Problem With NEF Files

[terry59]

When I take subs using my Nikon D50 and a Hutech IDAS LPS filter the batch pre-processing script works fine. When I use a Baader Ha filter I have issues. I found that converting  the NEF files to DNG, along with some other caveats, is sufficient to get pre-processing to complete.  I am attempting to attach a shot showing a STF applied to a NEF. Any assistance is appreciated.

Terry

[Juan Conejero]

Hi Terry,

What kind of issues are you having? I don't see any stars on the screenshot you've posted, so I wonder if the problem is with image registration.

Could you upload one of these NEF files, so I can take a look at it?

[terry59]

Hi Juan,

  I'm basically unable to use the NEF files at all when the subs are from shooting through a Ha filter. I discovered that if I convert them to DNG, I can use them. I have had problems with other NEF subs and will try converting those as well. If you can tell me why the NEF files aren't working and can confirm that the corresponding DNG files are good that would be great. I tried uploading a NEF file but it is 5.5 mb and the file size limit appears to be 512 kb.

Thanks very much for your help!

Terry

[Juan Conejero]

Terry,

I have just created an account for you on our Endor file server. You should have received an email with your account's user name and password.

You can upload your file(s) to Endor and share them with me (jconejero). Or you can upload them to the 'Forum Shared Files' repository so all of us will be allowed to see them.

[terry59]

Juan,

  I've uploaded a NEF file and it's corresponding DNG file from two imaging sessions where I used the Baader Ha filter. One of them is IC 1805 and the other is NGC 7035. As reference, I uploaded a NEF file from a third session, NGC 1027, where all of the imaging equipment ws identical except I used a Hutech IDAS LPS filter. The NGC 1027  NEF file looks different than the others using the STF and batch processed as well.

  I am very curious to see what you find. Thanks again!

Terry

[Juan Conejero]

Hi Terry,

Thank you for uploading the images. The images are very weak, and StarAlignment with default parameters is detecting many noise structures as false stars.

In the attached screenshots, I have used SA in "detected stars" mode on a preview of your (deBayered) NEF image. With default parameters, SA detects thousands of false stars. Increasing the sensitivity star detection parameter to zero (the default value is -1), the problem gets fixed.

I see three workarounds to this problem:

- Increase the exposure times to gather more signal. These raw images are too weak in my opinion.

- Register your images manually, after calibration with the BatchPreprocessing script (disable the registration option in the script). In this way you can set the sensitivity parameter to zero.

- If you feel hacking-inclined, you can modify the BatchPreprocessing script's source code. See the next post (the forum administrator doesn't allow me to post more than 512 KB, hmm...)

Hope this helps.

[Juan Conejero]

If you want to use a custom version of the BatchPreprocessing script (brave!), here's how you can do it. I post this information here also to encourage other users to customize scripts. It is much easier than what may seem at first sight.

1. First make a working duplicate of the script. If you are using Windows, you'll find it on this folder:

C:\Program Files\PixInsight\src\scripts\BatchPreprocessing

This is a protected folder, so you should copy it to another location where you have write permission. For example, to your "My Documents" folder.

2. Open the "BatchPreprocessing-engine.js" file with a good code editor. For example, use PixInsight's Script Editor.

3. See the attached screenshot. Around line 980 you have to add a new line with the following text:

SA.sensitivity = 1.000;

4. Save the file by pressing Ctrl+S (with the Script Editor window active).

Now you can run the modified script. From the main menu, select "Script > Execute Script File" and select the "BatchPreprocessing.js" file on your working duplicate folder. Good luck!

[terry59]

Thanks for looking into this Juan. Longer Ha subs have the same issue. It must be the camera/NEF files but it sure is frustrating