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INDI Library v2.0.7 is Released (01 Apr 2024)

Bi-monthly release with minor bug fixes and improvements

Optimal Sub-Exposure Calculator help

  • Posts: 17
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Hi, Joseph!

Sorry for the long scilence!
I retaken data for gain 50 of ASI294MC Pro and close around gains.

Also, I'v recieved ZWO ASI294MM Pro. I gotten and uploaded data for this camera too. I made frames with 2x2 binning as main mode of shooting. If need I'll make bin 1x1.
1 month 3 weeks ago #99178

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Thanks Vladimir, I will take look at the data when I have a chance. But I'm trying to analyze a problem in my process that can effect the results on Color cameras. I'll be making a post on this topic shortly.
1 month 3 weeks ago #99199

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Hi All,

Sorry for my slow progress and responses on the camera sensor analyzer tool. I've been trying to understand a problem in my process that impacts the results for Color sensors. (I'm fairly confident with the results on monochrome sensors).

When processing color camera data, it seems that white balance settings that are used when capturing the bias and flat images can impact the outcome of the analysis. For example, while testing my own ASI-178MC, I first used the manual white balance settings that I had established long ago, which produce mean ADU values for all color channels that are fairly even (as close as possible), WB Red 33, and WB Blue 92. The flat images appeared fairly neutral gray, (just slightly green). From this test, the resulting read-noise values from my tool were within 1% of those shown in ZWO documentation. But in a second test I set both WB Red and WB Blue to 80; the flat images appeared very red. From this test, the resulting read-noise values from my tool were generally lower (by around 3%), and the overall results over the range of gain values were less consistent (the read-noise curve had noticeable "bumps" that were not apparent in the test with white balance values that produced neutral looking flats).

My tool calculates mean values for each channel of the input data, so I should be able recognize if the input flat images are not "neutral". But I'm not certain whether I would be able to programatically compensate for this. If anyone has ideas on this, please let me know.

I had planned to develop a "front-end" process for my tool to perform the capture of the input files. In that process I might be able to control the white balance values to force the images to be neutral, but this development effort will likely take quite some time.

Thanks
1 month 3 weeks ago #99200

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Hi Vladimir,

I re-processed your ASI-294 MC data including the additional bias and flats new files you provided. I've uploaded into the ASI-294MC folder on the google share, some png files of the graphs, and also an xml file that will work for the exposure calculator. Be aware that my original code from a few weeks ago had a bug that caused some minor calculation issues, that was corrected before I re-ran this data.

But I'm seeing something in the data from your 294 MC that is interesting. If you look at the read-noise values for the "low" gains, before the camera switches modes, the values for each color channel are pretty erratic. But at gains above the point of the mode switch (around gain 120), the values of the channels is nearly identical. I'm wondering whether this is just a "normal" behavior for the read mode that is used at the lower gain settings.

I will run your 294 MM data next.
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1 month 3 weeks ago #99231
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The ASI-294MM Pro data and xml file for the exposure calculator is now on the Google share. It appears that the read-noise values I've measured with my tool are slightly lower than what ZWO graphs show for these cameras. So if you use these custom xml files in the exposure calculator the resulting exposure times will be lower than you would see using the files that we published with KStars.
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1 month 3 weeks ago #99233

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Oh! Thank You very much!
I plan to compare calculated results based on Your xml-file and xml-file that I made on data from spreadsheet presented in this message
1 month 3 weeks ago #99242

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Hi, FYI I've created a config file for the Olympus OM-D E-M5 MKII using the values from Photons to Photos , attached.

(On Mac, copy to ~/Library/Application Support/kstars/cameradata)

File Attachment:

File Name: Olympus_OM....xml.zip
File Size:1 KB
The following user(s) said Thank You: Joseph McGee
1 month 1 week ago #99564
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Hi Fred,

Sorry that I've not responded sooner regarding the camera files you provided. I learned quite a bit while processing files, and needed to add some new features to my sensor analysis tool. My tool still has some difficulty in processing color image data, (white balance settings on the camera seem to produce some aberrations in my calculations). But I've now run the data for your ASI-6200MM through a new version of my tool. A screen shot of the result is attached. (But I would not rely upon this as being an accurate result yet).

One of the new features in my tool is a process that attempts to validate input files. It will produce and display histogram data of the four input files for given gain; and it will run a few analytic tests on the data. One test is intended to detect pattern noise in the images. In a few of the flat images that you provided, my tool recognized pattern noise and generated a warning. A screen shot for that is also attached.

So I reviewed the flat files in KStars fitsviewer and see that in the flat files at gain 60, 80 and 100; the center of the images have some odd speckles. In making is assessment of a sensor, my tool only analyzes a 100 x 100 pixel region at the center of the images. So these odd speckles at the center of the images may have a significant impact in the results from my tool.
4 weeks 1 day ago #99742
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Joseph,

Thanks for the feedback. First, I'll say that the graphs are surprisingly (at least to me) close to the published specs from ZWO. Second, let me go back and see if I can get you some clean flats for those gain settings. I took a look at the frames and I can't explain why those 3 gain settings might have exhibited those artifacts. All the flat frames were taken in sequence in order of ascending gain, one pair after the other.

Hopefully get you clean frames in the next day or two.

Fred
4 weeks 1 day ago #99744

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Thanks Frederick,

I just created an ascii tab delimited data file for the current results on your ASI-6200MM. The file has values to 4 decimal places. It's in your home folder on the google share. File Name is Fred_ASI-6200MM_2024-03-14.dat

After you provide the new flat images, I'll re-run and make another file to compare, the results.
4 weeks 1 day ago #99745

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Hi Frederick,

A correction... I had made a temporary change to my code to select data from another region of the image to avoid the area where those speckles are. I forgot to undo that change when I was running tests and when I extracted the results. So I've renamed the dat file on google, and added another version. The new one is data from the center, (which is what we want to use) the other is from the corner at (1,1).

Sorry for my confusion, this project has wiped out a few of my best brain cells.
4 weeks 21 hours ago #99751

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Joseph,

I've posted revised files here: drive.google.com/file/d/14ADHoURhUkqGXb9.../view?usp=share_link. I checked the region in question in the new files and they aren't exhibiting the speckles. The cause of those is a mystery!

Thanks for all your work on this.

Fred
4 weeks 19 hours ago #99754

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