M33 last night (updated to add a 2nd night of data)

[StuartT]

6h 24min on M33 with my Esprit 150, ASI 2600MC and an Optolong L Pro filter (processed in Pixinsight from start to finish)

 

Edited October 6, 2022 by StuartT

[MarcuSmythe]

Looks lovely to me!

[The Lazy Astronomer]

That's nice. Looks very clean for just 3 and bit hours.

I think you may have some over correcting flats (inverse vignetting visible in the corners) and I wonder if there's a tad too much green in the blues?

[Stuart1971]

Beautiful rendition….love it….👏🏻👏🏻👍🏻

[StuartT]

11 hours ago, The Lazy Astronomer said:

 

I think you may have some over correcting flats (inverse vignetting visible in the corners)

Interesting. I wonder how that could have happened? Surely the flats are the flats (as in they are only showing what the optical train is), so what would be causing over-correction?

[The Lazy Astronomer]

3 hours ago, StuartT said:

Interesting. I wonder how that could have happened? Surely the flats are the flats (as in they are only showing what the optical train is), so what would be causing over-correction?

The joys of image calibration!

The first thing I would think it would be is improperly subtracted darks. Did you take darks (for the lights) and flat darks (for the flats)?

[StuartT]

1 hour ago, The Lazy Astronomer said:

The joys of image calibration!

The first thing I would think it would be is improperly subtracted darks. Did you take darks (for the lights) and flat darks (for the flats)?

yep. I used a master dark, 20 flats and 20 darkflats

[Mark at Beaufort]

Beautiful image - very well done. 

[Ouroboros]

Very nice @StuartT.  Lots of lovely detail there.  It’s maybe a bit colour saturated for my taste but then that’s personal choice. The stars are in nice proportion to the nebular. Did you have to do any star reduction of does the filter do that for you? Nice anyway. 

Tecnical question. As a fellow owner of an ASI2600MC do you attach the Optolong L Pro filter on the front of the camera and then the spacers to that?  Is it the 1.25” filter version? 

[tomato]

Great result, lots of detail from less than 4 hrs of integration. The inverse vignetting is easily fixed in post processing, not sure how you do it in PI, but the bundled Win 10 photo editor has a tool for it.

[StuartT]

2 hours ago, Ouroboros said:

Very nice @StuartT.  Lots of lovely detail there.  It’s maybe a bit colour saturated for my taste but then that’s personal choice. The stars are in nice proportion to the nebular. Did you have to do any star reduction of does the filter do that for you? Nice anyway. 

Tecnical question. As a fellow owner of an ASI2600MC do you attach the Optolong L Pro filter on the front of the camera and then the spacers to that?  Is it the 1.25” filter version? 

Thanks. I generally do most of the processing on the starless image and then add the stars back in at the end using Pixel Math (generally I multiply the stars by 0.7 or 0.8 to reduce their emphasis a bit)

My optical train is Esprit 150 (native) --> spacer --> 2" filter --> OAG --> camera

[tooth_dr]

7 hours ago, StuartT said:

Interesting. I wonder how that could have happened? Surely the flats are the flats (as in they are only showing what the optical train is), so what would be causing over-correction?

Target ADU in your flats can make a difference.

[The Lazy Astronomer]

4 hours ago, StuartT said:

yep. I used a master dark, 20 flats and 20 darkflats

Light leak? (in either the darks or flat darks) - would only have to be very slight to make a difference

How old is the master dark? 

Gain and/or offset inadvertently changed? 

I vaguely recall something with APT's flat wizard where it did something weird which made flats overcorrect, but I think I've seen you use NINA right? So probably not that. 

I've not heard of the 2600 being particularly fussy (unlike my 294...😑), but I temperature match all my frames. Might help for future if you don't already (certainly won't hurt in any case).

[StuartT]

 

9 minutes ago, The Lazy Astronomer said:

Light leak? (in either the darks or flat darks) - would only have to be very slight to make a difference

I wouldn't think so. My flat darks are always done at night and my darks were done with the camera in a bag

9 minutes ago, The Lazy Astronomer said:

How old is the master dark? 

Gain and/or offset inadvertently changed? 

Not very. It's only from May this year. Nope, same gain and offset.

9 minutes ago, The Lazy Astronomer said:

I vaguely recall something with APT's flat wizard where it did something weird which made flats overcorrect, but I think I've seen you use NINA right? So probably not that. 

I've not heard of the 2600 being particularly fussy (unlike my 294...😑), but I temperature match all my frames. Might help for future if you don't already (certainly won't hurt in any case).

Yes, I only ever use NINA and the flat wizard is great.

This time the temperature was higher for the flats and dark flats (because I accidentally disconnected the camera before remebering to do my flats (it was 3:30am 🥱) so when I re-connected it to do them, the camera had warmed back up (from -15C to about +9C). Maybe that was it?

Edited October 4, 2022 by StuartT

[The Lazy Astronomer]

30 minutes ago, StuartT said:

Maybe that was it?

That could well be it, especially if you've seen no issue on previous (fully temperature matched) images. 

On another note, I recently happened upon some nifty pixelmath for removing and re-adding stars on the pixinsight forums: https://pixinsight.com/forum/index.php?threads/unscreening-and-re-screening-recombining-stars-with-starless-images.18602/

Probably already a well known technique to some, but it helped me, so thought I'd share. 

[tooth_dr]

16 minutes ago, The Lazy Astronomer said:

That could well be it, especially if you've seen no issue on previous (fully temperature matched) images. 

On another note, I recently happened upon some nifty pixelmath for removing and re-adding stars on the pixinsight forums: https://pixinsight.com/forum/index.php?threads/unscreening-and-re-screening-recombining-stars-with-starless-images.18602/

Probably already a well known technique to some, but it helped me, so thought I'd share. 

This is why I own a copy of PI but haven’t used it.  It looks amazing but my head can’t round it even to get started 

[Stuart1971]

2 hours ago, tooth_dr said:

This is why I own a copy of PI but haven’t used it.  It looks amazing but my head can’t round it even to get started 

I felt exactly the same and have used APP for years, but in the summer I got PI spent a good few hours on YouTube and watched a load of videos, the best ones being from Adam Block, and then got started, TBH I found it very intuative and it seemed to really suit my way of thinking, now after a couple of months I would not use anything else, and unlike before PI, I actually look forward to processing now and am not phased by the thought of it…

Am really glad I spent the time on your tube, Lukamatico on YT is very good and he has just started a set of videos for pure beginners, and Adam Block for the more in depth stuff, he is a real PI master…

Edited October 4, 2022 by Stuart1971

[tooth_dr]

41 minutes ago, Stuart1971 said:

I felt exactly the same and have used APP for years, but in the summer I got PI spent a good few hours on YouTube and watched a load of videos, the best ones being from Adam Block, and then got started, TBH I found it very intuative and it seemed to really suit my way of thinking, now after a couple of months I would not use anything else, and unlike before PI, I actually look forward to processing now and am not phased by the thought of it…

Am really glad I spent the time on your tune, Lukamatico on YT is very good and he has just started a set of videos for pure beginners, and Adam Block for the more in depth stuff, he is a real PI master…

Cheers Stuart, that is encouraging and sums it up well 👍🏻

[Stuart1971]

57 minutes ago, tooth_dr said:

Cheers Stuart, that is encouraging and sums it up well 👍🏻

Give it a try, and let us know how you get on….👍🏻

[Ouroboros]

13 hours ago, StuartT said:

Thanks. I generally do most of the processing on the starless image and then add the stars back in at the end using Pixel Math (generally I multiply the stars by 0.7 or 0.8 to reduce their emphasis a bit)

My optical train is Esprit 150 (native) --> spacer --> 2" filter --> OAG --> camera

OK. Thanks. Your method certainly seems to work. 

[StuartT]

12 hours ago, The Lazy Astronomer said:

On another note, I recently happened upon some nifty pixelmath for removing and re-adding stars on the pixinsight forums: https://pixinsight.com/forum/index.php?threads/unscreening-and-re-screening-recombining-stars-with-starless-images.18602/

Probably already a well known technique to some, but it helped me, so thought I'd share. 

To remove the stars I just use StarXTerminator in Pixinsight. The latest version works incredibly well and is fast if you use your GPU. Then I just re-add the stars with the simple PixelMath expression

$T+0.8*stars

or similar

 

12 hours ago, tooth_dr said:

This is why I own a copy of PI but haven’t used it.  It looks amazing but my head can’t round it even to get started 

Oh boy, you must learn PI! It's absolutely fantastic. Game changing. I don't use any other software now from raw data all the way to final image. The Adam Block courses are well worth it.

Edited October 5, 2022 by StuartT

[DaveS]

15 hours ago, tooth_dr said:

This is why I own a copy of PI but haven’t used it.  It looks amazing but my head can’t round it even to get started 

I'm with Adam on this. I had the trial version but it just , so for what passes for my sanity I went back to using AstroArt which just keeps getting more powerful, and is now at V8 sp2.

[StuartT]

5 hours ago, DaveS said:

I'm with Adam on this. I had the trial version but it just , so for what passes for my sanity I went back to using AstroArt which just keeps getting more powerful, and is now at V8 sp2.

I do totally understand that. PI is rather 'its own thing' and I was put off it for a while thinking "I don't need that" "too complex" etc. But then I took the plunge and it's been a massive game changer for me. But ultimately, each to his/her own. The best results come not from the tools but from the user of the tools.

[The Lazy Astronomer]

On 05/10/2022 at 10:19, StuartT said:

To remove the stars I just use StarXTerminator in Pixinsight. The latest version works incredibly well and is fast if you use your GPU. Then I just re-add the stars with the simple PixelMath expression

$T+0.8*stars

That formula can work, it depends how the stars only image was created.

The post I linked to explains how to unscreen stars using starnet (I think the latest version of starX has an option to create an unscreened star image automatically). The pixelmath

~((~starless)*(~stars))

is used later to add the stars back in

Edited October 6, 2022 by The Lazy Astronomer

[StuartT]

3 hours ago, The Lazy Astronomer said:

That formula can work, it depends how the stars only image was created.

The post I linked to explains how to unscreen stars using starnet (I think the latest version of starX has an option to create an unscreened star image automatically). The pixelmath

~((~starless)*(~stars))

is used later to add the stars back in

Starnet2 and StarX both have the same options. You can either simply remove the stars, or you can remove them and generate a star only image too. I always do the latter, then I fiddle about with the starless image (deconv really only works well on a starless image for example), then when I'm happy I add the stars back. Being a simple man 😉, I just use addition, but I'm going to try your rather fancier equation next time. Actually I have some data in the oven now, so I'll try this when it's cooked.

(I am using the latest version of StarX btw - AI 11 - and it's now clearly superior to Starnet2)

Edited October 6, 2022 by StuartT