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Help needed master files  

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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 17:11  

Hi Everyone

Need some help as i can't figure out what's wrong with my master dark and master dark/flat files. I am kind of sure it not a camera issue as i have two Zwo 1600mm and both show the same issue to different levels.

I take 25 of each dark and dark/flats to make master but when i look at say the dark master in fits liberator it seem to indicate histogram levels run from about 700 all the say up to white 65533 if adjust the histogram i can see white pixels see attached tif (not as easy to see in tif) . I have only just started to use master files i used to just load the dark files and run with that. So if i look back in time back to my early work and look at the master from each project then levels are more normal 700- 7500 so i am not sure what's changed. Have i changed a setting as far as the camera but with in pixel processor not sure but i have tried two camera and both show the same issue. The single dark files look fine no issue no hot pixels just random noise levels.

Just need some help to find out what i am doing wrong here.

I can't add the fits file too big so here a reduced tif.

I have also added jpg of two screen shots of fits liberator bad is the master now and good the old master from 

good
bad

 

dark master

 Thanks in advance 

 

Mike

This topic was modified 8 months ago by Michael Purver

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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 9, 2021 17:32  

Could it be you're using a different gain now from back then maybe? Also, these are different camera's, so you can't directly compare those if the sensor is different.


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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 17:48  

Hi vincent

I am going to repeat tests but i am sure its the same gain and offset same make both 1600mm pro i am going to re-run the dark frames the old ones to make a new master if i can find them. Are those levels kind of normal then all the way up to white. I noticed this because it got some very strange final images see below its seem related to the dark and dark/flat files.

This is Lum crop using those files if you look close load of black dashes in the image please ignore levels very basic to show the problem.

andro WO Luminance crop

 

 

mike


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 9, 2021 18:52  

They shouldn't reach the entire capacity no, not by a long shot. Can you show them opened in APP so I can better judge them? Both stretched and not stretched (right hand panel, set the stretch to "no stretch"). Would be interesting to see the histogram in there as well. Might also indicate there is the tiniest bit of light leaking in or something like that. The masterdark (the last one in the first post) also shows horizontal lines which I wouldn't think are normal.


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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 19:12  

Hi vincent

Strange stretched and not stretched made no difference to the image or histogram but here is two images marked good and bad on the bad one you can see peaks on the right. Gains a little different 67 vs 100 but don't think it would have that much effect on this 

 

Mike

no stretch bad
no stretch good

 


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 9, 2021 19:46  

Selecting the "no stretch" option should change the histogram. Did you deselect it like in the screenshot here; I do think your masters look pretty normal.

Screenshot 2021 02 09 194451

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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 20:14  

Vincent

Yes that the box I unchecked it made no difference to the image or histogram i even selected the file again to make sure. So you think the small peaks on the bad i age picture to the right of the main histogram signal are normal 

 

Mike


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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 20:30  

Hi vincent

the pop up text when i hover over the button states this only effects the saved image so would it effet the live preview and histogram

Mike


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 9, 2021 20:33  

Yes, that is a UI thing we may need to improve. The top button is just to say that you want to save the stretched image or save the image, not stretched. You should select "no stretch" from the pulldown menu a bit lower, like you can see in my screenshot. 😉 But I do think it can be correct yes, just a feature of the sensor-respons. When it works fine on your data, that should also cause no issue.


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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 9, 2021 20:43  

Hi vincent

 

Ok i see that now was looking for button, Here scree

bad no stretch

n shot of the bad one the godd one just show black image and no histogram. So if these look ok why do i have all those black dashes on my final stack image attached.

 

Mike

andro WO Luminance crop

 


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 9, 2021 22:20  

I'm not really seeing black dashes, or do you mean the diagonal stripes if I zoom in? Not sure about that, but it might be a bit of walking noise perhaps...do you use dithering while shooting?


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(@moviecells)
Red Giant Customer
Joined: 1 year ago
Posts: 89
February 10, 2021 11:43  

Hi vincent

 

No dithering at the moment i am using two camera at the same time 14 inch and 80mm i use APT so it can handle dithering of multi cameras and is in fact setup but turn off in the options. Guess i am going to have to wait for clear skys to repeat some tests.

 

Thanks for the help

 

mike


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3813
February 10, 2021 12:13  

No problem, my guess is that dithering will solve this. 😉


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