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bryansay
super member
Reged: 02/25/09
Posts: 111
Loc: Georgetown, TX
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Here is my first serious attempt at Orion. Once again I am stumbling on the processing and would appreciate feedback from the group. I am using a crude blending technique to create high dynamic range. I am struggling to develop a lighter touch on processing.
Canon 40D Modified
Orion ED80 with Zhumell Skyglow Filter
HEQ-5 Mount, Starshoot Autoguider, Orion ST-80
From Driveway, Georgetown TX
October 18, 2009
Exposure: 10x15s + 10x30s + 20x60s + 10x 120s ISO1600 (47 Minutes total)
Darks, Flats, Bias
Stacked in IP3; Processed in PS
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Bryan Sayler
Celestron C9.25; Orion ED80
HEQ-5; Orion ST-80 w/starshoot
Nikon D80; Canon 40D Hap Griffin Mod
Empty Wallet 
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David Pavlich
Postmaster
Reged: 05/18/05
Posts: 8682
Loc: Mandeville, LA USA 30.22 X 90....
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NIce image, Bryan!!
David
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Proud Member; PAS NOLA,
"If we knew what we were doing, it wouldn't be called research..."
A. Einstein
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Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3453
Loc: Santa Cruz Mountains , CA
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I would say thats a really good job at blending , much better then my first few attempts.
A fine M42 Bryan , well done.
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Erik
Orion Atlas Self Hypertuned (EQMOD)
Orion ED 80
Williams Optics VII reducer
Celestron 8" SCT
Orion Starshoot Autoguider
PHD guide
Canon 400D Hap Griffin Mod w/Baader filter
Astronomik clip-in LP filter and 12nm Ha
Stilleto CVF and Bahtinov mask
Tamron 75-300mm&28-80mm lenses
NexImage webcam
http://www.flickr.com/photos/31986095@N05/
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jmX
super member
Reged: 04/23/09
Posts: 170
Loc: Orange County, CA
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I like it, except I think the m42 core looks strange because we all know it is much much brighter than that. I know people constantly chant "dont blow the core", but for something that bright it needs to be at least brighter than what you have already. I actually prefer it slightly blown out, because it looks *right*. Wouldn't expect to see sunspots in a regular sunset photo would you? No, the sun would be blown.
Also I think you could stretch the bottom end of your 2 minute exposure data to get the rest of the dusty parts of the nebula on the outskirts of M42...2 minute subs should have provided a bit of that for ya. I got a lot even in my 30 second subs actually.
Anyway, the colors are great, and aside from the really dark core it looks pretty darn natural and not overprocessed looking.
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Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
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RickShelton
member
Reged: 08/20/09
Posts: 22
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Quote:
Also I think you could stretch the bottom end of your 2 minute exposure data to get the rest of the dusty parts of the nebula on the outskirts of M42...2 minute subs should have provided a bit of that for ya. I got a lot even in my 30 second subs actually.
Not trying to highjack the thread, but could you elaborate on that "stretcthing" bit? I am new to processing or trying to and would like to learn the stretctching aspect of it.
Thanks,
Rick
Nice image btw.
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jmX
super member
Reged: 04/23/09
Posts: 170
Loc: Orange County, CA
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Stretching is where you take a range of intensities and expand those intensity values to a new, larger range. It also has the effect of increasing contrast in that range of intensity values. In this way, you can take very faint things that live down in the dark regions of an image, and stretch those dark intensity values. Also, at the same time, you're *NOT* stretching the values up at the top of the histogram, where the bright stars are, since they are already nice and bright, and would look unnatural and harsh if they were stretched much.
This is all done using the "curves" tool on the image histogram. Photoshop has this, the gimp has this, and I'm sure some of the astroimaging tools (dss, nebulosity, etc...) have this.
If you google for "curves" and "astrophotography" im sure somebody has explained this in much more detail out there on the web.
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Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
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drksky
super member
Reged: 09/01/09
Posts: 115
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This may sound like a dumb question, but how did you get diffraction spikes with a refractor?
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Tony C
AT8RC
C6-R
CG-5 ASGT
ST80 w/StarShoot Autoguider
Canon EOS 450D (Stock)
The Drinking Bird
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Tonk
Post Laureate
Reged: 08/19/04
Posts: 4358
Loc: Leeds, UK, 54N
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Quote:
This may sound like a dumb question, but how did you get diffraction spikes with a refractor?
Use a pair of crossed threads across the objective or use Noel's photoshop filter if you have forgotten the threads
Also a Tony C !
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Televue 85, GM-8/Gemini, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB)
Coronado SM60/BF10, Baader Herschel Wedge
Leeds Sky Clock Ripon Sky Clock
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Tonk
Post Laureate
Reged: 08/19/04
Posts: 4358
Loc: Leeds, UK, 54N
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Quote:
Stretching is where you take a range of intensities and expand those intensity values to a new, larger range
Eh - the range isn't larger - what you do is remap the intensities using a non linear transform (aka the "curves" tool in photoshop) such that you stretch out the low light values while compressing the highlight values together. The overall range of brightness values remains the same.
In otherwords you are increasing tha dymanic range of the lowlights at the expense of the highlights.
Its the fine art of processing vastly under exposed images to make them look properly exposed! And note to properly expose the image would literally take weeks if you had weeks of continous darkness! (fancy a polar winter trip!)
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Televue 85, GM-8/Gemini, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB)
Coronado SM60/BF10, Baader Herschel Wedge
Leeds Sky Clock Ripon Sky Clock
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jmX
super member
Reged: 04/23/09
Posts: 170
Loc: Orange County, CA
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Quote:
Eh - the range isn't larger - what you do is remap the intensities using a non linear transform (aka the "curves" tool in photoshop) such that you stretch out the low light values while compressing the highlight values together. The overall range of brightness values remains the same.
When I stretch, I usually stretch a small section of the images, maybe the middle 1/3, the most, and it may start out as 1/3 of the range (say, 21000...42000 in 16bit range) and it ends up 22000...46000. That range of values was in fact, mapped (nonlinearly) to a larger range. 90% of the "stretches" I do end up doing this as I described.
I work with pixels and different bitdepths every day, so maybe the way I describe it isnt the way others would describe it, but its the way that explains it best to me. 
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Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
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bryansay
super member
Reged: 02/25/09
Posts: 111
Loc: Georgetown, TX
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Hi all, thanks for the great feedback. I will try to answer some of the questions (and ask a few more) here in subsequent posts. It has become obvious to me that processing is a weak spot for me and I appreciate all of the help that I can get from the group. As of June this year I had never opened photoshop or tried to even adjust the color of an image so my learning curve has been pretty steep.
To get started, I will first describe my basic workflow in the hopes that the more experienced folks can point out ways to improve.
For this image I did the following:
1. Stacked the image using Images Plus 3.1
Lights, Master dark, Master Bias, flats, dark flats
Min Max Excluded average with automatic dark matching
2. White balanced the image in Images Plus by opening a reference image of a 16% gray card and White Paper under noon sun.
Open "Color Balance", select white balance, click on 16% Gray in image; Leaving the dialogue open, switch to astro image & apply color balance settings
3. Perform the initial "stretch" using the "Digital Development" Tool in Images Plus
Move the "breakpoint" slider to about 10,000 and then adjust from there.
Question: Can one of you explain to me what "digital development" in IP is actually doing in photoshop terms? I suspect that this is a rather sophisticated form of "curves" adjustment.
4. Save the file as a TIF and Open in Photoshop
Use Image; Adjustments; Threshold to evaluate the darkest and lightest areas of the frame (do not apply)
Set measurement points in darkest, lightest and areas of nebulosity in the image using Color Sampler Tool
6. If Gradiant is present: Duplicate Image; Darken one layer till gradient measurements are roughly equivalent to the other. Create a hide all layer mask and adjust with the gradient tool to reveal the darkened area to balance the gradient.
7. Use the levels command to lighten the image in RGB; Watch the measurement points to leave the darkest point at approximately 30.30.30 and the lightest point less than 255.255.255 Adjust the midpoint to taste
I now have an image which is relatively bright in the core (individual stars visible) but with little nebulosity showing I am now ready for "crude" blending
8. Duplicate the image creating a new layer; in the upper layer, Peform a Curves adjustment to lighten the midpoints so that the core is blown and the surounding area of nebulosity looks good. Use the Erasor tool with a large soft brush (300 pixels) to erase the core revealing the original core from the layer below.
9. Duplicate the upper layer: Repeat Curves adjustment and Erasor to lighten nebulosity without increasing the core. (continue progressively until satisfied with image)
10. Flatten image,
11. Filter; Noise; Reduce Noise
12. Sharpen with Filter; Sharpen; Unsharp mask
13. Resize the image, crop etc to taste.
14. Add Star Difraction spikes using Noel Carboni's Astronomy Tools.
(sorry guys these are not natural, but used judiciously, they really enhance astro images. I post most of my images on facebook for my family and non-astronomer friends. My wife in particular likes them....)
15. Add Astro Frame using Noel Carboni's Tools
16. Save as JPG and post for all my friends on Cloudy Nights.
17. Chew fingernails waiting for feedback;-)
There you go. I am a very imature processor and would like to hear suggestions on how to do this better. I have read three books on photoshop and done a number of tutorials over the past few months. The single best resource for me has been Jerry Lodriguss' book "A Guide to Astrophotography with DSLR Cameras". This includes a section on processing with video tutorials. I have not mastered many of these techniques, but I am getting better. For example, Jerry has a very sophisticated method for generating the layer masks from the image itself. I still struggle to make it look as good as his.
Go easy on me guys, I am still very much a newbie.
Initiate finger nail chewing sequence....
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Bryan Sayler
Celestron C9.25; Orion ED80
HEQ-5; Orion ST-80 w/starshoot
Nikon D80; Canon 40D Hap Griffin Mod
Empty Wallet
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bryansay
super member
Reged: 02/25/09
Posts: 111
Loc: Georgetown, TX
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Quote:
I like it, except I think the m42 core looks strange... I actually prefer it slightly blown out, because it looks *right*.
I understand your perspective, but I think that this is a taste thing. I prefer not to have any part of the image "blown". Since we are stretching the image to reveal color that none of us could see otherwise, I am comfortable with doing this in a non-uniform way so that the detail is visible in all parts of the image at once.
Quote:
Also I think you could stretch the bottom end of your 2 minute exposure data to get the rest of the dusty parts of the nebula on the outskirts of M42
I am coming to terms with the amount of processing to do. My earlier efforts have all been overdone and did not look natural at all. Learning photoshop has been a fascinating process for me and I suppose that it is natural for newbie's to "overprocess" at first. Perhaps my pendulum has swung too far the other way.
Thanks for the comments. I do appreciate your insight.
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Bryan Sayler
Celestron C9.25; Orion ED80
HEQ-5; Orion ST-80 w/starshoot
Nikon D80; Canon 40D Hap Griffin Mod
Empty Wallet
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Javier1978
sage
Reged: 02/12/09
Posts: 228
Loc: Buenos Aires, Argentina
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Beatiful image of Orion and the running man!
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6" f5 Sky Watcher Reflector
Eq3 mount (Dual Axis)
Unmodded Canon 300 D
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