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Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Tue Sep 03, 2019 4:59 pm
by jaq1967
Hi,

I am trying, unsuccessfully, to get acceptable linear readings for this camera when running the Sensor Analysis. Firstly, it seems like it takes forever, if at all, to produce anything when running it for RAW12. 3+ hours? Is this normal? The results, when produced, give me something not very uniform.

Note: Trying to maintain a constant natural light level for this period of time is also proving difficult. I am not sure how critical this is. If natural light is a problem what alternatives do I have?

This is the best I got for RAW12 after 6 attempts:
Sensor Analysis.jpg
Sensor Analysis.jpg (302.8 KiB) Viewed 1742 times
Any ideas how I can get a better result?

Regards Jacques

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Tue Sep 03, 2019 7:30 pm
by admin
Hi,

No, it should take just a few minutes to run through. I find I get best results by adjusting the light level at the point that you are being asked to select an evenly illuminated area. I aim for an exposure of roughly 1 ms at this point and then find that the rest of the procedure runs through relatively quickly.

Cheers, Robin

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Wed Sep 04, 2019 4:18 pm
by jaq1967
admin wrote:
Tue Sep 03, 2019 7:30 pm
Hi,

No, it should take just a few minutes to run through. I find I get best results by adjusting the light level at the point that you are being asked to select an evenly illuminated area. I aim for an exposure of roughly 1 ms at this point and then find that the rest of the procedure runs through relatively quickly.

Cheers, Robin
Thanks for the reply Robin,

The Sensor Analysis for RAW12 was very slow. I am not to sure if my settings are wrong? Should I touch the USB slider??? On the other hand, scanning the RAW8 was quicker (30 mins?) and linear, as below:
Sensor Analysis RAW8.jpg
Sensor Analysis RAW8.jpg (304.78 KiB) Viewed 1717 times
I am not too sure what I am doing wrong when trying to get the RAW12 to produce something similar to the RAW8. It is very much all-over-the-place.

Any suggestions???

Regards Jacques

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Wed Sep 04, 2019 9:01 pm
by admin
Hi,

Setting the USB speed to the maximum value would likely speed up the process a bit as it increases the frame rate when you are taking short exposures. It doesn't have any significant effect once the exposure length gets above about 1/10 of a second however.

How you illuminating the sensor when you are performing the analysis? I tend to use a cheap C-thread lens with a variable aperture which allows me to focus on indoor targets and adjust the light level very easily by changing the aperture. These cost about £10 when bought from China on eBay or about twice that (typically) if bought from a local vendor for quicker delivery.

Cheers, Robin

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Wed Sep 11, 2019 3:08 am
by jaq1967
I think I finally cracked a better reading and curve for RAW12.

I purchased an illuminated tracing board on eBay. Adjustable. Not expensive. It gave a consistent light output. I don't think it gave out a pure white light looking at the histogram. Not sure if that matters? The result I got was as follow:
Sensor Analysis RAW12.jpg
Sensor Analysis RAW12.jpg (239.69 KiB) Viewed 1629 times
Only other adjustment was to kick up the USB to the first notch. If I ramped it to the second notch the system froze. It was still, nevertheless, slow in doing the reading. Perhaps the camera is a bit more involved than most out there?

Regards

Jaq

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Wed Sep 11, 2019 3:10 am
by jaq1967
Note: I thought it a bit weird how the 'Gain' curve differed when checking in RAW8 and RAW12. Is this normal?

Jaq

Re: Sensor Analysis: Altair Astro HyperCam 183C Pro: Frustration.

Posted: Wed Sep 11, 2019 5:18 pm
by admin
Hi,

The results that you have above look very reasonable to me.

If you put results for RAW 8 and RAW 12 side-by-side I would expect that the e/ADU, read noise and dynamic range figures would be different but that the full well depth and relative gain would be broadly similar between the two.

Cheers, Robin