Author Topic: The North America Nebula  (Read 6466 times)

Offline twade

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The North America Nebula
« on: 2007 November 20 20:54:29 »
To all,

This was a fun yet challenging area to process.  It really felt good putting all the things I learned in Juan Conejero's excellent Deconvolution and HDRWaveletTransform processing tutorial.  This is the result of median combining three 30-minute exposures taken through a 6nm AstroDon H-alpha filter using the Pentax 67 300mm lens and ProLine 16803 combination.  Calibration was done in Maxim DL.  L-R deconvolution, noise reduction, and stretching were done in PixInsight Standard.  The HDRWaveletTransform was used to control the wide dynamic range in the second example.  Since it is very easy, at least for me, to over-process a file using HDRWaveletTransform, I always use a mask to tame its results.  Finally, Photoshop CS3 was used to create the web versions.  I highly recommend looking at the higher resolution files.  They are well worth the wait.  Please, let me know which version you prefer.  

Personally, I'm torn between them.  On the one hand, I like the familiar brightness of the first example; however, the "controlled" version definitely shows the hotspots better.  I realize the second example may be approaching the over-processed realm, but there sure is a lot going on in this region of space.

First Example:
   1600x1600:
      http://tinyurl.com/2edx6m
   2400x2400:
      http://tinyurl.com/2woevz

Second Example:
   1600x1600:
      http://tinyurl.com/2u44aj
   2400x2400:
      http://tinyurl.com/yvhxc8

Enjoy,

Wade

Offline avastro

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The North America Nebula
« Reply #1 on: 2007 November 21 05:05:05 »
Hi Wade,
Very good data and excellent job in processing.
For my taste, the first example is a fine image with still a lot of data burried in it.
The second is a bit over processed something in between will be superbe.
Both are very good images of a region with a lot of Ha stuff.
Well done.

Antoine
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Offline LD

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The North America Nebula
« Reply #2 on: 2007 November 21 05:21:32 »
First of all, Wow! Great image either way, and that FOV is absolutely amazing with the camera and lens combination. Very rich star field as well, which I don't seem to think of with that region.

I'm a bit with Antoine on the "somewhere in the middle" comment, but I lean toward the second version. I think the HDRWavelets did help differentiate the structures in the major nebulas, not just the "wall" in "Mexico" which is what you usually get, but throughout showing off some structure you don't often see. I agree it is very easy to overwork HDRWavelets and lose the billowy nebulosity of the first image, but it is exciting to bring out all that detail.

Great image(s)!

Larry

Offline Jack Harvey

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Somewhere in the middle
« Reply #3 on: 2007 November 21 07:07:48 »
I frequently find myself in this dilemma and often find the solution in a blend.  Use Pixel math and first try a 50:50 blend and then try different percentages.

I will be waiting for the color version<G>
Jack Harvey, PTeam Member
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Offline Juan Conejero

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The North America Nebula
« Reply #4 on: 2007 November 21 12:49:33 »
Wade,

Fabulous image. I vote for the second version without doubt. In fact, as you know well, I'd go quite further with HDRWT for this image. Now you have all kinds of opinions  :lol:
Juan Conejero
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Offline twade

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The North America Nebula
« Reply #5 on: 2007 November 22 19:04:08 »
To all,

Thanks for all your kind words.  Within a day or so I'll have a new version.  I "messed" up the other one when I did a median combine rather than an average.  This should improve the SNR.

It appears version 1 has won the most votes with a few in between.  Is this because it is better or we're just more familiar with seeing it this way?  It amazes me just how much more detail a CCD records over film.  I believe over time, we will all get more familiar with the later version as we take our new medium to its limits as we did  with film in the past.

I enjoy all the images posted on this site.   Even though we all take the same targets, they all turn out different.  It's these differences that make our hobby so fulfilling.

Wade

Offline vicent_peris

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The North America Nebula
« Reply #6 on: 2007 November 23 00:22:56 »
Hi Wade,

congratulations on your new image.

My opinion: both images are under-processed.  :lol:

If you have bought a CCD camera, you MUST go to the limits of the camera. Period.

Also, I think you must process better the larger structures. Try to erase all the small structures (specially stars) with a morphological filter through a star mask, and after process the large scale image. Try a HDRWT with that image, you will get surprised.  :wink:  You can make too curves and wavelets transforms. For combining the result with the original image, I think it's better to have also a small scale "stressed" image; you can combine then, in PixelMath, the three images: raw, small scale and large scale, simply with a sume, and asigning a weight to each one: raw*k + ss*k + ls*k.


Good luck!
Vicent.

Offline David Serrano

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The North America Nebula
« Reply #7 on: 2007 November 23 00:23:42 »
FWIW, I'd go to a 1.8th version ;). That is, an in-between one definitely closer to the second, in which the nebula at the left is almost missing.
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 David Serrano

Offline Carlos Milovic

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The North America Nebula
« Reply #8 on: 2007 November 23 08:17:25 »
Hi Wade

Quote
It appears version 1 has won the most votes with a few in between. Is this because it is better or we're just more familiar with seeing it this way?


I think that the reason is the second you menctioned. Avoiding for a little while the matter of wich one is the best, I think that any time we see something different, we tend to dislike it at first sight. Now, in astrophotography, images are so basically processed, that they tend to be all similar-like. Only advanced imagers/astrophotographer are able give theyr own print to the target, and make it unique. We may like them or not, but it is different, and that creates an impact over us.
Now, in my opinion, we must push the data to its limits. Film photography has not been better the later years becouse of better emulsions... it was the digital processing that made the change. It is not a secret that it has been possible to achieve similar or better results with smaller telescopes, and that wide field has gone deeper than ever. So, in you case, you should not be happy with just the first image. It is too typical, too familiar, and has a lot in it to explote. As Vicent said, you should go a bit further, and put more effort in working the middle and large scales. Make the nebulaes use a larger dynamic range, with better contrast as result. Also it would look less "opaque".


Quote
It amazes me just how much more detail a CCD records over film. I believe over time, we will all get more familiar with the later version as we take our new medium to its limits as we did with film in the past.


True. But, keep in mind the even film was not pushed to its limits. Anyway, CCD returns better raw data, and is far easier to accumulate more time/shots. Also is easier to combine to perform high dynamic range images...  There is more freedom to explore.

Quote
I enjoy all the images posted on this site. Even though we all take the same targets, they all turn out different. It's these differences that make our hobby so fulfilling.


Yes. And you remember me of Richard Crips, how said in APML that he was bored becouse everything looked the same, so he wante to explore new methods to capture data. It is true, processing tends to be done in the same way, but this is our fault, becouse a) we don't push the data to it's limits, in all senses, b) we are more confortable with familiar lookings, or we follow a scheme "impossed" by the "masters" c) people is so obsesed with color calibration and "scientific looks" that they forget that this is an art form, and there are so many possibilities that are unexplored.
IMHO, we should not aim our processing to achieve a "real looking" image. Instead, we must work it to produce an impact on the people, and communicate the beuty of the universe. We must take advantage of the new tools, and play with the data, with the only restriction to be honest.
Regards,

Carlos Milovic F.
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