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M16 with the Pillars of Creation

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#1 jhayes_tucson

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Posted 05 August 2014 - 11:37 PM

Just before I headed to the big air show in Wisconsin last month, I was able to spend just about 2 hours on M16.  From Oregon, this object is pretty low so this shot is through a lot of airmass.  I had some troubles with wind and a focus shift so I had to spend two nights before I had 39 useable subs (yeah, I lost one.)  I really need to get my OAG working to tighten up the guiding.  It isn't terrible, but now that I have a better mount, I think that I can easily take it up a notch.  I finally got around to processing the data and I'm pretty happy with how it turned out.

 

Here's the poop:  Taken with C14 on a AP1600 with a Hutech modified 6D at the F/11 focus.  The subs were 181 seconds each at ISO 1600.  Guiding was with a Vixen 95 mm modified Mak + NexGuide auto-guider.  I didn't take any flats or darks.  (Everything is super clean and at the F/11 focus of my C14, the flat field is actually fairly uniform out to the extreme corners.)  This is about a 2/3 crop of the full frame data.  The data was stacked and partially processed with PI and final processing was with PS CC.  My intent was to present it in "natural colors" (i.e. mostly red) but the pseudo-Hubble palette that I came up with just looked way better. I'm probably just conditioned to expect this object to look this way.  C&C always welcome...

 

John

 

 

PS.  I downsized this image to fit the old CN size limit.  You can find the full resolution image at:http://www.astrobin.com/111750/

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#2 telfish

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Posted 06 August 2014 - 06:40 AM

Amazing! The 6d sure is a special DSLR!



#3 coinboy1

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Posted 06 August 2014 - 08:16 AM

Beautiful, is that an edge 14?



#4 Campos

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Posted 06 August 2014 - 08:24 AM

Spectacular result John!

Imaging at > 4000mm takes some serious skills :)

 

Congrats!



#5 jhayes_tucson

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Posted 06 August 2014 - 09:23 AM

Thanks guys!  This was taken with a non-Edge C14.  The HD is definitely better but the C14 works surprising well.  You've really got to have good seeing, use a big sensor, and get everything just right before you clearly see the difference.

 

To paraphrase Fort Minor:

This is ten percent luck, twenty percent skill

Fifteen percent concentrated power of will
Five percent pleasure, fifty percent pain
And a hundred percent reason to control all that gain!
:lol:
 
Of course, a little OCD always helps too...
John


#6 ManicSponge

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Posted 06 August 2014 - 09:31 AM

Very nice, John. I like the colors as well. It's amazing to me, that images like this can be taken from our backyards. (Albeit, not easily!). Love the detail in the pillars, with traces of wispy gas at the tips. I'll stick to my short focal lengths for awhile, I've got my hands full with that! Glad somebody has the patience to get "up close" though.

Regards, Kyle



#7 JoeR

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Posted 06 August 2014 - 10:16 AM

Very nice detail at that focal length. How did you process the Hubble Palette using an OSC camera without narrowband filters?



#8 srosenfraz

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Posted 06 August 2014 - 12:28 PM

Very well done, John - I don't recall ever seeing an RGB image presented in Hubble palette.  Quite imaginative!



#9 Tassydevil

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Posted 06 August 2014 - 03:30 PM

Very nice John :waytogo:



#10 jhayes_tucson

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Posted 06 August 2014 - 06:45 PM

Very nice detail at that focal length. How did you process the Hubble Palette using an OSC camera without narrowband filters?

 

Well, I did it with a lot of screwing around in PS!  First, I stacked, cropped and stretched the image in PI. Then I imported a 32 bit tif into PS where I continued to tweak the stretch.  Then I used the "Image/Adjust/Import Color" option to import the built-in abstract Blue/Gold palette.  That doesn't quite produce the result anyone would want so there was a fair amount of color tweaking using both levels and curves.  I tried to keep it linear but at some point, I had to modify the R, G, and B curves to make some minor non-liear adjustments in order to balance the background relative to the middle zone.  I kept everything in 32-bit floating point mode until the very end when I did a few minor tweaks only available with 16-bit images.  I can probably reproduce it but the weakness of my approach is that it's hard to reduce it to a simple step by step recipe.  Mostly, I just eyeballed the result while I fiddled with the colors until I was happy with it.  The one thing that requires some care is that these kinds of color tweaks can really bloat the star images if you aren't careful so I took great care to minimize any effect on the star images (with moderate success.)  Anyway, that's why I referred to the colors as a pseudo-Hubble palette.  It's not the real thing but it still looks pretty good.

John



#11 mmalik

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Posted 06 August 2014 - 07:52 PM

Looks very good John. Minor star bloating I see; what kind of filtering did you use besides 'T' mod? Regards



#12 jhayes_tucson

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Posted 06 August 2014 - 09:38 PM

Looks very good John. Minor star bloating I see; what kind of filtering did you use besides 'T' mod? Regards

 

Mike,

You are right.  I pushed sharpening right to the edge to emphasize detail in the pillars.  I often create a layer mask to accomplish this, but this time, I chose to try to avoid mask "painting" and to operate globally on the data.  I felt that the minor bloating was worth the improvement in detail.  I used the "Smart Sharpening" option in PS that allows noise control.  Flattening the stars (i.e. bloating) vs detail enhancement is always a struggle.  Like most, I prefer the more natural Gaussian-like intensity distribution of star images that comes straight out of the subs.  One of these days I'll work on separating the stars from the nebula to see if I can treat each component a bit differently.  Maybe someday I'll get this whole thing figured out...

 

As for filters, I didn't use any optical filters at all.  This is from the straight from the camera. (Hutech 6D).

 

John

 

 

PS  I looked at some of my earlier versions and realized that a fair bit of star "flat-topping" is happening when I stretch the image--well before I do any sharpening.  So I'll look into how to control that a bit better too. How do you handle that issue?


Edited by jhayes_tucson, 07 August 2014 - 10:39 AM.


#13 thgr8houdini

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Posted 07 August 2014 - 01:51 PM

Beautiful shot!



#14 KapHn8d

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Posted 07 August 2014 - 02:44 PM

This is awesome. Congrats on a great image!

 

/c



#15 WesC

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Posted 08 August 2014 - 06:22 PM

Really very nicely done, John!



#16 jhayes_tucson

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Posted 08 August 2014 - 11:17 PM

Thanks again guys!  There are so many folks doing such incredible work around here that I'm still just trying to catch up so I appreciate the encouragement.

John



#17 Robert York

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Posted 08 August 2014 - 11:45 PM

Thanks for posting this! Mainly because it's encouraging me to quit stressing over trying to get flats, darks, etc.

 

Did you use any bias data for this? Did you use dithering on the shots?

 

Using my 6D, I try to do everything just right and I ended up with a pretty **** result. When I just aligned and stacked, it came out way better. Granted, I did dither the images, so that helps with pattern noise. I'm trying to get a better feel for how much of this processing is really necessary. Is dithering enough? Dithering and Bias? Do you even need either of those?

 

Thanks again!



#18 jhayes_tucson

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Posted 09 August 2014 - 12:42 AM

Robert,

I didn't use flats, darks, or bias data.  I've got the camera pushed very close the rear plate on the scope to minimize vingetting.  I've taken flat data with the 6D and frankly over everything but the extreme corners, it's fairly uniform.  I'm not saying that flat data won't improve the image (it will); but, in my case, it's not a major issue.  This data was taken on an evening with an OAT of about 65 degrees so it wasn't cold, yet the 6D performed quite well with respect to noise.  Even when I do a really hard stretch on the subs, I don't see a lot of fixed pattern noise so darks won't do much either.

 

Now, when it comes to dithering, there's a story.  First, I took this data over two night--mainly because I can only get about 1-1.5 hours on this object while it's high enough above the southern horizon.  I wasn't successful at lining things up perfectly between the two night (close but not perfect) so that dithered the two sets of data.  Second, I am battling a strange phenomenon that I haven't quite figured out.  If I look at each of my 3-minute subs, the stars are pretty close to pinpoint round and yet if I rapidly scroll through my whole set of subs, the image walks across the sensor.  I only pause for about 2 seconds between the subs so I am completely baffled as to why I can have sharp star images and still have image walk.  It is exactly what you want for dithering…but I'm not doing it!  Whoa.  I've measured the walk and computed how out of round the stars should appear and (at least on the one data set I measured) it doesn't jive.  The stars should be slightly oblong.  I'm still scratching my head over what in the world could be causing the scope, the sensor, the optics, or anything else to shift a little between each two second frame.  I'll have to go back and look at the camera for this data set to see how much the set moved but I bet it did.  I've been pondering making a post about this but I really don't have my ducks in enough of a row with data and such to have a controlled discussion about this one yet. But, since you asked, yes…I am dithering; but not exactly intentionally.  This may be something as simple as "mirror flop" or flexure but it's hard to isolate.  This is another reason that an OAG would almost certainly help.  I'll post the solution, the problem, or both if I ever make any more progress on it.  In the meantime, I'm happy enough if I can keep getting results like this one.

 

As for processing, yes there was a fair amount on this image; mainly because of the color palette.

 

My advice is too keep it as simple as possible when you start and to work your way up as you get things working.  Just start with lights and get your processing figured out first.  You should be able to get some very nice results.  Flats, darks, etc can then be added to make things better and to fix specific problems.  AP is definitely and exercise in divide and conquer as you work your way up.

 

John



#19 steven_usa

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Posted 11 August 2014 - 05:28 AM

Wow, no darks or flats!  Amazing, thanks for sharing that.     That we can take such images here on the surface, pretty neat.

 

I've noticed that in some of my own data: scrolling the images, I see star walk, yet I have no oblong stars (AVX mount, 450D, SCT).  However, I must use Darks, or I end up with diagonal streaks in the stacked image (at least using DSS; does PI do stacking also?)

 

So with a NexGuide, you aren't using PHD I presume? Just the built-in Celestron software, and it's talking directly to the AP1600?  Hmm, if you're going OAG, does your NexGuide need a new home? :)



#20 jhayes_tucson

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Posted 11 August 2014 - 10:10 AM

Hahaha…no my NexGuide doesn't need a new home but I do have a spare that I need to sell. :)   With my roll-out set up, I've been fighting using a PC and for most of my purposed the NexGuide works surprisingly well so I'm not quite ready to give up on it.  I may actually go to a ONAG and I think that the NexGuide may work with that.  The big problem with be the crummy binary image display for acquiring a guide star.  It talks to the AP 1600 just fine and in fact it should work with any scope with a "standard" guider input via a RJ45 connector.  The AP1600 does't need a lot of help so I turn everything (rates and aggressiveness) down pretty low.  As I've said, the Canon 6D has VERY low fixed pattern noise so darks haven't been necessary…at least so far.

John



#21 steven_usa

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Posted 12 August 2014 - 12:23 AM

That's fabulous equipment! 

 

The camera is not cooled?  (I suspect not, but just curious; here in Texas even in the evening, an uncooled DSLR can overheat and give up for the night)  Do you recall the temps of your RAW images as reported by the sensor?  

 

Any comments on your ISO1600 choice?  How dark do you consider your rollout setup?  Was it ISO1600 mostly because of the limited viewing time on M16? or local LP?  Or was that just what kept the histogram in a reasonable spot after 180sec?  



#22 fco_star

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Posted 12 August 2014 - 08:11 AM

Beautiful image!



#23 jhayes_tucson

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Posted 12 August 2014 - 09:36 AM

That's fabulous equipment! 

 

The camera is not cooled?  (I suspect not, but just curious; here in Texas even in the evening, an uncooled DSLR can overheat and give up for the night)  Do you recall the temps of your RAW images as reported by the sensor?  

 

Any comments on your ISO1600 choice?  How dark do you consider your rollout setup?  Was it ISO1600 mostly because of the limited viewing time on M16? or local LP?  Or was that just what kept the histogram in a reasonable spot after 180sec?  

 

Steve,

No, the camera is not cooled.  The air temperature on the night I took this was 65-70 degrees and I didn't check the sensor temperature.  The 6D runs pretty cool and the fixed pattern noise is VERY low.  I normally shoot at ISO 800 but I decided to experiment with 1600 for two reasons.  1)  A lot of folks are getting good results at ISO 1600, and 2) This object isn't above the horizon for very long at my location (maybe 1.5 hours) so I wanted to "amp-up" the signal a bit.  It came out pretty well so I might try it again the next time.  I operate the edge of a yellow/orange zone.  The Milky Way is very clearly visible, but I also operate on a taxiway at our local small airport where there are a LOT of lights.  The big problem with this shot was that as it got later, it approached the airport beacon, which is like have a 500W beam sweep over the telescope every one minute.  (It was the only place where I could position the scope for a good view of the southern sky.)  So, I pulled out a tripod and positioned a great big box between the telescope and the beacon so that the aperture was perfectly shadowed.  It looked totally crazy but it worked like a champ!   Fortunately, it was dead calm or a wisp of wind would have brought it all down.  I was able to get three minute subs and the histograms were right around 15-20%.  That's just a bit lower than I like but it worked fine.

 

Again…thanks for all the comments! 

John



#24 ignacio_db

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Posted 12 August 2014 - 05:19 PM

Very interesting choice of color palette, John. This is the first time I see such color treatment, mimicking Hubble with a osc camera. Given the short exposures at f/11, the camera behaved notably well noisewise. The details are very good, but I would expect more resolution from a 14-inch telescope. Maybe is the low elevation/seeing that makes it hard with such apertures.

 

Anyway, great job!

 

Ignacio 



#25 jhayes_tucson

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Posted 12 August 2014 - 06:41 PM

Thanks Ignacio.  I agree with you about the resolution and (trust me) I'm working on that.  The big problem with this object from here in Oregon, is the low altitude angle.  I shot this through an airmass of 2-4x.  Stay tuned…I'm working on taking the resolution up a notch.  If I can just get some clear weather next month, I might have some results.

John








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