PixInsight Forum (historical)

PixInsight => Tutorials and Processing Examples => Topic started by: rtemen on 2016 June 17 10:49:15

Title: Gain in electrons/ADU for T3i
Post by: rtemen on 2016 June 17 10:49:15

I am using PI to process my pics. I am following the instructions suggested to me over at Light Vortex.
I am at a place where it is asking me to enter the gain of my camera chip in e/ADU.
I have not been able to find this information for several hours now.
Does someone have a chart of gain values for different cameras?
I have a Rebel T3i (600D).
Also, it was suggested that I could use the script Basic CCD Parameters, but it crashes when I try to use it.

Thanks,
Rich

Title: Re: Gain in electrons/ADU for T3i
Post by: Jim Selph on 2016 June 18 07:27:26

You have to have three sets of two each images open to use the function or it will give an error. Open two Bias frames, two Flat frames and two darks, one dark at 600 seconds and one dark at 60 seconds. I had it do the same thing till I opened those images.

Title: Re: Gain in electrons/ADU for T3i
Post by: rtemen on 2016 June 19 06:55:43

Thanks, that worked.
Rich

Title: Re: Gain in electrons/ADU for T3i
Post by: starwind on 2019 September 16 17:59:01

Can you share what values you got? I'd like to use for my T3i. Thanks.

Title: Re: Gain in electrons/ADU for T3i
Post by: copello on 2019 September 17 00:35:54

Hi there,

I did the experiment for the Rebel (T5i, 700D). Here are the results as table screenshot (see attachment).

Cheers
 Thomas

Title: Re: Gain in electrons/ADU for T3i
Post by: starwind on 2019 September 19 17:09:15

Rich, I shared my values for the T3i here:
https://pixinsight.com/forum/index.php?topic=13966.0 (https://pixinsight.com/forum/index.php?topic=13966.0)

Thomas, for the T5i I suspect the full well depth at ISO 100 is lower. Might want to verify what max DN you get at ISO 100. IN my case it was lower than that at higher ISOs indicating that full well depth was only 24828 electrons.

Also for DR, not sure the PI script considers the significant bias at all ISOs. In the case of my T3i it is ~2048. And max ADU was only 15831. This means there are only 13783 DN avail above ISO 100.

Title: Re: Gain in electrons/ADU for T3i
Post by: copello on 2019 September 20 01:26:24

I did also a linearity test, and indeed for ISO 100 the saturation occurs around 13800 ADU (see screenshot).

Title: Re: Gain in electrons/ADU for T3i
Post by: llpastro on 2019 September 20 07:10:52

Would someone please point me to where on the Light Vortex website the procedure for calculating camera gain is located?  Thanks.

Larry

Title: Re: Gain in electrons/ADU for T3i
Post by: starwind on 2019 September 20 16:40:46

Are you looking for this?: https://www.lightvortexastronomy.com/measuring-your-camera-sensor-parameters-automatically-with-pixinsight.html (https://www.lightvortexastronomy.com/measuring-your-camera-sensor-parameters-automatically-with-pixinsight.html)

Title: Re: Gain in electrons/ADU for T3i
Post by: starwind on 2019 September 20 16:43:04

Quote from: copello on 2019 September 20 01:26:24

I did also a linearity test, and indeed for ISO 100 the saturation occurs around 13800 ADU (see screenshot).

If you use this new max value and subtract the roughly constant bias, i'm assuming you will get a smaller full well capacity at ISO 100 vs. what you stated before.

Title: Re: Gain in electrons/ADU for T3i
Post by: llpastro on 2019 September 21 07:37:44

Starwind, thanks.  That is what I was looking for.

Larry