NGC 7822 3 panel mosaic (Ha)

[Rodd]

Manually framed using FSQ 106 with .6x reducer and the ASI 1600 with 3um Astrodon Ha filter.  The top and bottom panels were collected in 1 night during a 100% full Moon, and the middle panel was collected during an approximately 75% Moon.   It could use more data--especially the bottom panel.   A fun project for Moonlit nights                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Top Panel: 30 5min subs

Middle Panel: 37 5 min subs

Bottom Panel: 32 5min subs

Edit: Wow, full resolution is BIG!

 

[symmetal]

Great image Rodd. It looks like a sad skull shedding a tear. 

I notice at full resolution it exhibits a course blotchy noise on the background which my ASI1600 shows too. It's a feature of stretching 12 bit data I suppose. I was thinking whether to experiment adding a small amount of high frequency black noise to the 16 bit image in Photoshop before each stretch to see if it can disguise the blotchiness. Similar to dithering signals before digitizing to increase the A-D resolution.

Alan

 

[Sunshine]

Very beautiful image, so sharp! your guiding must be spotless.

[Rodd]

38 minutes ago, symmetal said:

Great image Rodd. It looks like a sad skull shedding a tear. 

I notice at full resolution it exhibits a course blotchy noise on the background which my ASI1600 shows too. It's a feature of stretching 12 bit data I suppose. I was thinking whether to experiment adding a small amount of high frequency black noise to the 16 bit image in Photoshop before each stretch to see if it can disguise the blotchiness. Similar to dithering signals before digitizing to increase the A-D resolution.

Alan

 

Thanks Alan.  It just needs more data.  And, the Moonlight plays havoc, even with 3um Ha.  That as well as...the full resolution viewing is WAY pat what this image should be viewed at!

Rodd

[Rodd]

14 minutes ago, Sunshine said:

Very beautiful image, so sharp! your guiding must be spotless.

Thanks Sunshine.  M guiding is typically pretty good.  At 318mm, it is pretty forgiving!

Rodd

[Rodd]

Here is the image down-sampled a bit so full resolution viewing is a bit better.

Edit:   I could even go further, but I like to have a fairly close in look--its keeps me honest with respect to noise control and sharpening--for upon zoom is where the effects of over processing rear their ugly heads.  The first post was just too close.  Every imag break down at some point!

[symmetal]

52 minutes ago, Rodd said:

Thanks Alan.  It just needs more data.  And, the Moonlight plays havoc, even with 3um Ha.  That as well as...the full resolution viewing is WAY pat what this image should be viewed at!

Rodd

Yes, you're right. The moon does add some peculiar noise features.

48 minutes ago, Rodd said:

Here is the image down-sampled a bit so full resolution viewing is a bit better.

Edit:   I could even go further, but I like to have a fairly close in look--its keeps me honest with respect to noise control and sharpening--for upon zoom is where the effects of over processing rear their ugly heads.  The first post was just too close.  Every imag break down at some point!

Yes, I like that size.  I didn't mean to criticise your original image although it might have come across that way.  I tend to examine them too closely. I expect it's from my 35 years working as a TV studio engineer where one part of the job was examining TV camera outputs, sitting a few inches from a monitor during recordings colour matching the camera outputs, and looking for any technical picture problems. 

I wish my images were that sharp at the corners. 

Alan

[Rodd]

3 minutes ago, symmetal said:

I didn't mean to criticise your original image although it might have come across that way

Please, criticize all you like, Alan.  The truth hurts, but truth is truth and the goal is to create as high quality images as possible. I appreciate you taking the time to inspect the posts.    It can only work to foster improvement!

Rodd

[MikeODay]

Lovely image - I really like the composition.

[Rodd]

16 minutes ago, MikeODay said:

Lovely image - I really like the composition.

Thanks Mike.  A peculiar target. 

Rodd

[Rodd]

1 hour ago, MikeODay said:

Lovely image - I really like the composition.

Thanks Mike.

Rodd

[Rodd]

Here is a version that is reduced a bit more and is pushed less so the background in the bottom panel is less problematic.  There is more noise control, but not terribly too much.

 

 

[Allinthehead]

Very nice Rodd. You seem to be have that Asi/Tak combination singing.

[Rodd]

5 hours ago, Allinthehead said:

Very nice Rodd. You seem to be have that Asi/Tak combination singing.

Thanks Richard.  Still working on the corner star deformity--the consensus is a 1mm or so spacing issue.  Data is being looked at by TAK and my vendor to verify that it is not something with the reducer or scope (heaven forbid),  It can't be the camera as the stars are perfectr in teh TOA 130.  Its not terrible--I can live sith it for a time,  

Rodd

[Rodd]

I did not know if I wanted to pursue this mosaic or not, the bottom seeming to be a mess.  But last night I collected an hour of bottom panel subs, and the structures are beginning to take form.  Still need several hours I think, but the bottom of this mosaic may turn out to be almost as interesting as the middle portion.  My enthusiasm to complete, at least as a bi-color, has been rekindled.  May even need a more panels.

[Rodd]

Well--I think I will continue with the mosaic.  Here is a stand alone bottom panel--86 5min subs.  This  very interesting region, with allot of dark structures, but the nebulosity between the ball and the bottom of NGC 7822 is very dim, requiring allot of data.  A long focal length image of the circle would be interesting.  Maybe I need even more data.  Looking for that talc smooth look.  Maybe the Moon did effect the data.  But there is a huge difference between the bottom panel nd the middle panel--which is the typical target.  The 2 FOVs are in the same part of the sky images on the same night with the same equipment, and the difference in data quality is striking.  

 

[wimvb]

Great image Rodd. That is quite some effort you put in it. I hope you get some clear moonless nights to gather more data.

[Rodd]

59 minutes ago, wimvb said:

Great image Rodd. That is quite some effort you put in it. I hope you get some clear moonless nights to gather more data.

Thanks Wim.  The Moon is starting to shrink.  

Rodd

[gorann]

Yes, very nice and detailed image showing that you really have some good data and know how to swing it. I look forward to see the final version with colour. It could very well be the ultimate version of this great question mark in the sky.

[Rodd]

3 hours ago, gorann said:

Yes, very nice and detailed image showing that you really have some good data and know how to swing it. I look forward to see the final version with colour. It could very well be the ultimate version of this great question mark in the sky.

Thanks Gorann.  I hope I have the fortitude to see it through.  I will probably shoot OIII next and if the HOO bicolor is decent, may leave it at that.  Not sure.  I do like the Hubbell palette for this target.

Rodd

[swag72]

It's worth looking at a pane lower again.... there's CTB1 under there  

[Rodd]

32 minutes ago, swag72 said:

It's worth looking at a pane lower again.... there's CTB1 under there  

I figured there was something there--not sure I have the staying power to add a panel though.  That would be one long thin image.

Rodd

[wimvb]

10 minutes ago, Rodd said:

That would be one long thin image.

Yeah, but what a wall cover that would make. ?

[Adam J]

On 27/07/2018 at 22:16, symmetal said:

Great image Rodd. It looks like a sad skull shedding a tear. 

I notice at full resolution it exhibits a course blotchy noise on the background which my ASI1600 shows too. It's a feature of stretching 12 bit data I suppose. I was thinking whether to experiment adding a small amount of high frequency black noise to the 16 bit image in Photoshop before each stretch to see if it can disguise the blotchiness. Similar to dithering signals before digitizing to increase the A-D resolution.

Alan

 

The reality is that you need 100 subs per frame for exactly this reason, it reduces the quantization noise. Hence why I have been going for slightly shorter subs but more of them in my own testing.

[Rodd]

8 hours ago, Adam J said:

The reality is that you need 100 subs per frame for exactly this reason, it reduces the quantization noise. Hence why I have been going for slightly shorter subs but more of them in my own testing.

Well, the last image has 86--somehow I don't think 500 will solve the problem.  I tried Sh2-119 in red and collected 219 subs--too dim, and blotchy, then I tried 60 sec subs--still too dim and blotchy.  Finally I tried Ha and the bright areas come out well with 5min subs--M16 and M17 came out well with 30-40 subs,  but dimmer targets don't fare well.  M8/M20 came out good in LRGB with 30 sec subs and about 100-130 subs per channel.  So I think it is target dependent. I think the blotchiness in the background here is a combination of conditions (biggest blood Moon in the last 100 years or something--100%-absolutely full to the brim), as well as me stretching to aggressively, which is a bad habit of mine  (probably trying to emulate one of Olly's deep masterpieces).  I backed off the stretch a bit and finished the mosaic in Ha.  The count is top panel 30 subs, middle panel 63 subs and the bottom panel 86 subs.  Note the  smoothness of the middle panel--with only 62 subs.  The top only has 30 and it is passable (actually the middle panel overlies the top so not much there but the upper background).  I know its just a band aide, but it stops the bleeding.  I have had trouble with LRGB in my skies (getting better as of late), and now with this camera, occasionally run into this background blotchiness.  It can't be the sky, because the middle panel and the bottom panel were shot on the same night, same conditions.  That's why I think its target dependent.

 

As an aside, because I dither, and there is a 15 second delay (or unknown cause) between sub download and themy guider settling pause (which is set only at 10 sec), it actually takes me MUCH longer to shoot an hours worth of 30 sec subs vs an hour of 5min subs.  Anyway, is this image better? BTW--I should downsample my images before uploading--the full resolution viewing for this image is just way too close--I usually try to process so that the image passes muster even at full resolution, but sometimes I fail at that.