ASI294MC What am I doing wrong !

[daveangie0110]

Hi all

Can anyone help.

I just purchased a ASI294MC Pro camera,  I tried it out for the first time on my Redcat and a UV/IR filter, from my very light polluted garden (Bortle 8-9) I shot 25 x 180 second exposures at 120 gain and -20, I also shot 20 dark frames at the same settings as my lights i also done 20 x flats and dark flats at 2.5 second exposures gain 120 and at -20.

I ran them through APP creating master dark, master flat and  master dark flat files also a bad pixel map, once APP done it thing the final image had lots of red and blue pixels in it, I tried stacking them gain but this time I tried sigma clipping but I ended up with the same result I even tried Windsor and MAD sigma clipping but I still had red and blue pixels in my image, even when I stacked just the light frames I still had red and blue pixels.

My friend has stacked them in Pixinsight and he gets the same issue.Can anyone help or have I got a faulty camera ?

Thanks.

 

Edited October 23, 2019 by daveangie0110

[Anthonyexmouth]

10 minutes ago, daveangie0110 said:

Hi all

Can anyone help.

I just purchased a ASI294MC Pro camera,  I tried it out for the first time on my Redcat and a UV/IR filter, from my very light polluted garden (Bortle 8-9) I shot 25 x 180 second exposures at 120 gain and -20, I also shot 20 dark frames at the same settings as my lights i also done 20 x flats and dark flats at 2.5 second exposures gain 120 and at -20.

I ran them through APP creating master dark, master flat and  master dark flat files also a bad pixel map, once APP done it thing the final image had lots of red and blue pixels in it, I tried stacking them gain but this time I tried sigma clipping but I ended up with the same result I even tried Windsor and MAD sigma clipping but I still had red and blue pixels in my image, even when I stacked just the light frames I still had red and blue pixels.

Can anyone help or have I got a faulty camera ?

Thanks.

post an image, also try stacking in DSS to see if it might be a setting issue in APP

[daveangie0110]

13 minutes ago, Anthonyexmouth said:

post an image, also try stacking in DSS to see if it might be a setting issue in APP

Hi,

I have now added the image.

[Anthonyexmouth]

how did you do your flats?

try stacking just the lights.  

 

[daveangie0110]

1 minute ago, Anthonyexmouth said:

how did you do your flats?

try stacking just the lights.  

 

I done my flat frames aiming for a value of 28000 ADU i used a tablet, i have tried stacking just the lights but still no good.

[Anthonyexmouth]

29 minutes ago, daveangie0110 said:

I done my flat frames aiming for a value of 28000 ADU i used a tablet, i have tried stacking just the lights but still no good.

ok, stack in DSS and post the unprocessed image that comes out. no stretching. 

[spillage]

Do your darks have the same issues?

[daveangie0110]

2 hours ago, spillage said:

Do your darks have the same issues?

No darks are fine.

[Anthonyexmouth]

does it only happen after stacking? 

 

[vlaiv]

Just a couple of points.

I'm having hard time identifying hot pixels in this image - star field is so dense that I'm never sure if it is hot pixel or the star.

Hot pixels will show in your darks - stretch your master dark and note position of hot pixels in it - they should roughly correspond to pixels in final image (there is some alignment in final image).

You can't really do cosmetic correction at this sampling resolution because stars are tiny so that is out of the question.

Did you dither your subs? If you plan to use sigma reject stacking you need your subs dithered properly - that means quite a shift because of sampling rate. If you move your sub by just a few arc seconds - that is no dither at all when your imaging resolution is about 4"/px.

[daveangie0110]

5 minutes ago, Anthonyexmouth said:

does it only happen after stacking? 

 

I stacked just the light frames and they are still in that image.

[Anthonyexmouth]

Just now, daveangie0110 said:

I stacked just the light frames and they are still in that image.

what about a single sub?

[daveangie0110]

5 minutes ago, vlaiv said:

Just a couple of points.

I'm having hard time identifying hot pixels in this image - star field is so dense that I'm never sure if it is hot pixel or the star.

Hot pixels will show in your darks - stretch your master dark and note position of hot pixels in it - they should roughly correspond to pixels in final image (there is some alignment in final image).

You can't really do cosmetic correction at this sampling resolution because stars are tiny so that is out of the question.

Did you dither your subs? If you plan to use sigma reject stacking you need your subs dithered properly - that means quite a shift because of sampling rate. If you move your sub by just a few arc seconds - that is no dither at all when your imaging resolution is about 4"/px.

If you zoom in to the image you can see lots of red and blue pixels, I had a friend of mine who run it through Pixinsight and he could see the pixels in the image. I streched the dark frames and they looked ok. I did not dither either.

I have all the FIT files in my dropbox which I can send you if you like.

[fwm891]

Probably NOT dithering you've strengthened the R/B pixels. Always good to dither as you break-up/even out the background noise.

[Anthonyexmouth]

7 minutes ago, daveangie0110 said:

If you zoom in to the image you can see lots of red and blue pixels, I had a friend of mine who run it through Pixinsight and he could see the pixels in the image. I streched the dark frames and they looked ok. I did not dither either.

I have all the FIT files in my dropbox which I can send you if you like.

yeah, post the link so we can look at the individual subs. 

[daveangie0110]

Here is the link to my dropbox.

https://www.dropbox.com/sh/aj8u1tleokryulp/AAARZXn5lWqK0sS69bfCefnUa?dl=0

The top file is where all my lights and calibration frames are in.

[Adam J]

21 hours ago, daveangie0110 said:

Hi all

Can anyone help.

I just purchased a ASI294MC Pro camera,  I tried it out for the first time on my Redcat and a UV/IR filter, from my very light polluted garden (Bortle 8-9) I shot 25 x 180 second exposures at 120 gain and -20, I also shot 20 dark frames at the same settings as my lights i also done 20 x flats and dark flats at 2.5 second exposures gain 120 and at -20.

I ran them through APP creating master dark, master flat and  master dark flat files also a bad pixel map, once APP done it thing the final image had lots of red and blue pixels in it, I tried stacking them gain but this time I tried sigma clipping but I ended up with the same result I even tried Windsor and MAD sigma clipping but I still had red and blue pixels in my image, even when I stacked just the light frames I still had red and blue pixels.

My friend has stacked them in Pixinsight and he gets the same issue.Can anyone help or have I got a faulty camera ?

Thanks.

 

Pixel rejection only works if you dither the subs, so did you dither the subs? Also thats not very much data so I think you need to collect at least 4 times the amount of subs before you can be justified in complaining about noise irrespective of the format.  

Adam 

[daveangie0110]

4 minutes ago, Adam J said:

Pixel rejection only works if you dither the subs, so did you dither the subs? Also thats not very much data so I think you need to collect at least 4 times the amount of subs before you can be justified in complaining about noise irrespective of the format.  

Adam 

Thanks Adam, it was only a test of my camera and I only managed 25 subs, would more subs stop the red and blue pixels ?

[Adam J]

Just now, daveangie0110 said:

Thanks Adam, it was only a test of my camera and I only managed 25 subs, would more subs stop the red and blue pixels ?

If you dither then yes. If you don't dither it will get worse. 

Adam

[alacant]

7 minutes ago, Adam J said:

have I got a faulty camera ?

Hi. Looks good to me. For just 180s frames, it's amazing. Nice to see so many stars;)

Keep going and I think you'll end up with a winner.

[daveangie0110]

40 minutes ago, alacant said:

Hi. Looks good to me. For just 180s frames, it's amazing. Nice to see so many stars;)

Keep going and I think you'll end up with a winner.

Thanks adam, if you look at one of the light frames you can see lots of red and blue pixels but I dont know why they are in my image 

[alacant]

2 hours ago, daveangie0110 said:

red and blue pixels

With 25 frames, that happens if you want to stretch to that extent.

Do another 25, but this time dither by about 6 pixels between each frame. Stack these with the remaining 25 using say, sigma clip 4:3. 

Cheers and good luck.

Edited October 24, 2019 by alacant
ES GB

[Rush]

Hi,

Reduce the gain, start from 60 or 70 instead of 120. Off set leave at default. Frames @180s or below.

Use an IR cut filter.

Cleaned up ur image without cali frames, Im allergic to cali frames 😩.

Hope this helps.

 

[Adam J]

2 minutes ago, Rush said:

Hi,

Reduce the gain, start from 60 or 70 instead of 120. Off set leave at default. Frames @180s or below.

Use an IR cut filter.

Cleaned up ur image without cali frames, Im allergic to cali frames 😩.

Hope this helps.

 

Never use a gain of less than 120 on the ASI294mc pro as it alters how it reads the pixels.

[geordie85]

Just a thought, have you tried stacking without using masters of your calibration frames and using the calibration subs?