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M31


tooth_dr
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Coupled with good optics, these new sony-based CMOS cameras are pretty incredible.  I am impressed for just 60 minutes of data.  I'm trying to gather more and some Ha, so this is just a quick workup of the data.

APM LZOS 105/650

RICCARDI 0.75x REDUCER

ZWO 2600MC

IDAS P2 LPF

MESU e200

30 x 120s subs

SG PRO / APP / PS

 

 

CS
Adam

 

M31-60min-OSC-P2.thumb.jpg.210a0dc7aa9f086d01cca3263286e849.jpg

 

 

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9 hours ago, ONIKKINEN said:

Amazing, and just an hour.

What sort of sky quality was this shot from? 

Thank you, it holds up well even at full resolution.

Im in a Bortle 4 according to maps.  I live in a rural area, but unfortunately there are a number of LED lights in some houses around 400-800 yards away.

I was experimenting with a LPF because typically I image south over the nearby town 5 miles away, and there is a good old bit of sky glow.  I also have a clear filter that I intend to also try as a comparison.  I think I'll try a few subs on this with the clear filter next.

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8 hours ago, symmetal said:

Great image for just an hour Adam. The noise, while evident isn't the blotchy type which can spoil some cmos images without a longer integration time. The benefit of a 16 bit camera. 😊

Alan

Thanks Alan.  Its definitely got some grain, but I didnt do any noise reduction at all on the image.  I'm been using FLATS, DARK FLATS, DARKS and BIAS, and didnt dither.

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2 minutes ago, tooth_dr said:

Thanks Alan.  Its definitely got some grain, but I didnt do any noise reduction at all on the image.  I'm been using FLATS, DARK FLATS, DARKS and BIAS, and didnt dither.

Can I ask, is there a need for Bias as well as dark flats, as I read with CMOS then Dark flats are the best and only one needed, along with Darks and Flats…?

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28 minutes ago, Stuart1971 said:

Can I ask, is there a need for Bias as well as dark flats, as I read with CMOS then Dark flats are the best and only one needed, along with Darks and Flats…?

I’m not sure. There is disagreement about it, and I’ve tried various combinations and can’t really see much difference.  There are subtle differences I am sure but I can’t physically see them and my processing probably isn’t skilled enough to take advantage of them.  It doesn’t seem to be detrimental using bias so I just continue out of habit as I did with my CCD.  

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Very nice Adam, certainly impressive for an hour, I was similarly impressed by the camera's performance when I took 30 mins of M31 through my GT71...   As to the Darks and Bias question...  I just measured my Bias it was 500.6 with a MAD of 0.6  my 300 sec Dark was 501.2 with a MAD of 1.0 with the difference being the 'snowstorm' of hot pixels...   I'd say matched Darks as they'll best remove the Hot Pixels... dithering though is better still ;) 

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Just now, Laurin Dave said:

dithering though is better still

Cheers Dave.  Just need to work out the order.  I'm taking 2 minute subs with the OSC, and it is the main system that does plate solving and dithering, and the other scope does 5 minute NB subs.  So with dithering at it's current configured, even if I do every fifth sub, I'm going to lose half of my NB subs.

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Just now, tooth_dr said:

Cheers Dave.  Just need to work out the order.  I'm taking 2 minute subs with the OSC, and it is the main system that does plate solving and dithering, and the other scope does 5 minute NB subs.  So with dithering at it's current configured, even if I do every fifth sub, I'm going to lose half of my NB subs.

I'd just experiment with how frequently you dither.  My main scope has the CCD so its either 10 or 20 min subs... once I've got 5 or 6 dithers in an integration they combined with cosmetic correction sorts out any remaining hot pixels...  So I'd start by just spreading 5 or 6 dithers over however long you're imaging for...  So over say 3 hours do them every 15 subs or so...  If you ar ein attendance when it dithers or focuses you can always restart the NB sub (or at least you can in SGPro)...

Unfortunately my camera needs a window clean...  although it doesn't look like the grease issues some have had..  

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36 minutes ago, Laurin Dave said:

I'd just experiment with how frequently you dither.  My main scope has the CCD so its either 10 or 20 min subs... once I've got 5 or 6 dithers in an integration they combined with cosmetic correction sorts out any remaining hot pixels...  So I'd start by just spreading 5 or 6 dithers over however long you're imaging for...  So over say 3 hours do them every 15 subs or so...  If you ar ein attendance when it dithers or focuses you can always restart the NB sub (or at least you can in SGPro)...

Unfortunately my camera needs a window clean...  although it doesn't look like the grease issues some have had..  

That's a pretty reasonable idea, I'll aim for at least 5 dithers in total.

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