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8SE Imaging (again)

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#26 Alex Post

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Posted 06 March 2010 - 04:18 PM

Before we can apply Levels, I do an incredibly simple trick that would keep trapezium region intact, while more subtle parts of the nebula will be affected. I use magic wand tool. I pick core region of the nebula while Tolernace level is set to 99. Then I "feather" the selection by 100 pixels. Finally I invert selection. We are ready to apply Levels and Curves.

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  • 3663928-step12_prepare_for_levels.jpg


#27 Alex Post

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Posted 06 March 2010 - 04:33 PM

After adjusting Levels and curves (numerous tutorials available), I go to the magic tools: Noel's Carboni for Photoshop. First step is to remove light pollution, which wokrs very well. The only warning here, it's easy to overdo.

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  • 3663948-step13_light_polution_removal.jpg


#28 Alex Post

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Posted 06 March 2010 - 04:36 PM

Next step is my favorite: again in Carboni's tools - Local Contrast Enhancement. I run it one or two times:

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  • 3663958-step14_local_contrastl.jpg


#29 Alex Post

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Posted 06 March 2010 - 04:40 PM

Final step is to resize and adjust color depth from 16 bits to 8 bits so that it can be posted on CN forum:

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  • 3663964-step15_resize_and_color_depth.jpg


#30 Alex Post

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Posted 06 March 2010 - 05:17 PM

And here is the final result based on 700+ images .

Obvious problem is vignetting. Which I am going to solve next.

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  • 3664053-v1_proc3.jpg


#31 Alex Post

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Posted 06 March 2010 - 06:23 PM

Comparison side by side: old method and new method:

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  • 3664143-m42_comparison.jpg


#32 tvader

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Posted 07 March 2010 - 12:54 AM

Excellent Tutorial.. Thank you very much - this should be a sticky!

#33 setldown

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Posted 07 March 2010 - 04:59 AM

Outstanding images with the 8se. Thanks for sharing your technique.
You have seemed to conquor the so called limits and challenges of the 8se. Well done, Alex! :waytogo:

#34 Skip

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Posted 07 March 2010 - 03:25 PM

Excellent Tutorial.. Thank you very much - this should be a sticky!


Hey Mods,

Can we get this done? I know this is mostly about imaging, but it IS about imaging with a NexStar 8SE (should also apply to the 6SE) and looks like it would be a good fit in this forum. After all, we always hear (and from many of us included) that the SE series is NOT good for imaging. Here is an excellent refutation of that "conventional wisdom" - at least for a bright object like M42. But I have to believe, with enough patience, it would work on many of the DSOs. Please make a sticky of this! I'm gonna need it as soon as I get my DSLR! :grin:

Cheers and clear skies,

#35 Peter9

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Posted 07 March 2010 - 04:22 PM

Excellent Tutorial.. Thank you very much - this should be a sticky!


Hey Mods,

Can we get this done? I know this is mostly about imaging, but it IS about imaging with a NexStar 8SE (should also apply to the 6SE) and looks like it would be a good fit in this forum. After all, we always hear (and from many of us included) that the SE series is NOT good for imaging. Here is an excellent refutation of that "conventional wisdom" - at least for a bright object like M42. But I have to believe, with enough patience, it would work on many of the DSOs. Please make a sticky of this! I'm gonna need it as soon as I get my DSLR! :grin:

Cheers and clear skies,


I'll go along with that. Invaluable information for any budding A.P inclined Nexstar owner.

Perhaps all the Stickies could be put into one thread entitled "Nexstar Stickies"

Peter.

#36 tvader

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Posted 07 March 2010 - 08:12 PM

Alex - What's your thoughts about using a wedge? while your results are very impressive. Do you think it would improve them?

#37 Alex Post

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Posted 08 March 2010 - 01:08 AM

Wedge would most likely improve AP results. However the reason I like 8SE is that it's light, compact, and it's very easy to transport and setup. Adding a wedge removes some of the attractiveness for a cheap basic scope.

I am planning to upgrade to a GEM, so I can't really justify getting a wedge. All additional parts that I bought for 8SE I can and will use for my future dedicated AP setup. A wedge would be unused I am afraid.

Now, if I had a wedge for some reason, would I try it? Of course!

Edit: this is my latest version, where I took ALL three nights' worth of data (1245 images), added 20 flats, and re-processed. It appears that a minor amount of contrast increase was achieved, especially visible at the bottom of the image.

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  • 3666887-v2_proc3_800.jpg


#38 Skip

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Posted 08 March 2010 - 09:30 AM

My goodness! That is simply stunning!!! :bigshock: :applause: :bow: :goodjob:

#39 TonyDralle

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Posted 08 March 2010 - 09:40 AM

Hi, Alex,

A few questions, if I may, about your very successful photography with your 8SE and digital camera (I have only a point-and-shoot digital camera, haven't ventured into DSLR's yet):

a) It appears that the hardware -- telescope and camera -- that you have makes capturing the multitude of images pretty straightforward, and that the real work goes into post-processing?

b) I don't understand how you instructed the camera to take hundreds of images without your intervention. Is that just a setting on the camera? (Here my ignorance about advanced digital cameras is becoming evident.)

c) Do most current DSLR's have the advanced features you used (Live-View, computer connectivity during image capture)? If not, what specific terms does one look for when reviewing a camera's capabilities?

d) What is the battery life of your computer?

e) Have you tried your lots of short exposures procedure on fainter targets?

Thank you for looking at my questions. Feel free to tell me that I can answer some of them myself by reviewing DSLR specs!

- Tony

#40 Alex Post

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Posted 08 March 2010 - 08:43 PM

Tony,

a) Mostly yes. Capturing is automated via a computer connected though USB to the camera. Once telescope is aligned I run 100-200 image sequence capture (assuming 10 sec exposure). I come back every 100 or so images to check that the scope has not drifted much. Some drifting DOES occur in my simplistic approach. Some people on this forum mastered alignment so well that objects can stay pretty much dead center for many hours. Not in my case. Processing is by far most time consuming step. It took my laptop 16 hours to crunch through 1200+ images. Good news was that it was doing it while I was mostly asleep. After images are stacked into a single composite by astro software (I use DSS, but several others are widely used. I use DSS because it's completely free and satisfies 90% of my needs), it takes just an hour or two to extract details using image processing software. I use mostly Photoshop, again because that's what I already had from my daytime photography. This is by far the most exciting part of the process. When details are finally starting to emerge.

b) I use EOS Utility from Canon. Once my camera is connected via USB to the computer I run this software. It has an option for "Remote Shooting". It also has a place where I can specify exposure, ISO and number of images to take. Once I am happy with the telescope pointing, I click "Start" and it takes specified number of shots.

c) A lot of DSLRs have LiveView, but not all. Canon is undisputed champion in astro world. Although all brands have their proponents. I'd say 3/4 of all people on this forum have Canons for AP. Live View was the single camera function that cut my prep time by hours. Pixels do not matter much. Latest Canon cameras have much better (lower) noise. I went for cheapest Canon camera with Live View.

d) Battery life of my computer is about 5 hours. But it was irrelevant for this latest experiment, since I had it setup right in front of my house. I ran the laptop from house power line. Note, that I did cheat by inserting a 2" light pollution filter in the optical path. Strictly speaking it's not a "cheapest, most basic" 8SE anymore.

e) No I have not tried that! I just did some estimates on Horsehead Nebula. It should frame quite nicely using same setup as I used for M42. I would use Alnitak as my reference star, by placing it right on the edge of the image. Can't wait till skies clear up.

#41 TonyDralle

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Posted 08 March 2010 - 10:08 PM

Alex,

Thank you Very much! I understand a lot better now how the camera and software function.

I helped test Tel's procedure for maintaining good tracking, but you're certainly doing OK if you tweak it only every 20 minutes or so.

Could you elaborate just a bit more on your statement "Live View was the single camera function that cut my prep time by hours." ? I can see its value in focusing and maintaining placement of the target stars, but isn't it "Remote Shooting" that enables you to walk away and let the camera/computer do all the capturing work? I'm still trying to understand this, so perhaps I'm missing something.

The Pleiades would make a good target. Maybe too late in the season for hundreds of photos per night.

Oh -- one more thing. Are the 1200 image files small enough so as not to tax your computer's memory?

Again, many thanks. You have me on the brink of wanting to try this myself (except I might be too old to make it very far up the learning curve!).

- Tony

#42 Chris Boar

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Posted 08 March 2010 - 10:21 PM

Great post.

Inspired me to try. I'm actually a pro-photographer and have a Nikon D3s and D3, but these are beasts, way to heavy to have hanging off the back of an 8SE.

I've also brought a Nikon D5000 for my 'walkabout' camera, what a great little DSLR. It's got live view, and I think it's the only DSLR that has a fold out swivel info screen. And pretty reasonable noise characteristics at ISO 3200. Cool! Mind you my D3s is quite usable for wedding photography upto ISO12800!

You've inspired me to try some astro-photography!

#43 Alex Post

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Posted 09 March 2010 - 09:26 AM

Could you elaborate just a bit more on your statement "Live View was the single camera function that cut my prep time by hours." ? I can see its value in focusing and maintaining placement of the target stars, but isn't it "Remote Shooting" that enables you to walk away and let the camera/computer do all the capturing work? I'm still trying to understand this, so perhaps I'm missing something.
- Tony

Tony, it may seem like a minor improvement, but it's huge in real time saving over just a few observation sessions.

In order to point telescope to the right location in the sky without a LV function, I had to use an EP first to align the scope and then to steer it to the target object. Then I would swap EP for a camera and then what?

Then I would need to start steering again, since EPs are not same weight as the camera and target that I was pointing at with EP no longer in view. Second problem was that now I was out of focus. Focusing with camera attached was a significant time waster. I would on occasion go full deflection of the knob back and force, which I swear is 1 million full revolutions of the knob. Once I was near focus, then I would attach a Bahtinov mask and start taking short (2-3 sec) images slightly adjusting focus. Before Bahtinov it was an order of magnitude worse. With LV function I do not even attach Bahtinov mask! I should, but in the pictures I posted above I skipped even that step. LV is good enough to get me near focus.

Finally, as computer-camera are going through hundreds of pictures, I can see what's going on on the LV and adjust scope pointing while session is in progress.

So LV is for
1) alignment
2) fine GoTo adjustments
3) focusing
4) adjustment through AP session

All without need to disconnect camera.

Regarding computer memory. Computer memory in the sense of volatile memory (RAM) is not affected, since only one picture remains in memory (even if that) at any given time. Once picture is recorded to a non-volatile storage device (hard drive) then next picture is taken. Hard drive storage needs to be significant, but nothing extravagant by today's standards. My camera (Canon XSi) records at 14MB per image. So 1000 images is roughly 14GB of hard drive space. My laptop that I use for image recording has 320GB drive, which is good for 20 or so imaging sessions. Taking 1000 images is not something that you would do every night. 10 seconds per image, plus 2 seconds per image transfer from camera to computer, 12sec x 1000 images = 12,000 seconds, or 200 minutes, or 3.5 hours. Realistically, close to 5 hours for a session.

#44 Alex Post

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Posted 09 March 2010 - 09:28 AM

You've inspired me to try some astro-photography!

Thank you. I would like to try Horsehead nebula, 200-300 images at 10 sec. If your sky conditions allow that, I would be interested to look at your data. What software do you use to stack your astro pictures?

#45 Skip

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Posted 09 March 2010 - 11:41 AM

Alex,

If I could jump in here with a question, please: I have the freeware, Registax 5. I know it works for planetary and lunar work, but is it OK for DSOs? Or do I need DSS for that? Like Tony, I'm on the brink of giving AP a try. The learning curve scares an old guy like me, but nothing ventured, nothing gained. So, for now, all I'll need is a decent laptop and a DSLR camera - the Canon XSi is the one I've been lusting after.

Thanks,

#46 TonyDralle

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Posted 09 March 2010 - 12:22 PM

So, for now, all I'll need is a decent laptop and a DSLR camera


Skip,

If you and I could agree on these items, maybe we could get discounts by ordering two of each!

- Tony

#47 Chris Boar

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Posted 09 March 2010 - 01:15 PM

What software do you use to stack your astro pictures?


I don't yet, I've never done any! Although I am equipped with PS CS2 so I imagine I will be able to get plugin for that?

Lots of reading to do!

#48 Alex Post

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Posted 09 March 2010 - 01:53 PM

Skip,

Registax does not work with DSOs. I use Registax for lunar and planetary imaging exclusively. DSS is for DSOs and does not work for planetary.

It is very easy to start AP-ing with 8SE and a DSLR with LV. SO easy in fact, it should probably be one of the first things new 8SE owners try. It may not be easy to see E and F starts visually in M42 trapezium, or observe craterlets in Plato crater on the Moon, but it surely much easier to make breathtaking M42 picture with 8SE. All you need is a camera attached to the scope and Canon EOS Utility that comes on a CD with your camera to collect data.

For processing, even if all you do is to throw collected 100 files on the very first screen in DSS and click Select All, Process - you will end up with images that will change your life :) (do not forget to export files from DSS and open in imaging software and apply levels)

#49 TonyDralle

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Posted 09 March 2010 - 02:08 PM

Registax does not work with DSOs. I use Registax for lunar and planetary imaging exclusively. DSS is for DSOs and does not work for planetary.


Alex,

What is it about the stacking programs that makes them suitable/unsuitable for DSO's/planetary?

BTW, thanks for your reply about the merits of LiveView.

- Tony

#50 a_savvin

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Posted 09 March 2010 - 02:10 PM

Hi Alex
Great post. I learn a lot from you topic.
I have noticed you mention about object
alignment after you located object with eyepiece
it's not the same position once you connected camera.
I got the same issue and I am thinking to get
Celestron radial guider. I thought in this case
I will be able to have camera connected to the
telescope and I will be able to align object /sync
the same time using eyepiece connected.
Do you think it might help?


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