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Orion's Belt

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#26 andysea

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Posted 25 November 2022 - 01:31 PM

Love it!

FWIW the artifacts on the bright stars don't bother me. I have had those on many images too.



#27 wb6pco

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Posted 25 November 2022 - 02:27 PM

Yes.

 

In Photoshop:

 

1) Select a square centered around the star you want to work on.

2) Copy, new document and paste. Flatten layers of this small image.

3) Apply Russ Croman's Star XTerminator using his process to separate star and nebula layers.

4) Turn off stars and select nebula layer.

5) Use the oval selection tool to draw a circle centered on the star. Set feathering for the circle to an appropriate amount for the size of the star. I used 50 for a large star.

6) Use Filter: Blur: Radial Blur set to 100 (max setting).

7) Might be necessary to apply a 2nd radial blur.

8) Turn on stars layer and flatten image.

9) Select all, copy and paste into original image. It should go right into the correct location if the original selection square is still there.

10) Flatten layers.


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#28 Daveone

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Posted 26 November 2022 - 01:42 AM

Hello, someone said here , that the problem may be caused by some lens cell holder on the edge of optics. If so, you can easily go up little bit with f so you do not use f,2,8 but let’s say f4 (do not know the stops you can make with this objective) and get rid of it. Sure you will do so only for some short imaging time , rest you do with f2,8 as ussually . Then you fast process the picture with used f4 and you use(clonestamp for example ) only those bright stars without artifact for your main image. Sure that only for the next time .. not sure if you can go and shoot another short set of raws for same object with diffrent f any more . It is little bit ,,painting,, but worth to try for otherwise perfect optics and so beautifull pictures you are making wink.gif 
Of course this will work only if really you will ever get bright stars without artifact with higher aperture (f)setting . I know some of the TAKs APO refractors do have similar so called ,,butterfly,, artifact around bright stars .

David


Edited by Daveone, 26 November 2022 - 01:48 AM.


#29 wb6pco

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Posted 26 November 2022 - 05:02 PM

Dave,

 

Thanks for the suggestions. The aperture on the lens cannot be controlled without a camera body. An aperture stop on front of the lens might work.

 

I can see where it might be difficult to get a different series of images to blend in correctly if they were not processed exactly the same. 

 

Star XTerminator is not handling the "butterfly" stars consistently which is causing another problem. Russ says the next version should do a better job.

 

Chuck



#30 Zambiadarkskies

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Posted 27 November 2022 - 10:48 AM

Dave,

 

Thanks for the suggestions. The aperture on the lens cannot be controlled without a camera body. An aperture stop on front of the lens might work.

 

I can see where it might be difficult to get a different series of images to blend in correctly if they were not processed exactly the same. 

 

Star XTerminator is not handling the "butterfly" stars consistently which is causing another problem. Russ says the next version should do a better job.

 

Chuck

You could set a desired f-stop, with a Canon body, press the DoF preview button and then remove the lens while it is powered on.  This should then allow the lens to be used at narrower apertures.  Like you and others, these aperture aberrations don't bother me too much.  My Nikkor 180mm has them too on brighter stars.  


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