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 imaging...so 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.