NGC 2237 now in colour

[alexbb]

Hello all,

I just got the O3 and the S2 filters this weekend after 2 months of waiting. I bought initially an Optolong Ha and I thought to buy the O3 and S2 also from Optolong. They O3 and S2 are advertised as being 6.5nm which also contributed to go for them instead of the Baader's.

Anyway, I acquired some 3 hours if I remember well with the Ha in 1min subs and now just above 2 hours with the O3 in 3min subs. Unfortunately, I can image to the south only up to ~130 degrees in AZ. So the good skies around 180 degrees where objects reach the max altitude are not reachable from home. I have to give it a try later in spring from outside.

All taken with the ASI 1600 MMC, cooled to -15C, put on the Tair3s wide opened at F/4.5. 300mm focal length.

https://drive.google.com/open?id=0ByhJ_xuQxcnjWUZUZTRyRXFYYzA

Will post in the evening the Ha and the O3 components which were mixed HaOO.

Clear skies,

Alex

[wimvb]

Looks great. Nice framing, lovely colours, and beautiful detail.

[alexbb]

Just now, wimvb said:

Looks great. Nice framing, lovely colours, and beautiful detail.

Thanks! I see now that I should have rotated the O3 layers a little more clockwise. To the right side they appear a little misaligned. I manually scaled and rotated the O3 layer around the brighter star from the top-left. GIMP with measure tool and rotate instead of Registar. Sometimes I use Iris for this, but not this time. I hope I can get tonight one more hour with the O3 and I will need to reprocess it after this, of course.

[Filroden]

Your OIII subs have really added a nice dimension to this. I like it

[wimvb]

6 minutes ago, moise212 said:

Thanks! I see now that I should have rotated the O3 layers a little more clockwise. To the right side they appear a little misaligned. I manually scaled and rotated the O3 layer around the brighter star from the top-left. GIMP with measure tool and rotate instead of Registar. Sometimes I use Iris for this, but not this time. I hope I can get tonight one more hour with the O3 and I will need to reprocess it after this, of course.

Couldn't see that on my mobile.

Hope you get clear skies

[alexbb]

9 minutes ago, Filroden said:

Your OIII subs have really added a nice dimension to this. I like it

Thanks! I hope I can get some S2 too at some point.

3 minutes ago, wimvb said:

Couldn't see that on my mobile.

Hope you get clear skies

Couldn't see that either last night on my laptop. Thanks, clear skies too! Mostly fog here lately, but sometimes is not that much. Better than totally cloudy.

[simmo39]

Wow! v nice.

[alexbb]

3 hours ago, simmo39 said:

Wow! v nice.

Thank you!

I wonder if I should be greedy and try the S2 instead of continuing with the O3..

If you have the correct answer, please don't hesitate to tell me as I have only half an hour left to decide.

[PatrickGilliland]

Great first outing for new filters, Not a bicolour expert so will pass on palette specifics but nice image thus far.

Paddy

[alexbb]

Thanks, Paddy!

O3 seems to be the appropriate answer for this evening too.

[MartinB]

Well done Alex that is a lovely bicolour Rosette.  That Tair lens looks like a great performer.  

[alexbb]

Thank you, Martin! The Tair lens is certainly interesting mostly for the Ha. I don't find it as sharp for the O3, I don't know why, but it could be due to seeing. I doubt it though that it's that much. It appears for me that it has a pretty flat field (it was designed for 35mm film though) so it's pretty nice. But sometimes I get elongated stars, perhaps the front element doesn't stay parallel with the last element and the sensor, depending if I focus in or out. But it was way cheaper than the Esprit I'm thinking of.

[alexbb]

As promised, here are the Ha and O3 components, each of them just stretched and then processed. You can see the horrible gradients that I had to deal with.

If any of you is interested to process the raw stacks, I can provide them as tiffs or fits.

[PaulB]

That is really good,

I am beginning to like these cameras.

[AKB]

2 hours ago, moise212 said:

If any of you is interested to process the raw stacks, I can provide them as tiffs or fits.

Fits would be great.... just learning the basics of AP processing.  The best I can do with your Ha and O3 JPEGS from above is this (uncropped, the images don't seem to entirely overlay?)  Processed in Nebulosity:

[alexbb]

This is all for tonight:

HOO result and Ha and O3 layers aligned.

I'll attach also the original Ha and O3 stacks. If anyone interested, please. I had enough for a while...

Clear skies,

Alex

Ha_x3.tif

O3_x3.tif

[AKB]

@moise212  Thanks again for making these data available.  I'm wondering if you can comment on the processing?  Whilst I can get passable results by combining your processed Ha and O3 images, I'm having more difficulty with the raw stacks.

As you said, the LP is a bit of an issue.  In generating synthetic backgrounds, I see something which also looks like vignetting, so I'm wondering if your pre-processing included flats?  I'm also assuming that these are cropped out of a much larger image. 

Attached is the Ha and my synthetic background, side-by-side, on the same scale (clipped, linear).  Does this look at all correct... I'm wondering what yours looked like?  Thanks for any suggestions.

[alexbb]

9 hours ago, AKB said:

@moise212  Thanks again for making these data available.  I'm wondering if you can comment on the processing?  Whilst I can get passable results by combining your processed Ha and O3 images, I'm having more difficulty with the raw stacks.

As you said, the LP is a bit of an issue.  In generating synthetic backgrounds, I see something which also looks like vignetting, so I'm wondering if your pre-processing included flats?  I'm also assuming that these are cropped out of a much larger image. 

Attached is the Ha and my synthetic background, side-by-side, on the same scale (clipped, linear).  Does this look at all correct... I'm wondering what yours looked like?  Thanks for any suggestions.

Your welcome!

I've included darks, bias, flats, dark flats. But I took them only once, perhaps either at the beginning and I opened the setup and some dust got there after, either at the end and some dust was there and I cleaned when I opened it. I know that my flats seem not to have any dust on them.

They might be cropped, but not by much.

If I remember well, I combined 1 image wiped with StarTools (can't save the synthetic background) and another 1 wiped manually in GIMP.

Perhaps are much better ways to do this, but I'm doing it like this:

1. Crop a few pixels from the edge where are still some stacking artifacts.
2. Stretch the image to a level where I can see pretty well the details, but I'm careful to avoid clipping it.
3. Duplicate the stretched layer in order to be used as the gradient I want to remove.
4. Use the clone tool to replace the features and bright stars with a background area from around.
5. Use the smudge and heal tools to make the modified areas look uniform.
6. Repeat steps 3, 4, 5 for a few times and then combine them when the result looks uniform.
7. Use the gradient layer resulted by blending it with the stretched image in the Grain Extract mode.

Bring the background level to a decent value.
Import the image wiped in StarTools (this also had the dust areas fixed).
Blend the 2 images by getting their background values to about the same value, use masks for the dust motes.

Bring the result in StarTools and continue processing it there (HDR, sharpen, noise reduction, star repair and star reduction)

This is for the Ha layer. For the O3 layer, I didn't have a change to wipe it ok with StarTools, but, fortunately, I cleaned the dust properly before putting all together. I could manually wipe it better as described in the steps 1-7 above.

I can try to reprocess the Ha again at some point and note the steps I follow and save the intermediate results, but I don't think that I can do this before the weekend.

Clear skies,

Alex

[AKB]

Oh, wow!  Thanks for the comprehensive explanation!  I wasn't complaining at all, just trying to understand the process.  That looks quite labour intensive.  I was hoping for a more automated method!

I don't use StarTools or GIMP (perhaps I should) or PS or PI, for that matter.  Mostly just Nebulosity plus a bit of 'pixel math' in Matlab.

But thanks so much again.

 

[alexbb]

I'm afraid I don't know a more automated method, though the defaults used with the PixInsight's DBE may give you better faster results. I'm almost certain that you can achieve better results with DBE, but it needs some tweaking. I didn't want to invest more time to learn PI. I will probably do this at some point in the future.

Your welcome, I hope that any of what I said was helpful.

Clear skies!