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Old 21-12-2024, 05:33 PM
TrevorW
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Noise

Is there anyway you can test a cmos camera to see if the sensor excessively noisy - I know a lot of factors contribute to noise - but outside the normal issues it seems to me that the data I have been capturing using the ZWo1600GT Mono with LRGBHa filters is not as smooth as the data I usually capture with the QHY268c especially with longer exposures
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Old 21-12-2024, 10:45 PM
gb44 (Glenn)
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?

The data file that comes with each QHY exposure has a noise measurement doesnt it?
Do you get the same with a ZWO exposure?
You could compare it to other users cameras / a new equivalent sensor maybe?
You could compare the measurements from differing sensors...

GlennB
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Old 22-12-2024, 01:43 PM
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rmuhlack (Richard)
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PixInsight has the "Statistics" process that displays image info such as minimum/mean/median/maximum/average deviation etc. Siril may have something similar, which you could use to compare dark frames between your two cameras.

The gain and temp settings that you've chosen will also play a factor (because as you say, there are many aspects to noise: dark noise, read noise, shot noise etc)
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Old 22-12-2024, 07:16 PM
Startrek (Martin)
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Trev,

I’m no technical geek but the specs don’t lie ….. ,

Can’t really compare the individual performance of these cameras as it’s chalk and cheese

The QHY268C camera has the latest generation Sony IMX571 back illuminated sensor ( same as my ZWO2600MC and ZWO2600MM ) with a 16bit ADC and a Quantum Efficiency ( QE ) of over 80% and 90% respectively.

The ZWO1600MM camera has the older technology Panasonic MN34230 sensor with a 12bit ADC and QE of around 60%.

Read noise for the QHY268C is significantly lower due to the High Conversion Gain HCG technology at Gain 100.

Dark current for the 1600MM at -5C is 0.01600
Dark current for the QHY268C at -5C is 0.00010 which is a huge difference !!

Without factoring in imaging conditions ( Skyglow , Moon glare , seeing conditions etc… ) or imaging parameters ( Gain , offset , cooling temperature, exposure length etc… ) between OSC and Mono , the QHY268C has the wood over the 1600MM in regard to camera performance , efficiency and inherent noise from the operation of the camera itself.
Thats not to say that the QHY268C is a better camera than the 1600MM , they both are excellent cameras within their own right.

Provided your 1600MM is functioning correctly including cooling , your taking advantage of Calibration ( Darks to calibrate your Lights , Flat darks / Bias to calibrate your Flats ) and your dithering your frames, I personally think and suggest your 1600MM needs some decent integration time to optimise it’s performance in regards to SNR. Most of your images posted lately have been only around a couple of hours or so , quite short. I’d like to see what 8 to 12 hours of data or longer can do. I’m confident you will be pleasantly surprised.
Since using my Mono for the past 18 months , I initially thought that I could get away with shortish integration times compared to my OSC. I found it’s actually the opposite, the more data I gather the better the Mono ( 2600MM ) shines with reduced noise and image fidelity.
For me under my B8 skies , Broadband is 12 hours minimum and Narrowband is 6hrs minimum integration to produce a half decent low noise image. From memory your imaging under B6 skies in suburban Perth which is not exactly darkish skies , so integration time together with calibration and cooling is a big factor in improving SNR ( obviously a higher QE camera will yield better results too )

Cheers
Martin

Last edited by Startrek; 23-12-2024 at 09:18 AM.
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Old 25-12-2024, 10:16 AM
TrevorW
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My recent image of NGC1761 is 9 hrs data although very low in the sky and captured under a full moon so probably not a good target to measure the performance of my mono camera. The image of NGC3199 was not affected by moon glow as much being higher in the sky. As you rightly pointed out the QHY has a lower read noise so I am probably expecting to much from the ZWO camera. The filters I am using are Optolong which may be causing some flaring. I purchased the camera to try my hand at Mono, although I would have preferred the QHY268M, my budget would not stretch to that (yet). Merry Xmas
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Old 26-12-2024, 11:56 AM
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ChrisV (Chris)
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Sharpcap has a sensor analysis routine. Among other things, gives noise at a range of camera gain settings.
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Old 01-02-2025, 09:55 PM
astroimagery (Karl)
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Also Siril has a nice noise readout for your images.
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