QHYCCD

QHY 42 First evaluation

Re: QHY 42 First evaluation
« Reply #15 on: November 23, 2018, 10:02:03 AM »
Thank you very much for your answer and taking into account my feedback

Sincerely

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xs_man

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Re: QHY 42 First evaluation
« Reply #16 on: November 23, 2018, 04:44:00 PM »
It is not the read noise, but the thermal noise
For 2 seconds shots, it is completely neglectible

Ah yes you're right, I apologize,  I read too quickly  !

Alb?ric

Re: QHY 42 First evaluation
« Reply #17 on: December 19, 2018, 11:37:38 AM »

Enclosed is the third and last set of measures of the QHY42, devoted to exoplanet transit measurement.
In summary, the approach of taking 2500 4 seconds image (which is the limit of the full well saturation), and then to reduce to 160 mean images of 60 seconds, allow to produce high quality
results, often better than those produced by more conventional camera and "long pose" approach.
Even if this camera is not always easy to use, it is possible to take advantage of its very high QE and broad spectrum, especially in the near IR.
bonne lecture !
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QiuHY

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Re: QHY 42 First evaluation
« Reply #18 on: December 24, 2018, 09:30:47 PM »
Hello,

     Thank you very much to share the test results of the exoplanet transit measurement. That's very nice and detailed data.

     Now we are developing the QHY42PRO. To add the HDR output and the native Single Frame readout.(The QHY42 driver is taking a frame from video streaming so it is not the native single frame mode, the native single frame readout will be no the one frame delay problem and it should be easy to use in some conditions).

     When the QHY42PRO release. The QHY42 can be upgrade to QHY42PRO free.

Best regards,
Qiu Hongyun
   

   
Qiu Hongyun

Re: QHY 42 First evaluation
« Reply #19 on: December 30, 2018, 01:28:10 PM »
Hello,

Thank you Dr QIN and it is a great new, because the present single frame implementation has many severe drawbacks for DSO astronomy

Do you think it will be necessary to send the camera back to China to update it, or will it be possible to do it remotely ?

Thanks again to take my feedback into account
Bruno

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QiuHY

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Re: QHY 42 First evaluation
« Reply #20 on: January 07, 2019, 03:12:22 AM »
Hello,

        When our codes finished. I think you can send to our oversea service center to do this upgrade. Maybe faster than send back China.

Best regards,
Qiu Hongyun
Qiu Hongyun

Re: QHY 42 First evaluation
« Reply #21 on: January 13, 2019, 05:52:27 AM »
Hello Dr QIN

OK and thank you very much for your answer and the attention you pay to increase the performance of the camera, which is a bit difficult to use but incredibly fast and sensible.

I just wait your signal when the code is finished and that you telle me where I can send the camera.

Best regards

Bruno Fontaine

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QiuHY

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Re: QHY 42 First evaluation
« Reply #22 on: February 12, 2019, 04:34:13 AM »
Hello Bruno,

         I make a test image of the QHY42PRO in HDR mode. Could you please to have a check and how about the readout noise etc?  I have put the test image at http://note.youdao.com/noteshare?id=be405ee3023a82b36225e758ba7208ba  it has includes the bias, dark and flat frames. I want to do a compare with the STD mode to see if there is anything need to be fine-tune.

Best regards,
Qiu Hongyun
Qiu Hongyun

Re: QHY 42 First evaluation
« Reply #23 on: February 19, 2019, 11:53:25 AM »
Hello Dr QIN,

I just loaded the images
I have a look next days
Bruno
Officina Stellare RILA 400 F3.5 + ASA DM85 mount

Re: QHY 42 First evaluation
« Reply #24 on: February 20, 2019, 12:23:25 PM »
Hello Dr Qiu, I have measured the QHY42PRO parameters with your data enclosed  :

QHY 42PRO measurements :
Right High Gain Channel :
Gain : 0.0602 e-/ADU (16bits)   0.96 e-/ADU (12bits)  (?quivalent to G=4 setting on my own camera) Full well : 4000 e-
Read Noise : 37.7ADU = 2.3e-
Dark noise : 1.8 e-/sec (attention : 30 seconds dark frames : some pixel are saturated, not usable )

Left Low Gain Channel :
Gain : 2.02 e-ADU (16bits)  32.4 e-/ADU (12bits)
Read noise : 23.4 ADU (which is equivalent to 47 e- ! with the gain, but ADU is more significative : 23.4 compared to 37.7)
Dark noise : 3.5 e-/sec

STD mode :
Gain : 0.1 e-/ADU (16bits) 1.6 e-/ADU (which is equivalent to G=2 on my own camera - Full well : 6500 e-)
Read noise : 1.3 e-
Dark noise : 0.7 e-/sec (rather better than today )

Discussion :
With this setting, the High gain channel goes from 0 to 65000 ADU (16bits) for 0 - 4000e- and then get saturated
The low gain channel would start from  2000 ADU (4000e- ) to 65000 ADU (130000 e-, but the full well of the chip (90000e- ?) would saturated at about 45 000 ADU
May be setting the low gain channel to something like 1.4 e-/ADU (instead of 2) would give better precision with the same full well constraints ?


Hope it helps !

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Re: QHY 42 First evaluation
« Reply #25 on: March 15, 2019, 01:06:43 PM »
Hello Dr Qiu

It seems that the new version QHY42PRO is not available (documentation on the web site)
If it is, would it be possible to upgrade my QHY42 to the PRO Version ??
Officina Stellare RILA 400 F3.5 + ASA DM85 mount

Re: QHY 42 First evaluation
« Reply #26 on: March 16, 2019, 11:38:21 AM »
Dears,

I just measured data in STD mode using Basic CCD Parameters script in Pixinsignt:



My question is, taking into account that gain is set to a very low value, why Full-well capacity is so limited? 

Regards.

Re: QHY 42 First evaluation
« Reply #27 on: March 21, 2019, 12:50:32 PM »
The gain of 0.097 e-/ADU is the gain in a 16 bit range (0-65535); the ADC (analog to digital converter) inside the camera is 12 bits long only (due to fast acquisition in video mode) and the value captured by the camera is 4 bits left shifted (multiplied by 16)  before being transmitted to the interface. The "real" 12 bits gain is then 0.097 * 16 = 1.552 e-/ADU 12bits. As there is only 2**12 (4096) ADU in a 12 bits register, the saturation (of the ADC not of the pixel in the camera) is reached as soon as 4096 * 1.552 = 6356 ADU (CQFD!) Of course, it is the same if you multiply the 16 bits gain by 65635 : 0.097 * 65535 = 6356 but it is less clear for the physical interpretation.

Comments : those new BSI camera are very sensitive in a broad spectrum but the saturation arrived very rapidly. It is perfect to detect and to measure very low signals (star photometry) but inadequate for contrasted images like a wide angle DSO image.
That is why FLI and now QHYCCD with the PRO version of the QHY42, have implemented the possibility to have a dual channel mode : in STD mode, it is like now with a high gain adjustable image, but in HDR mode, you get simultaneously two images : one high gain on the right and one low gain on the left in the example below. In that mode, two gains are fixed (see discussion above).
The first example below shows a low illumination level (where right image is interesting) and the second example shows a more illuminated image where the right image is saturated and the left image is interesting. It is  possible then to produce a composite image by a formula like lowgain (12bits) * k + highgain (12bits) on a higher (16 or more bits wide)
Hope it is clear (it took me some time to understand!)
Officina Stellare RILA 400 F3.5 + ASA DM85 mount

Re: QHY 42 First evaluation
« Reply #28 on: March 21, 2019, 12:53:12 PM »
Sorry for the mistake for my post of te availability of the PRO version of the QHY42
As it seems NOW available, can I have mine updated to the PRO version in your european facility ??
Officina Stellare RILA 400 F3.5 + ASA DM85 mount

Re: QHY 42 First evaluation
« Reply #29 on: March 22, 2019, 05:28:41 PM »
Hi Bruno, thanks a lot for your explanations,

coming from years and years using 16 bits CCD... this is a quite new for me :)

It is clear that these cameras are not good for classic DSO imaging, but great to detect  and measure faint objects.

Kind regards!