frame? How is it possible that you have a value over 65536 for gain=50? I can justify this only if you have a multiple stack of dark frame.

    Can you explain this, please?

    Thanks and best regards


    1. Hi Mauro,

      This 1s exposure is a flat frame – I exposed white illuminated wall, then made a small crop of the frame center and measured average signal in ADU (these flat frames were calibrated each time with master dark and master bias). Actually I made a few flat frames for each settings and then averaged result.
      And you are right for gain=50 result – I made here shorthand and have not explained it. For this specific setting I made 0.1s exposures, averaged them, and then multiplied result by 10, so it is extrapolated to 1s exposure time. 1s exposure was oversaturated for this setting.


  3. Hi,
    Very interesting review. I’m considering getting one of these cameras over the asi1600mm.
    Is it possible to thread a filter directly to the camera? (like a 1.25 Halpha filter) and use it like that for mono only.
    I know the Asi version allows that from the box.
    Thank you,

    1. Hello Tudor,

      In QHY163M there is no direct way to attach 1.25 filter to the camera 🙁 I agree it would be pretty convenient. What you need is a low profile adapter with T2 male thread outside and 1.25 filter thread inside. It can be screwed into the camera 2″ dovetail nosepiece (there is T2 thread inside) and you can place a filter inside. Something like this http://www.teleskop-express.de/shop/product_info.php/info/p7514_Baader-continuous-male-T2-thread-with-1-25–Filterthread.html . But this is not available out of the box.

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