Nov 5, 2012

Test Report: Explore Scientific ED127 Carbon Fiber Apo Refractor

Before we start, let's just get the obvious question out there right now.  You're wondering: "What makes this guy qualified to review any sort of equipment?"  It's a pretty simple answer really.  I have an opinion, a few minutes and a keyboard.  Those are the extent of my qualifications and I possess no other.  If you came here expecting me a dissertation on refractor theory and to debate the finer points of chromatic aberration and glass types at some nauseating level of tedium, you have come to the wrong place and should stop reading now.  I am not that astronomy creature that I refer to as "refractor guy". 

You know him.  He's the one who takes his refractors far too seriously and is ready to escalate any discussion on the topic to a Defcon 5 incident.  Casually drop the phrase "TeleVue scopes are overpriced" and you'll awaken to find that he's kidnapped your dog (dognapped?) until you publish a retraction of such heresy.  If you don't know that guy, you should swing over to the refractor forum on Cloudy Nights.  There's a few of them there.  After you've done that...if you still don't understand what I mean by "refractor guy" - then you're probably "refractor guy".  Please don't think that I'm picking on "refractor guy".  He's not the only eccentric personality in this hobby.  There's also Celestron guy, Zambuto guy, Double Star guy, Binoviewer guy, etc.  It's part of what makes our hobby obsession so great. 

How Did I Get Here?

I reached a point late last year where I was ready to move into some longer focal lengths for deep sky imaging.  I'm also not a fan of diffraction spikes in an image and the wiring hanging down in front of my Hyperstar rig was causing them with no real way to get rid of them.  Finally, with the Hyperstar I did find it difficult to get pinpoint stars all the way across the APS-C sized sensor of my QHY8PRO CCD camera.  One corner or another was always out of focus and it was a constant battle with collimation.  In summary, I'm a huge fan of the Hyperstar system.  There isn't a better way to develop some chops in this thing we call deep sky imaging and it makes it easy for a newcomer to get good images.  However, it was time for me to move on.  Back in December of 2011 I was curious to experiment with a refractor, and I had an 80mm f/7.5 Vixen doublet that wasn't being used right at that moment.  So I put it on the mount and shot a dozen frames of the Double Cluster through it.  I was blown away at the increased color saturation and the pinpoint stars through the refractor.  I knew then that the new imaging scope would be a refractor. 

Double Cluster as shot with an 80mm Vixen refractor.  This shot convinced me to shop for
a refractor as my next imaging telescope.  Just 12 frames x 2 minutes at f/7.5.

I began researching refractors and shopping around in the 900 to 1200mm focal length.  Ultimately, I was hell bent on finding a 12" f/5 color-free triplet that weighed less than 50 pounds and only cost about $2000.  Apparently that telescope doesn't exist.  It makes me wonder what Al and Roland and Yuri have been doing with their free time, but I digress.  Soon I began to assemble some realistic expectations and narrowed the field.  I had the good fortune last summer to meet up with my friends Alan and Jerry where they had setup their respective refractors and I was able to compare them visually side by side on similar objects at similar magnifications.  Alan's TEC 140 is just a gorgeous scope and it renders me as useless as a teenage boy at a lingerie convention every time I see it.  The views through the telescope are just astounding and I've become a better visual observer from using it and letting him teach me how to tease out detail in the objects that are being viewed.  But at nearly $6000 by the time you buy it, ship it and put it on the mount, the TEC 140 is expensive. Nearby, Jerry had setup his brand new Explore Scientific ED127.  With its 5" aperture and carbon fiber tube it was an attractive scope in its own right - especially at its introductory price of $1999. 

After a long night of comparing views and enjoying the company, my friend Chris put it all into perfect perspective.  His review (and I paraphrase):
"The view through a TEC 140 is better, there's no question about it.  But, the only thing wrong with a view through Jerry's ED127 is that it's sitting next to a TEC 140.  And the only thing wrong with the view through Alan's TEC 140 is that I'd be just as happy looking at the same objects through an ED127 with $4000 in my pocket."
Artist's conception
of Refractor Guy
Let's pause for a few seconds while "refractor guy" finishes hyperventilating.  Breathe into a paper bag refractor guy.  Apparently, it helps. I couldn't write a better comparison myself and it's this exact reasoning that led me to choose the Explore Scientific scope as my new imaging platform.  Now before you start penning me that email that says I have no qualifications whatsoever - please remember that I started out this review by admitting that.  Please save your breath telling me that I'm an idiot.  I've been aware of that far longer than you have.  Chastising me in any way for this opinion/decision will introduce no new information to this topic other than to possibly identify you as "irrational refractor guy".  If the budget had allowed for a $6000 refractor at the time I might have made a different decision, but I doubt it.  All better now?  Good. 

Acquiring The Glass

I pondered and debated the decision over a weekend in early January.  In other words, it took me two days to work up the courage to pry open my wallet and dig out the debit card to place the order.  It's not that I had to await approval from the "CFO" like so many other fellow amateurs have to do.  In fact, I should do a review on my lovely and talented spouse and her suitability as an "astronomy wife" some day;  Best astronomy wife ever - I'll tell you that.  I just agonize and worry and fret the decision to purchase astronomy gear before I buy it.  Once I pull the trigger, I don't worry about it again.  On Sunday morning I pulled the trigger on the refractor.  I got out of bed and placed my order with Oceanside Photo & Telescope with a cup of coffee in one hand and the computer mouse in the other.  Just so I can paint the complete picture, I have to say that I was rocking the most astounding case of bed-head that you've ever seen while I placed this order.  My research had indicated that the large chip of my CCD camera would probably be happy with a field flattener too so I also ordered a Hotech SCA field flattener and a Baader Vari-Lock extension to get the spacing right with my camera.  Both were a wise addition to the purchase.

OPT listed that they had all of the items in stock and that there would be no shipping charges.  As you can see, I started my Sunday off the right way.  By virtue of its stock status I received a tracking number for the shipment the next day indicating that it would be delivered on Wednesday.  Of course, this clearly means that it's imperative that I work from home on Wednesday and that is what I did.  The UPS man delivered the packages very, very late in the day on Wednesday.  This served to reinforce "Mike's Postulate of Astro Equipment Delivery" which states:
If you remain at home awaiting the delivery of exciting new astronomy gear, your package will be the last delivery of the day;  Even if you live across the street from the UPS warehouse and your mom is the driver. Unless you run out for something during the day, then they'll attempt to deliver it while you're gone and you'll end up waiting and being the last delivery of the next day.  This is still true even if you live across the street from the UPS warehouse and your mom is the driver.
The scope is sold with its own case and is packed in that case for shipping.  All the edges of the scope's storage case are lined with heavy foam that helps it fit perfectly into the heavy cardboard shipping box.  I was a little surprised at the weight of the box - heavier than I expected.  I'll spare you every little detail of the shipment.  The box had a couple of dents in it from its transport from China to the US to my house, but the contents on the interior were in perfect condition upon arrival. 

The Case

The case is nice.  It's solid, durable and protects the telescope very well.  It's cut to form fit the OTA as well as the diagonal and finderscope.  There are some additional cutouts to store a couple of eyepieces.  The case is far above and beyond what you would expect in quality for a telescope at this price point.  Problem is, it's almost too good.  The telescope fits so tightly into the case that it has to be put in "just so" in order to fit and have the lid close properly.  With my 2.5" Moonlite focuser attached to the scope it is an extremely tight fit to get the OTA in there.  With the new camera I had to order a focuser extension to get the required out-travel and the scope no longer fits in the case.  Overall though - I'm a fan of the case that came with the scope. 

The Mount

The telescope is light.  In my case it was actually too light by an ounce or two when I first took it out.  Let me explain.  The scope comes with rings and a Vixen style mount that fit nicely into my ADM dual saddle on my previous Celestron CGE mount.  Even with the cameras and finder attached, the telescope was so light that I couldn't completely balance the scope.  I had two of the standard counterweights with the CGE and definitely only needed one.  Even with a single counterweight I had to slide it as far up the shaft as possible.  I slid a piece of cardboard in between the weight and the DEC housing to ensure that they wouldn't hit each other while the telescope slewed.  Still, the telescope was a couple of ounces too light to completely balance.  If I was to keep the mount balanced "east heavy" I had to image only in the eastern sky as the telescope was too light to image in the west and keep the scope "east heavy".  I feel more comfortable with the wider plate and surface area of a Losmandy style dovetail anyway, so I remedied this soon thereafter by mounting the scope with an ADM Universal D plate.  This added enough weight to remedy the weight situation. 

The Focuser

My least favorite thing about the telescope is the focuser that is attached to it.  For visual use, it is probably more than adequate.  I wouldn't know.  I didn't buy the scope to use it visually and I haven't done so.  For very light imaging trains - like a small DSLR it's probably adequate.  I bought the scope with every intention of moving to a heavy duty, computer controlled focuser so it wasn't really an issue to me.  I planned to swap it out all along.  It is a two-speed focuser and reasonably nice all things considered.  There's no way though that it would have been up to the task of supporting the weight of my SBIG ST-8300 and CFW8 filter wheel though and I don't think they're all that heavy in comparison to other imaging setups.   That said, I immediately swapped out the scope for a 2.5" Moonlite focuser with stepper motor control.  It works like a dream.

The Business End

ED127 setup for the May 2012
annular eclipse in southern Utah.
There's a couple of things to talk about on the business end of the telescope - also known as the objective lens.  It has adjustment screws to tweak the collimation, something I haven't found necessary.  The telescope was perfectly collimated when I got it and remains that way despite six months of use hauling it out to the Arizona desert a couple of times a month.  Most telescopes in this size range have a sliding dew shield that retracts for storage and extends to shield the objective lens while in use.  This isn't the case with the ED127.  The dew shield is removable and gets put onto the end of the telescope upside down to achieve the "retracted" position.  To attach the dew shield, simply turn it around and tighten down the two thumb screws to achieve the "extended" position.  This creates one minor annoyance.  In order to put the lens cap back onto the scope, you have to remove the dew shield.  I found my own solution - the LensCoat.  Since I set up typically for a few days at a time, the lens coat fits snugly over the end of the dew shield to keep dust off the objective lens when the telescope is not in use.  Now, about that lens cover.

The lens cap threads directly onto the objective cell at the end of the telescope.  It's a disc of machined aluminum and will protect the lens from all manner of dust and damage - except itself.  Thankfully my friend Jerry warned prior to the new scope's arrival at my house.  There is almost no clearance between the actual glass of the objective and the lens cap itself.  It would be very easy to hit the objective lens with the lens cap itself when unscrewing for a night's observing.  This is the only design flaw in the telescope in my opinion.  I have a pretty simple workaround though.  I mount the telescope and then move the mount so that the object lens is pointed downward toward the ground.  If I should drop the lens cap when unthreading it, this will cause the aluminum cap to fall away from the glass objective instead of toward it. 

The Tube

It's carbon fiber.  It's well finished and it's gorgeous.  The scope is attractive, lightweight and thermally stable as a result.  Some will argue that carbon fiber in a refractor is actually detrimental because it's too thermally stable and will trap a temperature differential within the tube.  I have not found this to be the case though I haven't tried to prove or disprove this information.  I do know that focus is very stable with the scope.  Over the course of an Arizona night the temperature can drop by as much as 50º F (28º C) in the winter.  I refocus the telescope every 2 hours and haven't yet lost a subexposure because of the image being out of focus.  Between the wide critical focus zone of f/7.5 and the thermal stability of the carbon fiber, those frequent stops to refocus the telescope are a thing of my past and I'm glad for it.

Flatness of Field

To satisfy my own curiosity, first light with the scope involved a series of exposures taken with and without the field flattener.  You can see the results below when the camera uses an APS-C sized chip.  To my eye, the field flattener is a required accessory for anyone wanting to use a DSLR or similar sized chip with this telescope. 

I've recently switched from the QHY8PRO to the mono SBIG ST-8300 CCD camera.  Before pulling the trigger on the camera I did some analysis and made the estimation that the flattener wouldn't be necessary with the smaller chip of the SBIG camera.  I judged this by cropping the subs from the test shots taken without a flattener down to the size of the KAF-8300 sensor and to my eye stars look alright.  Actual experience has shown that the flattener is necessary even with this smaller chip.  So if your plan is to use the scope for imaging, plan on a few hundred extra for a field flattener, just as you would with any other refractor.  I've heard rumor of an upcoming release by Explore Scientific of a dedicated field flattener for this scope.  Since I've never actually seen one or even a picture of one, I have this information filed between BigFoot and Unicorns on my list of things that are real.

Color Correction

This is where the refractor discussion gets touchy.  Here's what I know.  The telescope is a triplet which is supposed to provide excellent color correction.  To my eye it does that.  The difference in focus between the blue filter and the red filter in my imaging setup is 57 steps on the focuser - which equates to 234 microns of travel.  Since the critical focus zone of an f/7.5 refractor is something around 170 microns, I'd say that this means that there's a bit of color in the image.  Since I image with a mono camera and focus for each specific filter, this hasn't been an issue for me. 

Abell 85 shot with the ED127CF.  Seems like pretty good color to me.


Overall, I'm very happy with the telescope and will probably be holding onto it for awhile.  I really mean this - but if you've followed this blog for any length of time - you know that I've shown a tendency to mysteriously upgrade equipment just when I say I like it.  With two teenage daughters at home expecting their first car soon, I'd say there are external factors at work that'll keep this scope in my possession.  I understand that Explore Scientific has made some changes in the newer models - a beefier focuser and a sliding dew shield.  Both of those changes make me recommend the scope even more.  It's worth every penny.  It's not my last scope, but that's because my goal is still to get to longer focal lengths for some really deep sky imaging.  I don't think that there's a better refractor out there for $2500.00.

Oct 31, 2012

NGC 6914 - Seeing Red


My emphasis on the Hydrogen Alpha data and its use in the luminance
had the intended effect on the detail, but it cost me a lot of the 
reflection nebulosity that's in this nebula complex.
Over the last few months as I've been working to get all of the new equipment from the summer to work together.  I have to say, it wasn't difficult.  I had it all lined out and behaving very quickly. The SBIG imaging setup has performed without a hitch in all that time.  With my implementation of CCDAutoPilot I have been able to massively increase the amount of time that I spend imaging.  Much narrowband data gets collected from my Arizona backyard while I sleep.  During weekends at dark sky observing sites, CCDAutoPilot takes over the equipment and I just forget about it.  It's allowed me to return to visual observing when I'm out on those new moon weekends. 

NGC 6914 is a huge nebular complex in Cygnus.  It's one of those great star filled areas of sky that feature all three types of nebulosity (emission, reflection and dark) in one field of view.  Having seen images of it previously, I wanted to focus specifically on the hydrogen alpha data and the contrast between the emission and dark nebulae in the area.  

Gathering the Image
The imaging rig all setup for the
magnitude 7.5 skies of Portal, AZ.

I started data collection on NGC 6914 in late August.  I cut my teeth on CCDAutoPilot with this object, ironing out the small learning curve and getting all of the software to play nice together.  A handful of subs were lost early on, but it only took a couple of sessions to get everything running like clockwork. 

I live on the far outskirts of the Phoenix metro area, so there is moderate light pollution at my home.  This was the real reason that I wanted narrowband filters - to collect that data from my backyard where it's relatively unaffected by light pollution.  All of the hydrogen alpha data was collected there.  It was this data collection that revealed one shortcoming of my SBIG ST-8300 camera. 

In August and September where I live, temperatures even at sunset are still usually well north of 100ºF (38ºC).  Overnight lows rarely drop below 85ºF (29ºC) during that time.  As a result, it was absolutely impossible to cool the chip of the ST-8300 to anything below 0ºC.  Thermal noise was a huge factor in the 30 minute subexposures that I captured for the hydrogen alpha data. Thankfully, a good set of 30 minute dark frames captured at the same temperature did a good job of minimizing the noise.  Still, I have to believe that it has an impact on the final outcome.

A September trip to a dark sky site in the shadow of the Discovery Channel telescope at 6800' elevation was used to capture the RGB detail.  I began processing the image fully intending that I would use just the H-Alpha data for the luminance channel.  I couldn't achieve an image that I felt was even vaguely good because of the big difference in star size between the H-Alpha and RGB data.  During the October trip to Portal, Arizona I supplemented the H-Alpha with some quality luminance data. 

Over the course of many nights, and three different locations in Arizona I collected just shy of 20 hours of data for this image.  Here's the breakdown:
  • 28 x 1800s - 1x1 bin - H-Alpha 3nm bandpass
  • 10 x 600s   - 1x1 bin - Luminance
  • 16 x 300s   - 2x2 bin - Red, Green and Blue (each) 

Image Processing

I made use of a couple of tools specific to PixInsight to great advantage when blending the H-Alpha data with the rest of the image.  I used the HaRGB combination script to combine the H-Alpha with the rest of the color data.  I wanted also to use the H-Alpha as part of the luminance, so I ran the HaRGB script again with slightly different parameters:
  • I created a new "RGB" image, but used the luminance data for the R channel.  Essentially, I created an LGB.
  • I ran the HaRGB combination script to blend the Ha with the "red" channel of the LGB image.  This accomplished my task of blending the Ha and L channels.
  • Using the Channel Extraction module, I extracted the R channel and threw away the other two.  This gave me a luminance channel that had all of the H-Alpha detail and star sizes from the luminance data.


Aug 7, 2012

SBIG's All Up In Your Grill - First Light

NGC 6888 - Crescent Nebula

NGC 6888 as captured with the new imaging equipment.  SBIG cameras, filter & off axis guider utilizing Explore Scientific optics.
So the Arizona monsoon let up enough over last weekend long enough to allow me to setup the equipment and take some serious first light images.  Once I got the mount polar aligned I left it setup for the next four days - just taking the optics and cameras off each day as the sun rose above the eastern horizon. As you may remember from my recent discussions, I have a lot of hardware and software changes that I've been trying to incorporate all at once.  As a result, this session didn't go completely trouble free, but it was darn close all things considered.  Even since writing those articles I went ahead and pulled the trigger on the SBIG OAG-8300 off-axis guider and the SBIG ST-i mono guide camera.  So far I'm happy with the two of them but there are a couple of minor annoyances that I didn't expect at this price point.  That's another topic for another time though.  Over the course of the four nights I was able to get the entire system integrated and working the way that I want it to work.  All I'm left with now is minor tweaks here and there.  

Gathering the Image

When I saw Manuel Jimenez' image of NGC 6888 last year I knew that it would be my first image if I ever got into narrowband imaging.  It was that simple selecting my first light target.  I didn't expect that I'd get anything near that awesome considering I'm not rocking $100,000 of equipment that includes a 17" Planewave CDK.  I was curious if I could capture some of the same detail with a 5" refractor.  All things considered, I'm really happy with the performance of the Explore Scientific triplet.  I'm working on a full review of it - but I'll just say that it doesn't get enough love in the astronomy community.  It's been worth every penny I paid for it - and it wasn't very many pennies comparatively.

Over the course of the four nights (and days) I managed to pile up 16.5 hours of light frame data using two filters - Hydrogen Alpha and Oxygen III.  Here's the breakdown of all the data that went into the image:
  • 17 x 1800s Light Frames - 1x1 bin - Astrodon 3nm H-Alpha filter
  • 16 x 1800s Light Frames - 1x1 bin - Astrodon 3nm OIII filter
With the exception of a noise reduction plug in (Neat Image) that requires the use of Photoshop CS5, I did everything after the capture using PixInsight 1.7.
  • Created master calibration frames - Bias, Dark, Flat & Flat Darks
  • Calibrated, registered & stacked the light frames with Winsorized Sigma Clipping
  • Using Pixel Math I generated a synthetic green channel that is a mixture of 25% H-Alpha and 75% OIII data.
  • I combined the images as a traditional RGB and processed as normal.

What I Like - and What I Don't

I've come to accept that there will always be things I don't like about one of my images.  This one is no exception.  But overall, I enjoyed putting this one together as much as anything I've ever done in astronomy.  The data was excellent and I couldn't be happier with how it came out in the end.  Okay, yes I could.  But considering the factors involved in gathering the data I'm as happy as can be.  I'm also a firm believer that we don't learn from our successes, we learn from our mistakes.  And thus, a constructive critique is the best way to really improve - so on to what I don't like.

Field Curvature - If you click on the above image and look at the larger size, it's pretty apparent looking toward the edges that there's a good amount of field curvature.  This is self inflicted.  I had hoped to be able to use the ST-8300 without a flattener and my calculations told me that it would be close but acceptable.  I was wrong.  Because the cameras, filter wheel and OAG combined weigh 4.5 lbs (2.1 kg) I don't feel comfortable depending on three thumbscrews and a compression ring to hold the equipment.  Right now the imaging rig is all threaded connections from telescope to camera and there's no flexure.  So I guess I'll start looking for a solution that incorporates a field flattener into the mix while keeping my 100% threaded solution.

Noise Reduction - I overshot it a bit on the noise reduction.  The image is "too smooth" to me.  In my defense, I was shooting in the lower deserts of Arizona from my backyard.  Daytime temperatures were approaching 110º F (43º C) and the lowest night time temperature I saw was in the upper 80's (about 30º C).  This limited the amount of cooling that I was able to get from the camera and the entire image was shot with the TEC sat at 0º C.  The images had huge amounts of thermal noise in a 30 minute sub.  A good set of darks certainly helped but the starting point for post-processing was a pretty noisy image to begin with.  I expect I'll have a much better result when I get the camera in some cooler ambient air - hopefully soon.

Jul 18, 2012

Taking Stock – The Software

Last time out I covered the hardware, which looks all pretty and imposing when it’s all setup – but it’s exactly half of the equation.  It’s the software that makes modern astrophotography possible.  In my own setup, the software plays a critical role in every step of the process from setting up to publishing a finished image.  In this second installment I’ll finish detailing the pieces of my imaging rig that all contribute to the end result and how it all fits together.  From this point forward it’s my hope that I can start tackling some specific tasks and how I handle them when it comes to deep sky imaging. 


PEMPro is designed to a do a handful of things – chief among them is to measure and program periodic error correction on a telescope mount.  It excels at this task and I had excellent results using it on both of my previous mounts.  On my original Celestron CGEM I had a native periodic error of 17.6” peak to peak.  A couple of hours with PEMPro and I was able to program the mount with a curve that reduced it to 3.1”.  It helped me similarly in taming my Celestron CGE (52.1” down to 4.3”).  As I detailed in the last post, my Astro-Physics AP900 has a native periodic error of 1.45” peak to peak.  I haven’t bothered to even try and improve that yet.  Interestingly, Astro-Physics uses a specialized version of PEMPro to measure and program the periodic error in their mounts prior to shipping them out. 
For me though, PEMPro’s greatest strength is in the Polar Align Wizard that is another of its functions.  I don’t have a permanent observatory so I’m setting up and aligning the equipment every time I go out to image.  I’ve managed to arrange my imaging rig and the setup workflow in such a way that I can be polar aligned well enough for 30 minute sub-exposures before the end of twilight.  PEMPro’s Polar Align Wizard is a huge part of that.  Essentially, it’s a computerized version of drift alignment that works as follows:
  • A quick routine is used to determine the camera’s orientation (position angle) and the calibration of North/South/East/West to the X/Y coordinates of the camera chip.  Typically this takes me about 2 minutes. 
  • PEMPro will measure a star near 0º declination and near the meridian by taking repeated subexposures and measuring the star’s drift over a period of time.  Typically, I do this for 7 minutes.
  • After selecting a star in the star field, PEMPro will draw an arrow and a circle over the frame and begin taking repeated images of the field.  Using the azimuth adjustment you simply adjust the mount east/west until the star is in the circle drawn. 
  • Altitude is then set by moving 45º relative (east or west) to the meridian and repeating the 7 minute measuring phase. 
  • After selecting a star in the star field, center it in the superimposed circle using only the altitude adjustment on the mount.
  • Repeat if necessary.
It’s that simple and takes about 20 minutes.  Typically I’m starting this process as soon as any star bright enough to see naked eye appears near the meridian and 0º declination.  As I mentioned, I’ll write a post on my entire process some time in the future.  My method gets my polar alignment to about 1 arc minute from the celestial pole before the end of astronomical twilight and a big part of that is due to PEMPro

Maxim DL

Maxim DL is one of those suite software appllications that tries to be all things to all people and it does a pretty good job of it.  Nearly everything that has anything to do with data acquisition goes through Maxim DL in my setup.  I use Maxim DL to control the telescope and the camera through every phase of capturing data.  I use Maxim DL to:
  • Align the telescope at the beginning of the evening. Using the built-in PinPoint LE astrometry software after polar alignment I can sync the telescope to a plate solved field and I’m done.  Ready to slew anywhere in the sky.
  • Slew the telescope.  Using the built in catalogs I’ll slew the telescope to the chosen object.  An automated exposure is taken after a slew and plate solved to ensure that I’m exactly centered on the field.
  • Focus the telescope.  Sort of.  I use Maxim DL to tweak the Moonlite focuser during a filter change to the appropriate offset for the filter being selected.  Real focusing chores are handled by FocusMax – which uses the camera control in Maxim DL to do it's thing.
  • Guide the telescope.  I use Maxim’s built in guiding capabilities to autoguide during subexposures. 
  • Full camera control including temperature regulation, switching filters, taking exposures and moving the telescope slightly to dither between exposures. 
  • Capture of calibration frames.  Dark, bias and flat frames are all taken with Maxim DL.  Soon I’ll be working to configure Maxim to automate flats through each filter using an Optec FlatMan.  Stay tuned for more on that.
  • Maxim DL does an excellent job of controlling the telescope to correctly capture the multiple frames needed for a mosaic. 
  • I use DDP in Maxim DL during an evening just to preview what kind of data I’m capturing.
  • Maxim DL has many other built in features for calibrating, stacking and processing images.  While they’re effective I have found that there are other tools that I like better for those tasks. 


imagePixInsight completely changed the way that I process images.  It’s software developed by astrophotographers specifically for the purpose of processing astrophotos.  It has gotten a bad rap by people who haven’t thoroughly investigated the product saying that the learning curve is steep and that educational resources are lacking.  I’ll agree that it’s a different approach to processing than most people are used to, but if you take the time to use the resources that are available it’s quite intuitive.  I use it for nearly all of my calibration, stacking and image processing.  The 800 pound gorilla known as PhotoShop still figures in to my image processing scheme for some final tweaks, but 95% of my workflow after I capture an image is done with this application.  I use it to:
  • Create master bias, dark and flat frames.  Here’s a tutorial on the creation of master calibration frames.
  • Calibrate, Register and Stack a series of light frames.  It takes more effort in PixInsight than in other applications but the end result is a much cleaner master light frame in my experience.  I stopped using Maxim DL’s calibration & stacking routines after the first using PixInsight’s methods just once.  
  • All image processing tasks including color calibration, background neutralization, stretching, contrast enhancement and teasing out detail in the image.
Expect to see some more entries into this column detailing various aspects and techniques that I use in PixInsight.  Meanwhile, if you’re interested in learning more there are abundant resources on the web.  Start at the PixInsight website.  Many tutorials are there.  Also, go to Harry's Astro Shed and start there.  I learned to process an image by taking one of my own and just walking through Harry’s tutorials.  I haven’t personally seen them myself – but I know that Warren Keller and Rogelio Bernal Andreo are working on a tutorial series at IP4AP.  I’ve seen the Photoshop series that Warren did and it is an excellent resource.  M81 and M82 shown below was the first image I processed in PixInsight. 


PhotoShop CS5

The heavyweight of all image processing packages is without question Adobe’s PhotoShop.  I once used it for everything I did in a stacked image but it has fallen very much by the wayside since I picked up PixInsight.  In all fairness though, I do still use it at the very end of my workflow to do some final background smoothing, perhaps an Unsharp Mask and to resize/save the image for publishing on the web.  There are a lot of resources available to learn how to process an image with PhotoShop.  I found Adam Block’s DVD “Making Every Pixel Count” to be the best among them.  I’ve since met Adam and had an opportunity to pick his brain on a couple of things.  He’s a gracious guy who’s more than willing to share his extensive knowledge.  Check out one of his imaging workshops if you want some hands on experience with him.

What’s Missing?

If I had to go through the rest of my life with just the equipment and software that I have I could still die a happy man.  I don’t think that I’m missing any critical piece of the puzzle any longer.  But let’s face it – astrophotographers are probably the most desperate breed of astro-equipment junkies out there.  Now that I have a narrowband imaging rig and could conceivably image every clear night from my backyard it appears that imaging could become a threat to sleep and my ability to conduct what normal people call a normal life.  I’ll evaluate the situation before long and see if it makes sense to incorporate an automated imaging platform to handle imaging sessions for me.  I’ve been quietly eyeing CCD AutoPilot to fulfill that role but I’m not a point where I’m ready to seriously take on that task just yet.

With new moon coming tomorrow I hope that the Arizona monsoon cooperates enough to allow me a solid first light with the SBIG ST-8300 and filter wheel this weekend.  Once I get that incorporated into the workflow then I’ll see about the last couple of “nice to have” pieces – an off axis guider and an automated imaging platform.  Until then,  I continue to be a happy guy who has it far better than he deserves it.

Jul 17, 2012

Taking Stock - The Hardware

My wife Toni and I with the 15" Obsession
awaiting sunset at the 2012 Grand Canyon
North Rim Star Party
Do you ever just stop and look at your life and think, "Dude!!! Life is good!!"  I've been thinking that for awhile now.  Life is good, probably better than I deserve it.  My wife and daughters are awesome to be around and I supplement them with some great friends.  Through this brutal economic downturn I've been fortunate enough to stay steadily employed and prospects for the future are looking good as well.  I've had time to get back to the outdoors which I love; hiking and camping and traveling and just enjoying the world away from the busy city life.  I get more time now than I used to for astronomy and I've been fortunate enough to put together a decent astrophotography rig over the last 18 months.  I don't say all of this to boast, it's more of a reminder to myself to really enjoy the fortune that comes my way because it can all turn in a second and be gone.  I'm grateful for everything that I've been given in this life and I treasure every moment of it.

Astronomy-wise, I've reached a point with my imaging rig that I'm really close now to what I'd call "perfect" for me.  I've reached a point where it's time to take stock of what I have and where I'm at.  I haven't written in this blog much in the last 6 or 8 months but it's not that I haven't been hard at work getting on in this life.  Read back a little ways and you'll see that what's posted here is a grand departure from what I was rocking just a year ago.  So here's what I'm at and where I think it's all going.  This time around, I'll tackle the hardware.  Next time, it'll be the software and peripheral equipment.  And then hopefully, I can start sharing some of my own tips, tricks and thoughts about that equipment in upcoming installments.  I do feel like my skills have developed enough that I can contribute at least a little bit of useful knowledge back to the imaging community.  Check back in a year and we'll see if I'm right about all that.

Visual Astronomy

The 15" Obsession awaits the advanced darkness
of Portal, Arizona's skies back in April.  My friend
Chris's 20" Obsession is in the background.
Since I took up the dark art of deep sky imaging some 18 months ago I've always had this goal that I would build an imaging rig that would be semi-automated and I would be able to collect data and observe visually at the same time.  Finally, my imaging rig is approaching that ideal and I've been able to get more time to observe with my own peepers.  For 10 years now I have done my visual observing with my trusty 15" f/4.5 Obsession dobsonian.  For me it's been the perfect balance of large aperture, small size and excellent optics.  I doubt that I will ever part with it.  As my wife once said, "It's the type of telescope that you don't sell - ever!".  In the last 18 months, I've been fortunate enough to observe with some guys who are far better astronomers than I and I've learned bucketloads from them about seeing things in the night sky.  I'm embarrassed to say that a telescope of this caliber has probably been wasted on my unpracticed eye for this long.   One day, I'll write an entire column and give this telescope a proper review.  After ten years I think I've had it long enough to give a full run down of it's capabilities and it's minimal shortcomings.  Like any good astronomer, I check out those sexy new dobs with the super short focal ratios and ridiculous large aperture all the time.  But the bottom line is that I'll never exhaust the capabilities of this scope in my lifetime. 

The Mount - Astro-Physics AP900GTO
The AP900 waits for darkness at
the May 2012 annular eclipse in
southern Utah. 

I might have mentioned in another column once how I was pretty well set on my mount for awhile with my Hypertuned Celestron CGE.  I was happy with that mount at the time - but alas, it's not an Astro-Physics mount.  The opportunity to purchase an AP900GTO came along recently and I took advantage of it knowing that I'd likely keep the mount for the rest of my life.  When I chose this mount I also considered the AP1200 and the respective Paramounts but in the end decided this was the best choice based on size, weight and availability.  I haven't thus far been disappointed.  My friend Bruce who is not an amateur astronomer called the mount "industrial art" when he first saw it. 

I've only had it out a couple of times so far, but I couldn't be happier.  It just works.  With the electronics stored in the mount controller itself, I don't have to hook up the keypad to use the mount.  I just attached the laptop to the serial connection and the excellent Astro-Physics driver controls all the interaction with the mount from either MaximDL or SkyTools.  It can be controlled from any ASCOM compliant software but those are the two that I use.  After I get a little more experience with it I'll give it a proper review.  It's been a no fuss mount so far.  When I look at my guide logs I see that the autoguider is only sending a correction to the mount about once every 45 to 60 seconds.  So what erased any doubt about the quality of an AP mount for me?  I'm glad you asked.  Periodic Error tells the whole story.  Check out the graphic below:
  • Celestron CGE Uncorrected - 52 arc seconds peak to peak
  • Celestron CGE w/PEC Enabled - 4 arc seconds peak to peak
  • AP900 Uncorrected - 1.4 arc seconds peak to peak
At 1.45" peak to peak, the AP900 has less native periodic error than the seeing conditions in most people's skies.
I'll do a more in depth review of it soon, but some of the features of the AP900 that I'm in love with:
  • Setting the mount to slew/guide past the meridian
  • Daytime polar alignment procedure is a huge time saver when it gets dark.
  • It has more weight capacity than I'll ever need in a field portable mount.
  • 1.5 arc seconds of periodic error out of the box.  I haven't even bothered to measure PE with PEC enabled.  The seeing is never good enough to make a meaningful measurement.  If I dare say it - the mount is seeing limited. 

The Telescope - Explore Scientific ED127CF 

Explore Scientific ED127CF refractor
127mm f/7.5 carbon fiber triplet
I'll just say it.  I don't love diffraction spikes in my images.  If you look up "Diffraction Spike Admirer" in the dictionary you will not find my photograph next to it.  I know some people dig them.  I'm not one of them.  It's one of the main reasons I even started looking for something beyond Hyperstar.  The fast images were awesome and I still think it's the best way for a complete newbie to learn the imaging ropes - but those cables in front of the corrector plate created some nasty spikes in the images.  I have an 80mm refractor at home that I've had for awhile and I was curious how it would perform so I put it on a mount and took some frames.  I instantly fell in love with the spikeless stars and the much better color saturation and started shopping for a refractor.  I chose the Explore Scientific ED127CF.  So far, I'm really happy with the scope.  I don't know if this is the "lifetime imaging" scope yet, but I do like it.

I'd love to talk about how great of a job it does on the planets and the crisp, contrasty, color-free views that it gives through the eyepiece but I can't.  I've looked through the telescope exactly once.  It has spent its entire life thus far as an imaging scope save for that first night out.  I immediately replaced the focuser on the scope with a 2.5" Moonlite focuser with stepper motors.  In conjunction with FocusMax I've been able to eliminate the chore of manual focusing from an imaging run.  It takes about 30 seconds for the laptop to focus the telescope and it does a better job than even the trusty bahtinov mask.  Look for a full review of the ED127CF and it's suitability as an astrophotography platform coming sometime in the future.  My only complaint thus far is that there is a bit of blue fringing around brighter stars when I take long exposures through my QHY8PRO one shot color camera.  A monochrome camera and filters would solve that problem though...

The Camera - SBIG ST-8300M
SBIG ST-8300M with FW8-8300
filter wheel.  The QHY5 and
50mm finder/guidescope is
also shown.

Say hello to the newest addition to the imaging rig.  I have made the transition to a mono camera and filters.  This addition is still so new that I haven't even had a proper first light yet - hopefully this weekend.  I recently bought an SBIG ST-8300m CCD camera and FW8-8300 filter wheel off of Astromart.  The deal also came with a full complement of Astrodon LRGB and 3nm narrowband filters. A test run in early July showed that the focuser didn't really have enough out-travel to reach focus with this setup.  I tried to cobble together a useable setup just to play around with it but the increased weight hanging off the end of the focuser created major flexure issues.  I ordered a focuser extension from Moonlite and a threaded adapter so that I have the most solid possible connection from camera to telescope.   Those parts are at home now but I haven't had a chance to assemble the rig and test it.  I've done some calculations and I expect that I'll be able to eliminate the need for a field flattener with this camera.  Experience will answer that for sure though.

I'm expecting big things from this camera and filter set.  With a full set of narrowband filters and our typical long stretches of excellent weather in Arizona I should be able to greatly increase the amount of time I have for imaging since they'll allow me to image from my moonlit, light polluted backyard.  The scope and camera combination provides me with an excellent image scale at 1.17"/pixel so I think this combination will be around for a long, long time.   

What's Missing?

I do believe that I'm really, really close to my perfect imaging rig here.  From a hardware standpoint I have the perfect mount.  My only complaint about the imaging scope is the violet color around the brightest of stars in a long exposure.  I expect that being able to focus each filter individually with my new mono camera will render that problem solved.  The camera is a nice size chip that's a proven performer and it's shooting through the best filters possible.  Much like my 15" Obsession, the imaging rig is setup in such a way that there's a lifetime of imaging there that I'll never be able to finish.  The only thing left that I would like to address is a better guiding solution.  I will probably add an off axis guider and a more sensitive guide camera some time in the near future.  At that point, there's nothing that I think I could improve from a hardware standpoint. 

I could possibly see an equipment rotator at some point in the future, but the system would have to demonstrate a real need for that piece of hardware.  Most people add the rotator to help them find suitable guide stars.  With the AP900 mount and a sensitive guide camera I should be able to take long enough guide exposures that I'll be able to find a guide star anywhere in the sky.  So I don't see it becoming a necessity - but experience is the best teacher.  I'll evaluate an equipment rotator once I've integrated the rest of this equipment.

Next time...I'll talk about the other half of the equation - software and the peripheral equipment.  Now that the hardware piece is (all but) completed, I'll turn my attention to the software integration and automation.  I'll share my thoughts and tips as I go.  Until's the last image shot with the QHY8PRO camera and the first dark sky image shot with the AP900 - NGC 5907.  I shot this from the incredibly dark skies of southern Utah over the weekend of May 20th, 2012.  Here's hoping the monsoon cooperates and I can feature a new image here next week.

NGC 5907 - 7h 45m exposure (31 x 900s)

Jun 28, 2012

Outreach Is The Cure For "Jaded".

The 15" and 20" Obsession(s)
were instrumental in Portal and
at the Grand Canyon.
Without question, the rate of the posts to this blog has....shall we say....occurred at a less than furious pace over the last six months.  All I can say in my own defense is that sometimes life gets in the way and if I have to choose between living life and writing about it, I'm always going to choose "living life".  It's not that I haven't been doing anything in that time - quite the contrary.  In the last 6 months I've been blessed enough to:
  • Work near full-time hours with two different clients.  It's not lost on me that while many people are still struggling for work, I have almost too much of it.  I try not to complain about the demand that it places on my everyday life. It's a blessing to be in a position that I've had to turn away work and I'm grateful for it.
  • Even with two(ish) jobs, I've been able to spend a good amount of time observing - trips to dark skies have abounded.
    • Multiple western Arizona trips including 5 days around the All Arizona Messier Marathon in March.
    • An invitation to observe near Portal, AZ and the Arizona Sky Village with some good friends in April.
    • A trip to southern Utah for the annular eclipse in May.
  • There have been many significant equipment changes which I'll detail some other time.
  • I've managed to do quite a bit of astrophotography too - some of it is even decent.
  • I've been blessed enough to do a lot of outreach work - and that's what I'll be covering today.
Leo Triplet shot at the All Arizona Messier Marathon.  10.5 hours total exposure with QHY8PRO and Explore Scientific ES127CF refractor. 

Give Something and Get Something

One of the ways that I try to conduct myself in daily life is to remember that I should always be giving something back to this life that has rewarded me so richly beyond what I deserve.  I fall short of this ideal much of the time, but when I manage to live up to it - I am inevitably the one who comes out on the winning end of the bargain.  When it comes to astronomy and outreach, this axiom has proven to be even more true.  When I talk about outreach, I'm talking about any sort of astronomical activity where I am not the intended primary beneficiary of the activity.  This can include everything from writing this blog to helping a club member out with some image processing tips to settting up a telescope and showing the universe to a complete novice.  It has yet to fail that when the motive is selfless, the reward is always beyond anything I could have imagined.  This is the beauty of outreach.

The kind of outreach I'm talking about here is the more common definition - setting up a telescope and showing the universe to less experienced eyes.  I've always been keen on outreach and some years ago, back in the early 2000's I did a good amount of it locally.  I'd like to say that work, life and family made it difficult to continue the outreach work - but if I'm being honest, the truth is that selfishness is what made it difficult.  I focused more on things that had a direct payoff for me...and in the end found that it was a far less fulfilling way to proceed through life.  One of the things that I've found to be true, at least in my case, is that we tend to become jaded.  After I've looked at Saturn a hundred times it becomes 'just Saturn' to me.  Let me show Saturn for the first time to a child who's never looked through a telescope before and it reminds me why I fell in love with the night sky in the first place.  Outreach is the cure for jaded.  This time around in my haphazard and checkered amateur astronomy career, a number of things have come together at just the right time and in just the right sequence to renew my love for this amazing hobby obsession. 

While the initial intention was honorable, my outreach activities weren't entirely altruistic starting out.  Last November I fulfilled a dream of purchasing a travel trailer for camping and amateur astronomy.  It has become affectionately known as "The Command Center" amongst my astronomy friends.  When January 1st, 2012 rolled around I was one of the first in line to volunteer to setup a telescope for this year's Grand Canyon Star Party - North Rim.  While I was excited about the prospects of the outreach and sharing the night sky with visitors to one of the most amazing places in the world, I was equally excited about being given a campsite for the command center in the North Rim Campground for eight nights.  Getting a campsite for one night is difficult enough, but getting one for eight nights is next to impossible.  I began to daydream about all the daytime wanderings that would now be possible.  In the end the outreach was the highlight but more on that later. 

Mount Lemmon and Messier

My June 2012 observing site

In early March, as I was preparing to haul The Command Center out for the All Arizona Messier Marathon, I was contacted by one of my astronomy friends to see if I had any interest in doing some outreach at the Mt. Lemmon SkyCenter.  I quickly answered "Duh!!"  Of course I would!  On a couple of occasions since then I've made the 3 hour trek to the 9100 foot summit of Mt. Lemmon and assisted with their SkyNights program.  Besides getting the thrill of sharing some people's first experience with the night sky through a telescope, it's always a joy to share the sky with people who are genuinely interested in the knowledge that you have to share.  It's that exchange that makes outreach so much fun.  Being able to view the universe through a 32" Ritchey-Chretien from the top of a 9000' Sky Island doesn't hurt either.  There is interest on both parts (mine and the SkyCenter) to make that a more permanent arrangement but as of yet that hasn't completely materialized.  If you ever make time to get down to Tucson, Arizona a trip to the SkyCenter and a trip to the Steward Observatory Mirror Lab should be on your required list of things to do.  You can't appreciate the size of an 8.4 meter mirror until you're standing next to it.

In late March, I did indeed haul out The Command Center for the All Arizona Messier Marathon and it was a great time.  As I used the five day trip entirely for astrophotography, I had a lot of time to walk the observing field and catch up with friends old and new alike.  I spent a bit of time with some students from ASU and a young woman out for her first star party ever and did a little outreach and promotion of astronomy in general.  Highlight of the trip though was the opportunity to spend a significant amount of time with a young guy who's fanatical about astronomy outreach.  Spend five minutes in a room with Kevin Legore of Focus On Astronomy and you'll be ready to run out and point a telescope skyward to find all the stuff that William Herschel missed the first time around.  His efforts are tireless and he's regularly hosting events in an effort to share the night sky with new eyes whenever he can.  It was a sad day for Arizona astronomy when he moved to southern California soon after the star party.  He continues his outreach work in So-Cal and occasionally makes it back to Arizona as well.  If you get a chance to attend or support one of his events I highly encourage you to do so.  Kevin is also a longtime fixture at the South Rim edition of the Grand Canyon Star Party.  In his work life he's a purveyor of fine astronomy instruments. If you just want to talk about astronomy equipment, he's also a walking encyclopedia of astro-gear knowledge - so stop in at Woodland Hills Telescope and chat him up if you're in the area.  

Grand Canyon Star Party

It took six months to get here, but finally it was time to make the trek northward for the Grand Canyon Star Party - North Rim.  The Tucson Astronomy Club typically handles the festivities at the much larger and more crowded South Rim.  A few years ago the Saguaro Astronomy Club assumed the duties of providing telescopes and outreach at the North Rim.  The two star parties are only 10 miles apart if you're a bird, but they're two entirely different worlds.  They're both an awesome time....just different.  We arrived early on Saturday and claimed our campsite.  After setting up camp we drove down to the Grand Canyon Lodge to setup telescopes on the veranda - overlooking the Grand Canyon.  At the South Rim there are more scopes and it's a bigger affair.  At the North Rim, there's only about a dozen scopes but it's such an intimate setting that you can trip and spill a drink right into the canyon.  We set up the heavy artillery near the door leading into the sun room - the highest traffic area in the lodge.  I prepared my 15" Obsession right next to the ramp that empties onto the veranda and my friend Chris setup his 20" Obsession behind it, overlooking the canyon and commanding the attention of every person within sight of it. 

When the sun had set and Saturn appeared, the madness began with a quickness.  Before twilight had even really set in, the line at my telescope was twenty people deep all waiting for a look at Saturn.  It was awesome!  People were astounded at the views and what could be seen through a telescope.  It gave a great opportunity to expose people to amateur astronomy in one of the greatest settings in the world.  As night fell it got dark down in the canyon - as in pitch black.  But looking skyward, it was a dark grey with what can only be described as a stoopid amount of starlight.   The Milky Way was obnoxiously bright and particulate matter in the atmosphere - presumably from the New Mexico wildfires - completely blotted out any indication that Flagstaff and Phoenix were to the south.  This pattern would repeat itself for all eight nights.  When you get eight straight nights at 8200' elevation with 10% humidity and temperatures in the mid 50's and absolutely no light pollution the astronomy Gods have smiled upon you.

I got to share the universe with so many excited people and it renewed everything about amateur astronomy for me in just that first night.  In most excellent fashion I got to repeat it for eight nights.  I've rediscovered my love of visual observing and got to put a lot of smiles on people's faces in the process.  I figure that I met somewhere around 1500 people in those eight nights and counted at least 24 countries represented.  Over and over I heard things like:
  • Is that fake? 
  • Is that real? 
  • It looks like a picture.
  • I've never seen anything like that in my life.
  • I had no idea that you could see those things with your own eye.

Over and over people were amazed and happy that we had come to share the night sky with them.  If I heard thank you once, I heard it a thousand times that week.  On the first and second nights we were priveleged to spend time with an 8 year old named Lauren.  She was so excited the second night that she was jumping up and down while she stood in line.  She soaked up every object that was shown to her and stayed excited for more.  That sort of enthusiasm is infectious.  Over the course of the week I had at least a dozen people who were pretty advanced in their years - seniors if you will - who commented that they'd never seen anything so wonderful in their life and that everyone should see this stuff at least once. 

On Wednesday night I had the privilege of being the speaker for the evening and presented a topic on the distance scale of the universe.  It was well received and one little girl was so enthralled that she hung around afterward to talk some more with me about it and spent much of the evening at the telescope with me asking questions and reconciling her views in the eyepiece with the information from my presentation.  It was just awesome stuff. 

What was in it for me?  Depends on how you measure it.  If you measure it in the things of this world - it was a losing proposition.  I paid money out of my own pocket to haul a travel trailer 300 miles up 7000 feet of elevation gain and gave up a week of my life showing the universe to the public for a few hours each night.  I was reimbursed for none of it.  And if that's the way that you're missing out on the whole thing.  Because I got so much out of it that I can't wait to waste all that time and money again next year - even if it costs twice as much. I got to:
  • watch people's minds expand at the sight of a universe they never knew was there.
  • see an old woman cry at the sight of Saturn's rings.
  • stoke the imaginations of children who were curious about the sky.
  • watch the sunset in the Grand Canyon eight straight nights for free.
  • laugh, and laugh, and laugh with friends from my astronomy club.
  • spend 9 days with absolutely no technology between me, my family and our surroundings.
  • hike in the Grand Canyon and explore Northern Arizona - for free.
I can't wait now for the next new moon myself so I can get back out and image and observe our universe.  It's like being a newcomer to the hobby all over again, you can't wait to see it all.  And I can't wait for next year so that I can do it all again.  Outreach reminds me of what's important in this life - it's the giving and sharing.  It's being selflessly available to share what you have to offer whenever the opportunity presents itself.  My tendency in life is to be harsh and rigid and it never pays off well.  The outreach opportunities - especially Mt. Lemmon and Grand Canyon Star Party - are the examples that remind me of the true rewards in this world.  If I've learned one thing in this life and this hobby it's that you should give without expecting anything in return wherever possible.  You'll inevitably be rewarded beyond anything you could have imagined.