Monday, October 3, 2016

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:



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. 


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, 80x5 seconds stack
M1, 200x5 seconds stack
M15, 100x5 seconds stack
M76, 100x5 seconds stack
I am pretty happy with this first results of QHY163 mono. Now time for long exposures.

Clear skies!

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