Camera Analysis on a ZWO ASI294

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RudyOtten
Posts: 1
Joined: Fri Feb 08, 2019 6:50 pm

Camera Analysis on a ZWO ASI294

Post by RudyOtten » Fri Feb 08, 2019 7:06 pm

Good day Gents,

I use SharpCap now for more than a year and I got the license for life-time (Hope to become 114 :D )
Today I tried to use the feature to measure the performance of the camera so it can be used by the smart Histogram.
I'm a bit puzzled with the outcome as I had to redo it 3 times.
The first time it indicated that the brightness level was too much, so I decreased it. (I'm using my light box with dimmer for that).
Then it complained about that it was to dim and that the time to capture all the data was to long.
I found a setting and it did the first part, I got the graph with the straight line.
I then got the question for covering the scope to measure the dark current noise.
And after that it continued but gave at the end an error aying:
Minimum exposure reached. Reduce the light level and try again?

Interesting is to mention that when I now press the brain button it does show a graph
and it does give me an optimum exposure time. But I have no idea if they are now valid or not.

I attached the screenshot at the moment of the failure message.

Any input is welcome.

Regards,

Rudy
Failed.png
Failed.png (614.84 KiB) Viewed 483 times

lanmat
Posts: 5
Joined: Mon May 27, 2019 2:29 pm

Re: Camera Analysis on a ZWO ASI294

Post by lanmat » Mon May 27, 2019 2:37 pm

I'm getting the same thing w/ the sensor analysis tool. I have a QHY183M and I get through the e/ADU & dark noise measurements, but it always hangs on the next step (dynamic range?) complaining about minimum exposure reached. Problem is, after the dark noise step, it won't let you proceed unless the image is saturated, so I can't turn the light down too much or I can't start the next test. The only option is to press "Cancel", try and lower the light level, stop down my lens, or dim my light box further, and start all the testing over again, with the first test taking SUPER long b/c of the low light level.

It'd be nice to break each test up & save the results so we can start again from a specific step if we run into problems. And it might be nice for a little more direction on brightness of the source. For instance, if it's trying to get a specific histogram peak ADU at each gain step, then do a first run @ highest gain & lowest gain to see if the lighting is right, and notify the user to dim/brighten the light.

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admin
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Re: Camera Analysis on a ZWO ASI294

Post by admin » Mon May 27, 2019 9:05 pm

Hi,

Sometimes certain models of camera have a very wide gain range which makes it very hard to find a brightness level that will let the relative gain measurements be run without either bumping into the minimum exposure of the camera at high gains or ending up with exposures of many seconds or even tens of seconds at very low gains. Since the exceptionally high gain values are usually more of a gimmick than actually useful for imaging, SharpCap limits the maximum gain it will try to measure if it thinks such circumstances going to occur.

This works nicely for most qhy cameras where the numerical gain value is the magnitude of the gain either in dB or 0.1 dB. However I've had some reports recently of some models where the gain numerical value seems to work in a different way so that it is not directly connected to the gain of camera in dB. In these cases SharpCap doesn't know in advance that it needs to take steps to limit the range of gains being measured.

It would be very helpful if you could report a couple of measurements for me.

* The minimum and maximum numerical values of the gain slider for your camera.
* The exposure times required to give a 50% histogram peak at minimum and maximum gain values under constant illumination.

That will give me a better understanding of how the gain control works on your camera and might let me work out an approach that would make this work more robustly. Another useful piece of information would be the full SharpCap log file from an attempted calibration run, as lots of diagnostic information about the measurements being made ends up in the log file.

Cheers, Robin

lanmat
Posts: 5
Joined: Mon May 27, 2019 2:29 pm

Re: Camera Analysis on a ZWO ASI294

Post by lanmat » Fri May 31, 2019 5:55 pm

I finally got it to run, but on the 2nd attempt it failed. I tweaked the light panel a bit and it succeeded on the next run. Here's the log in case it's useful. My first guess is that my histograms were pretty wide @ the high gains (spanning from 20-80%). Also, on the results the read noise seemed to have a bit of a hiccup around the 10-20 gain step. Is this normal?
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SharpCapLogs.zip
(276.89 KiB) Downloaded 6 times

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Re: Camera Analysis on a ZWO ASI294

Post by admin » Fri May 31, 2019 9:03 pm

Hi,

Do you have a screenshot showing the final graphs and table of values? Much easier for me to start off by looking at that then digging through the logs!

Cheers, Robin

bazza104
Posts: 6
Joined: Mon Jun 04, 2018 12:13 am

Re: Camera Analysis on a ZWO ASI294

Post by bazza104 » Wed Jun 05, 2019 11:12 am

No expert but I have a ZWO ASI294MC Pro and was getting the same problem.
I noticed your Capture area was the same I had with the same errors.
I clicked up to the next biggest area and my troubles went away and I had a pretty good nights astrophotography using the the settings made after sensor analysiswas completed.

Regards

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