what's wrong with this picture

[francis8]

I bought a second hand 533 MC  a couple of days ago, I was made up that the sky was clear that night so I was able to test it, wen i was imagen with nina I starting live staking with sharcap and as the images were staking i notice that the hot pixels where not aligning, and when I try to process then with siril and autostrech the image this is the result, staking them with siril didn't work, After dark subtraction, the image contains many negative pixels (99%), calibration frames are probably incorrect was the message every time i try but i tuck the calibrations frames at same temperature and gain  ,   I was using a zwo 585 before that with not problem at all, is it the camera or im i doing something wrong

[francis8]

this one was calibrated with siril without any calibrations frames, autostreched, 60 frames at 300 seconds 100 gain and l xtream filter, it was a full moon and the target realy low  so 300 seconds was a bit over kill but as i said, i was just trying the camera, giding was 0.6, 0.9, and i did manually focus

1 hour ago, francis8 said:

I bought a second hand 533 MC  a couple of days ago, I was made up that the sky was clear that night so I was able to test it, wen i was imagen with nina I starting live staking with sharcap and as the images were staking i notice that the hot pixels where not aligning, and when I try to process then with siril and autostrech the image this is the result, staking them with siril didn't work, After dark subtraction, the image contains many negative pixels (99%), calibration frames are probably incorrect was the message every time i try but i tuck the calibrations frames at same temperature and gain  ,   I was using a zwo 585 before that with not problem at all, is it the camera or im i doing something wrong

 

Edited April 9, 2023 by francis8

[rickwayne]

That last image has some hella dust-bunny signatures. How are you taking and stacking flats? Do you have a bias or dark flats?

[francis8]

2 hours ago, rickwayne said:

That last image has some hella dust-bunny signatures. How are you taking and stacking flats? Do you have a bias or dark flats?

i tuck the flats with nina, using a light panel, and stacked the lights, flats ,darks and bias with deep sky staker,  same way i always do with my other camera, apart from the camera the set up is the same

Edited April 9, 2023 by francis8

[francis8]

I don't know if this is got anything to do with it but I was searching youtube for any info and seen some one that have problems with the zwo driver on nina , so i try taking a 300 s  dark, cloudy out there  again so not chance of taking lights frames, the frame takin with the zwo driver is a bit 16 and the histogram is close to the left but with the ascom driver as you can see is bit 12 and histogram is close to the middle, withch one is correct 

[alacant]

19 hours ago, francis8 said:

the image contains many negative pixels

Hi

What offset did you use? I think 70 is the default. That should lose the negative values.

To keep it simple, take flat frames only and pre-process using a value of 70 for bias (enter =70 in  'Use bias') on the calibration tab.
Pre process then stack the flat frames with multiplicative normalisation to get a master flat.
Pre process the light frames using the same bias with the master flat
Register
Stack under additive normalisation and e.g. sigma-clip 5-2

If there's still noise (533 so I doubt it) then you can try adding dark frames.

Cheers and HTH

Edited April 10, 2023 by alacant
register

[michael8554]

Hi Francis

Your stacks have pixel trails, due to less than optimum stacking settings.

"Images must have same dimensions"

Are you trying to stack images with different bit-depths ?

Michael

[francis8]

1 hour ago, alacant said:

Hi

What offset did you use? I think 70 is the default. That should lose the negative values.

To keep it simple, take flat frames only and pre-process using a value of 70 for bias (enter =70 in  'Use bias') on the calibration tab.
Pre process then stack the flat frames with multiplicative normalisation to get a master flat.
Pre process the light frames using the same bias with the master flat
Register
Stack under additive normalisation and e.g. sigma-clip 5-2

If there's still noise (533 so I doubt it) then you can try adding dark frames.

Cheers and HTH

Hi  thanks for the reply 

offset was 50, I will give tat a go, I know you said to keep it simple, but nothing is simple when you you are a 60 year old newbie, some times a surprise my self that I learn to use all this programs haha, When you say enter =70 in use bias do you mean i don't have to take biases just enter the =70 

thanks

[francis8]

1 hour ago, michael8554 said:

Hi Francis

Your stacks have pixel trails, due to less than optimum stacking settings.

"Images must have same dimensions"

Are you trying to stack images with different bit-depths ?

Michael

Hi Michael

I'm not sure, I used the same process that I learn wile using the other camera but obviously something is not right, been trying all day to see what is wrong but with no joy

thanks for the reply 

[alacant]

22 hours ago, francis8 said:

don't have to take biases

Correct. To begin with, try without in-camera bias and without dark frames. The 533 is so clean anyway, you may find you're better without. Probably best of course, when you're familiar with the software, to try both with and without and decide for yourself.

22 hours ago, francis8 said:

offset was 50

So, enter =50 for the master bias.

Cheers 

Edited April 11, 2023 by alacant

[francis8]

On 10/04/2023 at 13:41, alacant said:

Correct. To begin with, try without in-camera bias and without dark frames. The 533 is so clean anyway, you may find you're better without. Probably best of course, when you're familiar with the software, to try both with and without and decide for yourself.

So, enter =50 for the master bias.

Cheers 

HI Alacant, your method did work, and as you said I try different ways,  darks did make everything worst, your way did the job but I tried flats and dark flats and seems to give a cleaner image, thanks for pointing me on the right direction,  for a moment I thought I bought a lemon. This one with just flats and offset values, plus have to remove the other picture it was hurting my eyes lol

 

Edited April 17, 2023 by francis8

[alacant]

23 hours ago, francis8 said:

I tried flats and dark flats

Well done, and all the more so for using experimentation to find what works for you.

Offset 50:

I'm not sure whether the 533 adjusts values between 14 bit and 16 bit. It may depend upon which software you're using.

To find out, simply take a bias frame with offset 50 using whichever capture software you use. Open in Siril and:

right clik -> statistics

Look at the median value and enter that value for the offset when processing in Siril. That should obviate the need for having to take both dark and dark-flat frames.

Cheers and HTH

Edited April 16, 2023 by alacant

[Bibabutzemann]

On 09/04/2023 at 15:15, francis8 said:

I bought a second hand 533 MC  a couple of days ago, I was made up that the sky was clear that night so I was able to test it, wen i was imagen with nina I starting live staking with sharcap and as the images were staking i notice that the hot pixels where not aligning, and when I try to process then with siril and autostrech the image this is the result, staking them with siril didn't work, After dark subtraction, the image contains many negative pixels (99%), calibration frames are probably incorrect was the message every time i try but i tuck the calibrations frames at same temperature and gain  ,   I was using a zwo 585 before that with not problem at all, is it the camera or im i doing something wrong

 

When you dither between every (few) image you would expect that the hotpixels dont allign. These artefacts should go away once you do median stacking or additive stacking with default rejection settings.

I get the same pattern like on your 2nd image when doing addtive stacking and choose "no rejection" as a rejection method.

Comparing your worklfow with this tutorial by Dominique Dhoosche may helps understanding what went wrong: https://siril.org/tutorials/tuto-manual/

Edited April 17, 2023 by Bibabutzemann

[francis8]

5 hours ago, Bibabutzemann said:

When you dither between every (few) image you would expect that the hotpixels dont allign. These artefacts should go away once you do median stacking or additive stacking with default rejection settings.

I get the same pattern like on your 2nd image when doing addtive stacking and choose "no rejection" as a rejection method.

Comparing your worklfow with this tutorial by Dominique Dhoosche may helps understanding what went wrong: https://siril.org/tutorials/tuto-manual/

thanks Patrick, I did realize  about the pixels when i actually stack them properly, and you right about the rejection method, I did that ,thanks for the link, that's what i have been doing lately, just try to find information to understand how all that part of astrophotography works,  I think I made the mistake of thinking better equipment equals great pictures without realizing the work in between  have to be as good if not better,

thanks again for the info.

Francis