Sensor analysis

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stephen2615
Posts: 21
Joined: Sat Mar 09, 2019 11:10 pm

Sensor analysis

#1

Post by stephen2615 »

Greetings,

I have searched on this but nothing meaningful is returned. I am trying to do Sensor Analysis on my QHY 163C and when I started the process, I moved the two little red arrows (that form some area) to another area and then started the Sensor Analysis again but it complains about "Selected area too small. Please select a larger area". My problem is that I can't seem to move the arrows to adjust the size. Other answers about Sensor Analysis say to adjust the arrows but they are not going anywhere.

Any ideas?

Regards

Stephen
Last edited by stephen2615 on Sat May 16, 2020 1:51 am, edited 1 time in total.
stephen2615
Posts: 21
Joined: Sat Mar 09, 2019 11:10 pm

Re: Sensor analysis

#2

Post by stephen2615 »

I discovered the problem. The (invisible to the naked eye when not zoomed in) rectangle inside the two arrows was high but had no width. After zooming in, I could see it needed to be adjusted width wise.
stephen2615
Posts: 21
Joined: Sat Mar 09, 2019 11:10 pm

Re: Sensor analysis

#3

Post by stephen2615 »

I was able to start it and it was going nicely for the first part. Then when doing the second part, it complained that the needed exposure was shorter than the min exposure of the camera (QYH 163C). This took a LOT of lighting adjustment settings. I finally was able to use my LED head lamp for a lighting solution on a wall which has two different brightness settings. If when doing the first part and I was able to use anything above 1 sec exposure, it probably would not have been too much of a hassle for the second part. I dread trying to use this on my QHY 16200A which is ultrasensitive.
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Re: Sensor analysis

#4

Post by admin »

Hi,

what version of SharpCap are you using? In recent versions I have changed the way that the initial illumination level is set up to try to make it less likely that you will run into this sort of problem.

The way to tell the difference is :

* Old way - initial exposure setup is done at high gain, target is an exposure of a few ms.
* New way - initial setup done at minimum gain, target is an exposure of ~0.5 to 1s

If you are trying to do this with a version of SharpCap that uses the old way then do try updating.

thanks, Robin
stephen2615
Posts: 21
Joined: Sat Mar 09, 2019 11:10 pm

Re: Sensor analysis

#5

Post by stephen2615 »

Hi Robin,

Thanks for the response. I am using the latest downloaded version of SharpCap.

The problem is when I do the second part of the sensor analysis where SharpCap drops the exposure time down below the 6 microseconds the camara has as a min exposure.

I don't know if what I do to adjust the illumination when SharpCap complains about the various levels of brightness does anything to the measurement. I have a led headlamp illuminating the area the sensor is using. Depending on the amount of light needed, I either have one set or two sets of leds operating. It seemed to work ok in the end. I have a QHY 163C and I had all sorts of issues with it. I had to remove the QHY SDK and then SharpCap and then install SharpCap again to let it use your QHY drivers. if I have the SDK installed, nothing seems to work.

BTW, what does Signal (% of max) mean in the final result? Eg,

Exposure (ms) Signal (% of max)
15.25509844 2.219807419
30.51019687 3.18889084
76.27549218 6.140990555

I have looked at your work about exposure and figured out my camera works best at about 70 seconds. It so far has produced excellent results.

Regards

Stephen
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Re: Sensor analysis

#6

Post by admin »

Hi,

The information regarding % of max relates to SharpCap attempting to measure the sensor's linearity of response to increasing illumination (SharpCap gradually runs longer and longer exposures and has to assume that the light level on the sensor remains constant).

If you could run the sensor analysis and then go to the SharpCap logging capture all the text and share it here (or in a private message to me) I could have a deeper look at why you are running into problems.


Cheers, Robin
jdaliix
Posts: 17
Joined: Mon Jun 11, 2018 2:01 am

Re: Sensor analysis

#7

Post by jdaliix »

This looked like as good a place to post this as any. I sat down and did sensor analyses for all five of my color cameras. The ones that worked normally are the ASI2400, ASI533 and ASI385.

The ASI294 went through all the processes normally, but the finishing report showed 0 values in all columns. I did the analysis three times. Any ideas? Or could someone tell me what their analysis produced for close to unity gain on a color ASI294? I'm assuming I can't use the smart histogram with this camera without a legitimate report?
Image
http://spacestreams.com/images/asi-294- ... alysis.jpg

The ASI2600 also went through all the processes normally, but the finishing report showed no value close to 1:1 e/ADU. I did the analysis twice. The closest it got was .72 at 0 gain. Is this normal for this sensor? Has anyone seen a different analysis than this? Or come up with a close-to unity gain that would be useful?
Image
http://spacestreams.com/images/asi-2600 ... alysis.jpg

Edit: the image URL tag didn't work, so I added direct links. If I need to email the screenshots or anything else, let me know.

Thanks very much,

-- Jason
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Re: Sensor analysis

#8

Post by admin »

Hi Jason,

the 2600C result is pretty much what you would expect – this camera has a 16 bit ADC and a full well depth of about 50,000 electrons. That means there isn't a way for this camera to get unity gain. If you have a look at the ZWO site you can see that their specs for the camera reflect this too : https://astronomy-imaging-camera.com/pr ... -pro-color

I'm intrigued by the 294C report. I haven't seen anything like that before. I can see from the screenshot that you were running the report in 8 bit mode – does it make any difference if you run it in the 16 bit mode of the camera? I'd also suggest making sure you're on the latest SharpCap to take advantage of any fixes that have gone in recently (you might even want to try the SharpCap 4.0 beta). If none of this makes any difference then please could you capture the full contents of the SharpCap blog after the sensor analysis run and send it to me – hopefully that will allow me to spot where the calculations have gone astray.

Cheers, Robin
jdaliix
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Re: Sensor analysis

#9

Post by jdaliix »

Hi, Robin.

I'll be danged. I thought I was vigilant on setting 16 bit for all of them. I think I know what happened, though. I bumped the USB and it dropped the camera connection in the middle of the dark phase. I think I reconnected and just plain forgot to set 16 bit.

I'll try that.

If it comes down to me needing to get the log, where is it? It isn't just the simple Copy to Clipboard, right?

Thanks,

-- Jason
jdaliix
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Joined: Mon Jun 11, 2018 2:01 am

Re: Sensor analysis

#10

Post by jdaliix »

Robin, I don't know if switching to 16 bit was what did it, but it worked.

Thanks for your help.

-- Jason
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