Aug 27, 2013

PixInsight: Creating a Luminance Mask

A view from above Kofa
Photo by Chris Hanrahan
I had big plans to do some real writing this weekend, but we had four days of rain in Arizona.  For me, this meant a trip out to the desert to play in the rain.  With temperatures 40 degrees (Fahrenheit) below normal the day was spent hiking in the Kofa National Wildlife Refuge - my favorite place on Earth.  

As a result, not much actual writing got done.  And when I say "not much", I mean no writing got done.  Instead, for the uninitiated, here's a step by step process on creating a luminance mask in PixInsight.  As you'll see - it's really easy.  And in PixInsight, this is a technique you'll use in various ways over and over and over.  Enjoy!!

Creating a Luminance Mask

Aug 7, 2013

PixInsight Deconvolution

 After commenting recently on a thread in the AZ-Observing mailing list about PixInsight it sparked multiple side conversations with other list members asking some questions about deconvolution in PixInsight.  This animation does pretty much sum up the experiences of many including myself when it comes to getting good results.  After much trial and error and gnashing of teeth I have reached a point where I can get some decent results.  The conversations from the mailing list encouraged me to go ahead and put together a video and post on deconvolution in PixInsight.  I'm not saying it's the best way, but it does work and I've enjoyed some good results with it.

World class imager Manuel Jimenez put together a tutorial some time ago that taught me much about PixInsight's implementation of deconvolution.  His tutorial can be found at his website. There are a few points to remember in order to get the best results.

1 - Do deconvolution on a linear image.  Before you stretch.
2 - There's only so much deconvolution can do.  It can't rescue a bad image, but it can make a decent one really "pop".
3 - Use the Dynamic PSF process module.  It's your friend.
4 - Create a star mask for local deringing support in your image.
5 - Create a luminance mask to limit the process to high signal areas.

The Final Result

Like the image in the video I also did deconvolution on the OIII and SII data that I had collected in my attempt to recreate the Pillars of Creation image.  Shown below is the end result.  This was shot with my Explore Scientific ED152 f/8 Apo triplet from southern Arizona.  It's a total of 37 hours of exposure time and processed entirely in PixInsight.  Thanks for watching.  Please contact me if you have any questions, comments or improvements to my process.

Here's a link to a larger version of this image:
M16 - Eagle Nebula in Hubble Palette
37 hours of exposure

Jun 19, 2013

Grand Canyon Star Party

Each June for 23 years now the National Park Service has hosted the Grand Canyon Star Party.  It's always around new moon and always in June.  If you're planning a trip to the Grand Canyon (and you should!) and you're astronomically minded this is the best of both worlds.  If you're curious about future dates as you plan that vacation they can be found here.  If you want the quick answer - the 2014 edition will be held from June 21 to June 28.  This is from last quarter right up to new moon so the skies will be inky dark every night.   The star party is made possible by volunteers.  Generally speaking, the festivities at the South Rim are coordinated by the Tucson Amateur Astronomy Association and the indefatigable Jim O'Connor.  The North Rim edition is coordinated by Steve Dodder and the Saguaro Astronomy Club based in Phoenix, Arizona.  

Which Rim Is Best?

That really depends on what you're hoping to find.  The star party at the south rim is much, much larger and features many more astronomers.  it's bigger in every way than the star party at the north rim.  It's also much easier to get to for most people than the north rim.  it's just a short drive off of Interstate 40 to get to the south rim.  You can even take a train right to the rim from Williams.  Crowds are much larger and lines for the telescopes can be long.  It is probably the ideal place for many would be attendees.  Personally, it is not for me.  But that's not because of the star party - it's just the south rim in general is not my typical flavor.  I'm very much into the outdoors and enjoying the natural beauty of my state and the amount of development necessary to accomodate 5 million visitors per year.  Bus stops and shuttles are not my idea of natural scenic beauty.  The canyon is still beautiful but the atmosphere isn't really my cup of tea.  Still, if the canyon is a stopping point on a larger vacation - the south rim is a great place to attend the star party.  

A panoramic view from Widforss Point, about a 5 mile hike inside the Grand Canyon National Park
on the North Rim.

The north rim is an entirely different world and one well suited to everything I love about amateur astronomy and being outdoors.  Less than 10% of the park's visitors go to the north rim so crowds are much smaller. It tends to be a destination where people stay for a few days rather than a stopover point.  It takes about 3 hours longer to get there than the south rim from my home near Phoenix, but it's worth every extra minute.  The star party is much smaller featuring about a dozen telescopes.  Those telescopes though are setup on the veranda of the North Rim Lodge and feature devastatingly beautiful views of the canyon.  Both years that I have volunteered at this star party my telescope has been less than 30 meters from the rim of the canyon.  Check out the time lapses from this year's star party.  Both were shot from the north rim and show what you can expect from this star party.  I hope to be there again next year showing the night sky to anyone who will stand at the eyepiece.

Mar 19, 2013

Messier and the ED152

After driving through a punishing thunderstorm
to get to the campsite, I was greeted with a
fantastic rainbow to start my first night out.
It was the best of was the worst of times.  So said Dickens to open A Tale of Two Cities.  Clearly, Dickens wasn't an amateur astronomer and clearly he did not tag along with me on my latest jaunt to the desert.  Had he done so it might have gone something like "It was a freakin' awesome time!". 

In my less fun, but better paying actual job I've been flat killing it as of late.  I've had more work than I know what to do with.  This is always a blessing when you're self employed.  It's been good through most of this long, grinding recession and I've been careful not to complain (much) about such a first world problem as too many people trying to give me business.  Eventually it does take its toll and I was ready for a vacation.  Early in the year I scheduled a nine day outing to the desert culminating in the Saguaro Astronomy Club's annual Messier Marathon.  I look forward to this event every year.  I also look forward to the East Valley Astronomy Club's All Arizona Star Party held at the same site in autumn each year.  If you're reading this and you're dense, that was your hint to clear your calendar and make plans for the event.  It doesn't appear that they've announced the date yet - but it's a pretty good bet that you'll want to plan for November 1st and 2nd.  Just sayin'.

Doing Time

Over the nine days of the trip I had a couple of goals astronomy-wise.  I wanted to put my new Explore Scientific ED152CF through its paces.  It's a 6" f/8 apochromatic triplet and is designed to be the big brother of the popular ED127 refractor.  I've professed my love more than once for the ED127 and I've been quietly sitting on the new telescope since early January waiting for a chance to put it to use.  Other than a few hours of hastily stacked hydrogen alpha data I had not been able to use the telescope.  I'm happy to report that I was able to collect a huge amount of data over the nine nights that I was in the desert - about 60 hours worth of it.  Stay tuned for the first color image from the scope over the next few days. 

My second goal was to try my hand at some time lapse photography.  I had always been interested in trying my hand at it.  With a few pointers from friend and fellow amateur Tom Polakis, I made the decision to use some of my time to give it a go.  Below is the first of the time lapses that I shot and completed during the week.  This was setup and shot as soon as the weather cleared for the first time - about midnight on Saturday, March 9th.  It's not perfect, and you can see if you watch closely that dew was an issue at some points.  But it was my first and I was really satisfied with the outcome.


Get To The Telescope Already!!

What is there to say?  It's gorgeous and looks like it belongs on the AP900.  The OTA alone weighs a mere 24 pounds which I found impressive for such a large telescope.  I don't know if I would want to deal with a larger refractor than this if I was taking it to the field.  Emphasis on "I don't know".  If somebody wants to give me a larger refractor so that I can test that thought I would be more than willing.  But I digress....
At some point, there will be a full review of the scope coming.  Once I feel like I've developed a good understanding of its performance and its nuances, but I do have some first impressions to share.  A common question already has been from people wondering how it compares to the ED127.  In short, take the ED127 carbon fiber and scale it up to a much larger OTA.  Even though it's only an inch of aperture, the physical size of the scope is much larger.  If you haven't seen my review of the ED127 it's a good place to start.  It has many similarities.  It has the same flip around dew shield.  Some people don't like it but I'm a fan of it.  The scope is also delivered in a similar, but much larger transport case.  The total package when UPS dropped it off at my door was 90 pounds.  Fortunately, the folks at Explore Scientific considered that and the case is wheeled at one end making it much easier to transport. 
One of my complaints about the ED127 was the focuser.  I did not love it.  This has definitely been remedied on the ED152.  It comes standard with a 3" Feathertouch focuser from Starlight Instruments.  It is most certainly up to the task of carrying your heaviest eyepiece and I have no doubt it can handle any imaging load that I'm capable of affording and attaching to it.  Another complaint of mine was the threaded dust cap being too close to the glass.  The dust cap on the ED152 is not threaded and fits snugly on the OTA.  I have little concern about hitting the glass with this dust cap.  A great improvement for the visual observer is the finderscope.  The ED152 comes with the same illuminated reticle and correct image finder that you've seen on the other Explore Scientific scopes.  The kicker is that it's also a right angle finder - much easier to deal with when you're finding objects that are high in the sky.  Finally, the finderscope mount has an ingenious feature.  The mounting itself that holds the rings is drilled out from front to back with a small sight hole.  I imagine that this sight hole will make that initial alignment of the finderscope and telescope a simple operation as you can use the sight hole to get a rough alignment.
I'll have a better formulated opinion of the optical performance once I process some of the data that I collected but my first impression is very positive.  The quality of the data appears to be on par with that of my ED127 so I'll extrapolate to say that the ED152 is fulfilling it's role as the big brother admirably.  I'll comment again once I've completed an image or two. 
I can hear it now..."What don't you like about it Mike?" As I said, a full review is coming but there is one minor quibble - the stock dovetail.  It's short.  Being only about 6" long I didn't feel comfortable with it in the saddle of my AP900.  I didn't have any issues with it, but I was never comfortable either.  I intended from the start to replace it with a much heavier duty dovetail and I did eventually do that. 
My second time lapse of the week was indeed the telescope itself.  On March 11th, I started the observing run from CCDAutoPilot about 30 minutes before sunset and walked away.  The time lapse is an entire night of imaging without human intervention at any point.  The telescope collected data on 3 objects over 9 hours while focusing every 60 minutes.  The telescope collected dawn flats and parked itself at the conclusion.  The video ends just as flats are being collected.

The Marathon

The observing trip finished with the Messier Marathon.  I got to see and talk with people I don't get to see often enough.  Moonlight was a factor as the moon was nearly first quarter but it didn't stop us from having a good time.  Kevin from Woodland Hills Camera and Telescope made the drive out from Los Angeles and spent a couple of days with us.  Kevin brought some goodies with him - the new 25mm ES100 eyepiece.  We tested it thoroughly and side by side with the gold standard of wide field eyepieces - the TeleVue 31mm Nagler.  The general answer was a little different depending on who you asked.  Some liked the ES100 better than the Nagler (including myself) and some liked the venerable TeleVue.  Everyone who did the side by side comparison did agree that the ES100 was a worthy adversary.  I liked the darker background of the higher power eyepiece and thought that colors looked more saturated through it.  Most people agreed with me on this assessment.  I thought that the edge correction was similar on both eyepieces but many didn't agree with me there giving the edge to the Nagler.  I've been very impressed with the ES100 eyepieces that I've been fortunate to use and I did end up ordering one of the 25mm for myself. 

Kevin from Woodland Hills Camera & Telescope
spent the early evening capturing some
great shots of comet PanSTARRS.
My wife ended up attempting the marathon and got 65 out of the first 67 before she ran out of objects and went to bed.  She awoke at 4am but couldn't work up the effort to get out of the toasty warm bed and go outside to finish the marathon - a decision she said she now regrets.  I continued to work the sky shooting H-Alpha data early and LRGB data late in the night.  While the laptop was busy doing that, I spent the evening with my 15" Obsession attempting to become a better visual observer.  One of my successes with the imaging game has been that I've reached a point where the rig runs itself once it's all setup.  This has afforded me the luxury of getting back to some visual observing which was my first love affair with the sky.
It was a great trip overall and provided some much needed adventure, astronomy and relaxation.  I returned to work ready to get after it all over again.  Every trip to the desert leaves me feeling better about everything there is in life by the time that it's over with.  Check back soon for images and processing notes from the data that was collected during my outing. 

Feb 27, 2013

A Crash Course On PixInsight

Have You Lost Your Mind?

If you've mentioned to any of your astro-imaging colleagues that you're interested in PixInsight that was probably the nicest response that you received. For a long time in the astrophoto game, a combination of some pre-processing software (Astro-Art, MaximDL, CCDSoft, Nebulosity) and PhotoShop were the only game in town when it came to producing nice astrophotos.  Though it's been around for significantly longer than that, the PixInsight platform has started to make some buzz in the last couple of years and has gained a lot of die hard converts - myself included.  With it's increasingly common use and mention on The Internets, PixInsight is becoming a regular topic of conversation among new and experienced astro-imagers.  It seems to me that there's some amount of uninformed opinion and outright disinformation whenever PixInsight is the topic.  Message boards are littered with a standard litany of responses whenever the topic is brought up:
  • "It's too hard."
  • "There's no documentation."
  • "You have to be a programmer to use it."
  • "It doesn't have layers so it can't be used to process an astrophoto."
  • "It's impossible to learn.  I can't find any help online."
These statements are all patently false.  The only one that is partially true is the claim of no documentation.  There is some documentation within the application.  The processes that are documented are an absolute encyclopedia of the process being covered.  However, not all processes are documented and therein lies my one complaint.  Like others, I wish they'd finish the documentation.  The rest of it though - false.  So in this installment I'm going to save you the trouble of using The Google to figure out how to use PixInsight.

How I learned PixInsight

It's stupidly easy how I learned to use PixInsight.  First, I downloaded it and installed it after getting a license for a 45 day trial.  I took one of my own images, and I went to Harry's Astro Shed and I simply went through all of the newbie videos one at a time until I had completed an image.  It was that simple.  I'd pause the video and apply it to my own image and then continue moving forward.  Over the course of a couple of hours I got introduced to all the major processes and the "correct" order that they should be used.  Here's the first image that I completed with PixInsight entirely by just walking through Harry's videos with him one time.
My first PixInsight image.  It's not my best work ever, but going through the process showed me immediately that this is a software package with awesome power and potential.  This was shot with a QHY8PRO one shot color CCD and a 127mm refractor.
If you'd like the same result, just do what I did.  Here's some pointers to make the learning curve a little easier.
  • The first rule of PixInsight is "It's not Photoshop"
  • The second rule of PixInsight is "IT IS NOT PHOTOSHOP!"
  • Watch each video.  The entire video.  Pause it.  Play with the controls in PI yourself.  Restart it.  Repeat.
  • Expect that you're going to have to stop and truly learn something.  It's true that if you just start it and click the mouse at random points on the screen expecting APOD worthy results you will be disappointed with the outcome.
After that, I started to look for additional resources.  There are plenty.  I studied them and tried to learn from them.  When I had a question, I asked on the PI forums which are frequented by pretty much the entire development team.  Juan Conejero's responses in a lot of the messages have a tendency to turn into mini-tutorials and lessons in image processing theory.  Which is to say - They're awesome!!

Other General Resources

Harry's Astro Shed: It should go without saying to have a look at Harry's Advanced Videos.  They dig deeper into some of the other processes that'll really help you dress up your images. 
Rogelio Bernal Andreo's Orion mosaic is one of
my favorite PixInsight processed images.  Check
out his other stuff at
Warren Keller's IP4AP:  Warren recently produced a series of tutorials on PixInsight with the assistance of PixInsight user Rogelio Bernal Andreo.  There are some free ones there too so that you can get a feel for them.  I haven't seen them myself, but I have been through Warren's series on Photoshop and I can tell you he puts together an excellent, useable set of tutorials to help you get started.  A second set of more advanced tutorials is in the works as I write this. Crazy, right?  The PixInsight website has tutorials?  You're kidding me.  They are there including those for older versions that are still useful to help you get the chi of the PI platform.  Go to and look under Resources on the right side of the page.

PixInsight Documentation:  Yes, much of it isn't there, but the documentation that is there is mindblowingly good.  Read the documentation on image registration and you will learn more than you ever wanted to know about how the software actually goes about matching up the stars to stack a set of images.    

In the Months to Come...

It's my goal to start bringing a little PI help to these pages too by covering some bite sized pieces of it as I unveil new images.  I'm in the process of locating my imaging rig at a remote site that should allow me to do a lot more imaging than I've been able in the last few months.  So I'm hoping that 2013 brings a lot more imaging time and lot more of me trying to give a little something back to this incredible hobby.

It was this image by Manuel Jimenez that made me take a serious look at the PixInsight
platform.  See his other amazing work at  He also a nice tutorial on
deconvolution in PixInsight.

Jan 29, 2013


January 2013 - B33 in Hydrogen Alpha (6.5 hours)
My first deep sky imaging session through a telescope took place two years ago today.  I'd already taken a handful of wide field and piggyback astrophotos with my Canon 60D DSLR.  I realized that I was far too warm and comfortable taking these astrophotos in my backyard and that I needed to get very far out into the desert if I wanted to properly freeze my southern hemisphere off. So that's exactly what I did.  I packed up my gear and headed west to the Saguaro Astronomy Club's dark sky site on BLM land 90 miles west of Phoenix. 

I setup my CGEM and secured the 1100HD optical tube in the dovetail.  I removed the secondary and threaded the Hyperstar into place and finally I attached the Canon to the end of the Hyperstar.  Good to go.  Once it got dark enough I aligned/calibrated the CGEM and then used Celestron's awesome All Star Polar Alignment routine.  The polar alignment was more than accurate enough for the two minute subexposures I had planned (I hoped).  Using a homemade bahtinov mask I focused the telescope and slewed to the famous Horsehead nebula afterward.  Using the software that came with my Canon 60D I setup to take 32 exposures at 2 minutes each with ISO set to 1600.  When the first image downloaded 121 seconds later my first thought was "Holy #$!%&- $#!+". Only it wasn't a thought.  It took me a second to realize I'd just used the big boy voice in expressing my appraisal of the Hyperstar's capabilities.  It hooked me into a hopeless, debilitating and pathetic obsession that continues unabated to this day.  As I think about that first night now, I look back with an appreciation of the things I did right and reflect on the the things I didn't. 

The Mount

If you've been around the imaging game for awhile you've heard it a thousand times - "The mount is the most important piece of astro equipment".  If you're a total newcomer say it out loud a thousand times - "Without the mount, I have nothing".  Except for starlight the mount is the most important ingredient in astrophotography.  I know this now to be true.  I started out with a Celestron CGEM and an 1100HD optical tube.  I did this because I was sure that I was going to also use the 1100HD for visual astronomy and I wanted the large aperture and long focal length on a go to mount for visual observing.  I was as wrong as a punch in the face.  I put an eyepiece in the telescope exactly twice.  Once the first night I set it up, and once when I was 100 miles from home deep in the Kofa National Wildlife Refuge only to realize my laptop was sitting on the kitchen table.  It did a servicable job of imaging with the Hyperstar at 560mm of focal length but it was at the absolute limit of acceptable weight.  It wouldn't have been up to the task - even a little - of imaging at prime focus through the 1100HD. 

I upgraded a few months later to a beefier, more serious mount - a Celestron CGE that I purchased second hand from a good friend.  It carried the weight of the Celestron much better but it was finicky.  With both Celestron mounts I was always managing the mount.  I wanted to get to a place where I could just turn the laptop loose and I could go back to visual observing with my 15" Obsession.  I got the mount Hypertuned which helped immensely.  The imaging sickness continued to ravage my tender little psyche and I found myself online searching for an astrophotography 12 step program when I stumbled across a site by a company called Astro-Physics.  Okay...maybe it didn't really go down like that.

By virtue of having a very good year professionally I was in a position to start looking for that "lifetime mount" and I spent several evenings in a row just poring over the German Equatorial Pornography websites of the AP900 and Paramount MX.  After about the third straight evening doing so, my wife walked by and simply said..."Would you just buy one already and be done with it?"  I've said it before - Greatest Astronomy Wife Ever.  As I've mentioned before I ended up buying the AP900.  I chose it over the Paramount MX for one simple reason - instant gratification.  The Paramount had a 4+ month wait for delivery.  The AP900 could be in my backyard in 5 days.  Had they been the same, I would have purchased the Paramount.  Interestingly enough - now that I'm familiar with both - I think I made the better choice. 

Since incorporating the AP900 things have gotten so much simpler.  No longer do I have to babysit the mount.  Not even a little.  Since implementing CCDAutoPilot I will go for days at a time without touching the mount.  I uncover it in the evening and start the imaging run.  I'll recover it in the morning.  At the next sunset I repeat the process.  It guides like a dream.  My friend Bruce who isn't an amateur astronomer took one look at the mount and called it "industrial art".  It's a perfect description.  Without plugging in the hand controller or using a polar scope I can set the mount up at sunset and be drift aligned to an arc minute of the north celestial pole before astronomical twilight.  In a future post, I'll detail how to do that. 

What I would say to the newcomer is to invest in the mount.  This is not new information but it's worth repeating.  Premium mounts like Takahashi, Astro-Physics and Paramount turn up on Astromart with semi-regularity and can be bought at a discount to the new price.  They're great quality mounts and hold their value well.  With the introduction of the AP1600 and the Paramount MEII, I expect to see a host of AP1200's and Parmount ME's turning up at reasonable prices.  It'd be a great time to buy one.

Shortcuts are a Long Road to Misery

It's a process.  If you try to shortcut the process, you will invariably make it harder and more frustrating on yourself.  Don't take shortcuts.  My many years of experience developing processes and software designs to use them in a business environment has certainly aided me in my imaging pursuits.  The path of least resistance is a disciplined, methodical and repeatable approach to data collection and image processing.  If you don't possess at least a minimal amount of that skill....deep sky imaging will be a frustrating process until it teaches you those skills. 

Don't try to compete with the Hubble your first night out.  Point the camera at the sky and take a picture.  That's what I did when I created the greatest astrophoto ever taken.  Now, build from there.  Incorporate additional pieces into the puzzle one at a time.  Develop a step by step plan for setting up the telescope, aligning the mount, focusing and gathering data.  Don't deviate from that plan.  It's when you deviate from the plan that bad things are more likely to happen.  Make no mistake - bad things are going to happen no matter what.  My beloved Red Sox spent 86 straight years learning that.  They're less likely to happen and easier to troubleshoot when you have a basic process for collecting the data. 

Use the full moon and your light polluted back yard to your advantage. You're thinking I've lost my mind....but it's the best time to learn more about imaging.  Most of us have to pack up the gear and take it far into the desert/woods/plains in order to get dark skies and quality data.  With a trip that long and time under the dark sky so precious - this is not a good time to begin experimenting with new techniques or attaching a new piece of equipment.  Do that stuff at home, in your backyard during a full moon.  I make it a point that I don't ever try a new piece of equipment or change up my routine at a dark site unless I've already tested it at home under my light polluted skies.  That's what the backyard and full moon are for - experimentation and learning.  You won't get awesome data in most cases, but you're not trying to - you're trying to develop your skills. 

What's the best way to develop your skills?  I'm glad you didn't ask!! It's formal testing.  Make a list of things you want to try when you get out to the backyard....seriously, write it down.  Jot down some steps - again, in writing - that you're going to take when you do that test.  Finally, write down next to it exactly what you expect to achieve.  Now go out in the backyard and execute those tests step by step exactly as you wrote it down.  If you don't get the results you anticipated, figure out why.  This is the fastest way to learn new equipment, new software and to identify holes in your own process.  It makes the best use of your backyard time.  This is especially effective with the software we use to capture this stuff.  It'll help you learn it that much faster if you script out your tests.  An additional benefit is that when you get out to a dark sky you'll more intuitively know what you need to be doing and you'll come home with more better gooder data than before.

The Telescope

I've said a hundred times that I don't think there's a better way to develop some imaging skills than Hyperstar attached to a Celestron SCT.  Problem is that it's a really expensive way to start learning if you don't already have the optical tube assembly.  And my own opinion is that a Schmidt-Cassegrain telescope is about the worst option for long focal length I don't love the idea of imaging with an SCT without Hyperstar.  At f/2 the Hyperstar collects lots of data and it does it really fast....allowing you to focus on developing your process and adding the other things that are part of this hobby one thing at a time.  You don't have to be totally accurate with your polar alignment to start shooting 30 second subs.  This gives you some incentive to learn polar alignment so you can shoot longer subs....but you'll still get useable data back while you're working on it.  Soon you'll be able to shoot for a couple of minutes and you'll want to add an autoguider; and then autofocusing; and then plate solving;  You see where I'm going with this....

But looking back now, if I had understood that I would never be using that 1100HD visually I think I would have saved a lot of money and been just as happy with a quality short focus refractor.  Explore Scientific, Orion and a couple of other vendors make a nice 80mm APO refractor that I think would be just about the ideal beginning imaging scope.  My own goal is to get to longer and longer focal lengths for high resolution deep sky imaging.  I started at 560mm focal length and then went to 950mm focal length.  Soon perhaps there'll be another move to longer focal length and larger image scale.  Start with a telescope that's going to make it easy and move up from there.  Again, you can use Astromart as your friend here.  If you buy a quality scope used at the right price on Astromart, you can get close to what you paid for it back when you upgrade to a longer focal length.  In fact, you'll probably be able to get a longer focal length scope at a fire sale price from someone who insisted on shortcutting the learning curve and is now abandoning astrophotography because he can't figure out how to take a decent image at longer focal lengths. 

The Camera

I started out with a DSLR and quickly made the jump to a one-shot color CCD camera.  In early summer last year I sold the color CCD and bought a mono CCD, filter wheel and filters.  If I had it to do over again with the knowledge that I have no I wouldn't have purchased the color CCD camera.  I would have gone straight to the mono and filter setup.  If you have a look at my Astrobin page you can see very obviously in mid 2012 where I made the switch from OSC to mono CCD and filters.   Cutting the color CCD out of the equation would have saved me some money and shortened the learning curve a bit I think.   

Finally, the Future

Now that I'm two years in, what does the future hold?  Here's where I see it all going for me in the next year:
  • Longer focal length - I'm in love with refractor imaging so I'm getting into that rareified air where optics price and OTA size start increasing exponentially.  If I'm going to get to much longer focal lengths I'll probably have to find a way to appreciate diffraction spikes.
  • Remote imaging - I have my setup automated with CCDAutoPilot and when I'm home or in the field it runs all night every clear night.  Locating the gear in a remote, dark sky site accessible via Internet will allow me collect data every clear night even when I'm on the road traveling for work.  I'm actively pursuing this now but I haven't settled on a location yet.
  • PixInsight - In an effort to give something back I hope to use this space to start posting some shorter tutorials that demonstrate how to do various tasks in PixInsight.  It's an amazing platform.
  • Visual observing - I love observing and I've been able to get back to doing some of that now that I have the rig playing nicely most nights I setup.  Locating the gear remotely will allow my new moon desert trips to become strictly visual affairs. 
Stay tuned for the next edition of my blather where I'll talk about the AP900 or maybe a PixInsight tutorial.  Or none of that.

Jan 23, 2013

Two Years In - What I've Learned

Dec 2010 - The Greatest Astrophoto Ever Taken
I'm coming up on 2 years of deep sky astrophotography now, and as is the way of my people, it brings about some reflection on where I've come from and where I'm going with this whole thing.  You may remember that I did this a year ago on these very pages when I debuted the undisputed Greatest Astrophoto Ever Taken.  It's visible at left in case you've forgotten the awesome stupendousness of that image.  As technically perfect as that image is, it's even more interesting to me that it was the first image I'd ever taken.  Seeing the image come together as I stacked up the frames and attempted to do some basic levels adjustments lit a new passion for me that continues unabated to this day (which is a Wednesday).

Dec 2010 - My first "true" deep sky image.
Orion has been a common theme in my first couple of years as a deep sky imager.  I thought I'd use this entry to take a look at those images chronologically.  I'll document as well the processing steps that I took on my final M42 image.  To the right is my first attempt at a deep sky object.  I shot the M42 region with a cheap telephoto lens piggybacked on top of my telescope from my Goodyear, Arizona backyard.  

Time to Get Serious

Jan 2011 - This is what happens when you allow
someone to PhotoShop unsupervised.
 My piggyback astrophotography phase lasted about two weeks before I took the plunge and added a Hyperstar to the imaging rig.  Seriously, I don't think it lasted that long.  I captured exactly four images as a piggyback astrophotographer before this obsession drove me to longer focal lengths.  My first night out I shot (naturally) M42.  This time it was with the DSLR strapped to the front of the CGEM 1100HD and Hyperstar.  By this time I had invested in PhotoShop CS5 and had learned just enough about image processing to mangle even the most pristine data.  As you can see, I knew how to stretch the data and even a little about how to layer mask poorly.  You can also deduce that I either knew nothing yet about color balance or that I am color blind.  Thankfully, it was a lack of understanding on how to balance color. 

Apr 2011 - The same data after some learning.
For the technically interested, the image consisted of 32 subexposures of 120 seconds each and 32 subexposures of 10 seconds each.  MaximDL was used for capture, calibration and stacking and all subsequent post-processing was done in PhotoShop CS5 using my extremely limited image processing talents.  For the artistically interested and all those praying for a happier ending to that photo, I took some classes.  I read through PhotoShop Astronomy which was somewhat helpful.  I picked up Ron Wodaski's Astro Zone system which was more helpful.  Incidentally, I think OPT is the only place that you can get it anymore.  What I found most helpful though was signing up and going through Warren Keller's IP4AP tutorials.  It was his tutorials that helped me turn the same data into something more realistic.  This image is the same data, just processed much better. 

Nov 2011 - Cooled CCD and a year of experience
make for a much better image.
You can see though that the color is still lacking.  This was being caused by my unmodified DSLR and I soon took the plunge into the realm of the CCD camera and bought a QHY8PRO from Astrofactors.  After breaking it in on a bunch of other images, I shot M42 once more with the Hyperstar and CCD in November of 2011. Then, as now, I wanted to compare what I could do with my earlier attempts.  I think this was a vast improvement.  I had learned much more about layer masking, color balance and getting more out of the data.  Let me first say that I don't think there's a better way to get into deep sky imaging than Hyperstar.  It makes it so much easier to get a lot of good data quickly.  It's so fast that it allows you to add the other pieces of the puzzle like autoguiding and drift alignment one at a time.  Having said that, it was at this point that I began to feel limited by the Hyperstar.  A month or so later, I began shopping for a refractor and longer focal lengths.

2012 - It Ain't Broke; Fix it!

It really wasn't broke, but my long term goal had always been to get to longer focal lengths and high resolution deep sky imaging.  Over the course of 2012 I have managed to overhaul the entire imaging rig.  I changed the mount to an Astro-Physics AP900.  I changed the imaging telescope to an Explore Scientific ED127 Triplet.  I sold the one shot color CCD in favor of mono with an SBIG ST-8300m.  I added an off axis guider and 8-position filter wheel.  Into the filter wheel I stuffed a full complement of Astrodon broadband filters and Astrodon 3nm narrowband filters.  Early in the year I tried out the PixInsight platform and fell in love with it for image processing.  I have now reached a point where all of my post-processing is done in PixInsight.  I haven't used PhotoShop CS5 for any part of the processing in probably six months.  Of course, I can't leave well enough alone so I added CCDAutoPilot to the mix in an effort to completely automate the imaging rig which has been a great success.

My middle daughter had surgery to remove her tonsils and adenoids at the end of December 2012 and I took some time off work to stay home and be some moral support for her and to help her recuperate.  At 16 years old it's not as simple of a procedure as it is when you're much younger.  She did great though and is back to her 100% self eating hamburgers and all kinds of other awesome food with me.  She had mentioned that the Orion Nebula was her favorite deep sky object so I thought it would be appropriate to capture it while she recuperated.  I wanted to do it at least a little bit different and I was shooting from my light polluted backyard so I went with a narrowband image and processed it in the Hubble palette.  I shot 4.5 hours worth of data and put the image together.  I realized then that I had a really nice image going so I extended the project to collect significantly more data.  The final result is shown below.

M42 - 19 hours in the Hubble Palette
I collected 19 hours of narrowband data between December 17th and January 4th and then put it all together into the image shown above.  What really impressed me with this image was the amount of detail that I was able to record using just a 127mm refractor.  The detail in M43 and the dust lanes that separate the two Messier objects draws my eye each time I look at it.  My daughter calls it my best work yet.  She immediately found the "soap bubble" in the right center of the image - something I hadn't noted previously.

PixInsight Processing Steps

  1. Data Calibration - I use the method described in Vicent Peris' tutorial to create master calibration frames and calibrate the data.  I calibrated 106 subexposures in total with subexposure times of 30 seconds, 3 minutes and 30 minutes.
  2. Image Integration - I stacked each filter/exposure separately and saved the files in a FITS format.  I had 9 files total - 3 subexposure lengths each of HAlpha, OIII and SII data.  As typical in the Hubble palette, I mapped SII data to the red channel, HAlpha data to the green channel and OIII data to the blue channel.
  3. Channel Combination - I created an RGB Master of each subexposure length.  So I ended up with a 30 second RGC, a 3 minute RGB and a 30 minute RGB master.
  4. Dynamic Crop - I cropped the image to remove the ragged edges from stacking a set of dithered frames.
  5. HDR Composition - This is just an awesome tool built into PixInsight.  It does a linear fit of the three images and then combines them in much the same way that you'd do it manually with a layer mask in PhotoShop.  Truly awesome stuff here.
  6. Create a Luminance Master - Extracting the luminance and saving it as a separate master, I proceeded to process the image as a normal LRGB.
  7. Multiscale Median Transform - I created an inverse luminance mask and then did MMT solely to do noise reduction while the data is still in a linear, unstretched format.  This noise reduction allows me to push the image more when I stretch the data.
  8. Histogram Transformation - PixInsight's fancy word for stretching the data.  It's crazy simple to use and ridiculously effective. 
  9. HDR Multiscale Transform - Compressing the data in specific wavelet layers does a great job of pulling out the data that's being overwhelmed in the Trapezium.
  10. Local Histogram Equalization - Using a luminance mask and running this process restores some contrast that is lost in the wavelet processing above. 
  11. Multiscale Median Transform - Again, using a luminance mask designed only to allow the process to work on the highest signal areas, I used MMT this time to do some sharpening on the luminance frame.
  12. LRGB Combination - Finally, I combined the luminance with the RGB master and did some final tweaks to the histogram, color balance and saturation.

Synthetic RGB

After I'd completed the image, I did a final step with the Pixel Math tool in PixInsight and recombined the channels in an effort to create a realistically colored image using only the narrowband data.  I could probably play around a bunch more and get it really close.  This will have to suffice though.  I'm really happy with it. 
Red Channel = 70% HAlpha + 30% SII
Green Channel = 25% SII + 75% OIII
Blue Channel = 70% OIII + 30% HAlpha

If you've stayed with me this long, thanks!!  After this one, I think I'm done shooting M42 for awhile.  There's a lot of other objects out there that I want to shoot.  I'm really happy with my progress in the imaging arena and I feel like I'm starting to turn out some really good astrophotos.  Next time, I'll offer advice I wish I could go back and offer to myself.  I hope you'll stick around for that and that you'll find it helpful as well.