Thanks for the revised data Frederick,

I re-ran the analysis with the revised flat files, it definitely changed the results for gains 60, 80, and 100. Onto the google share folder I've uploaded a new data output file, Fred_ASI-6200MM_Center-Revised-2024-03-16.dat which can be compared with Fred_ASI-6200MM_Center-2024-03-15.dat if you care to see what changed in the results.. A screen shot of the graphs from new analysis is attached here (and a copy is also on the google share).

The only substantial difference between the ZWO data and results from this tool have to do with identifying exactly where the mode switching occurs in this camera (that abrupt drop in read noise). Per ZWO the mode switching occurs at gain 100. From the data we used in my tool I can only say that happens between 80 and 100. If you are curious to know exactly where that switch occurs, we would need to include bias and flats that are slightly below 100.

But, I think my next effort on this project is going to be developing a process that will drive the acquisition of the bias and flats images. In that process I hope to be able to automatically identify where cameras are doing mode switching. I also need to develop some processes to resolve issues with white balance settings on color sensors. So if you have no urgent interest in knowing where that mode switch is occurring, that's fine; hopefully the data acquisition function will be able to find it for you when I get this tool to the point where it can be deployed.

Joseph,

Thanks for the work you are doing on this. I usually shoot at gain = 0 so I haven't spent much time sorting out exactly where the mode switching occurs. If it is of use to you, I'd be happy to do some more work with the camera and test intermediate gain levels - just let me know. Heading into a week or more of cloudy weather here.

If you are interested in the data, advice on how to approach the project would be great. For example, would it make sense to start at gain = 100 and just back down by 1 unit for each set of frames? I'm not sure I know how to recognize when I hit the mode switching point so would I just continue to shoot in 1 step increments all the way down to gain = 80?

Best,
Fred

Thanks Fred,
At the moment I've been focused on developing the camera client process that will allow my tool to capture the Bias and Flat images needed for the analysis process.

Fortunately, I own a camera that has a mode switch, (it's my guide camera is an ASI-290MM Mini). So I have what I need for testing a process to detect at which gain a mode switch occurs. But feel free to put more Bias and Flat images onto the google share. I can certainly include them and run them through my process to give provide you with a more precise graph and data for your camera.

In case you are interested, here is what I found while working on the capture process:

The point at which a mode switch occurs, can actually be seen in changes of statistics in bias images. My ASI-290MM has a switch that occurs at around gain 60. In the initial tests with my tool I only took images at intervals of 20 units of gain. So my 1st graph jumped from 40 to 60, and did not show precisely where the switch occurred. So I ran some tests manually using KStars Indi control panel, using increments of just 2 units of gain, starting well below where the mode switch occurs. I simply noted values for the statistics to see trends. In the attached "ModeSwitching.png" you can see that the values for Mean and Standard Deviation were generally climbing from gain 52 through 60. But at gain 62 there is sudden drop, then the values resume climbing. So I captured another image at 61, and determined that mode switch does, in fact occur between the 60 to 61 gain settings.

So I should be code a detection process that isolate these mode switches.