Fine Focus

For any astro-imager, focus is always a primary concern. When doing deep sky it has to be spot on to get those tack sharp stars that we love to see. Fortunately for DSO imagers, there are aids such as a Bathinov mask that can help ensure you are on the mark.

Bahtinov Mask

 In planetary imaging it is a little more challenging. We also need to be in perfect focus to capture the subtle details, but a Bathinov mask isn't going to work on a non-point light source. Trying to move the scope to a bright star to focus first before centering the planet also seems to fall short. What one is left with is manually fiddling with the focus knob while watching a feature of the planet to get it as sharp as possible. For example, a Jovian moon or the Cassini division are often good targets to pay attention to in this effort.

Unfortunately the planetary imager is confronted with another problem: the high magnification utilized to get the planet's disk to a suitable size. This means that the slightest touch causes the planet to wildly dance in (and sometime exit from) the field. The result is an iterative set of focus-recenter-evaluate attempts until you feel it is as good as you can get (or your patience is gone and you settle for "close enough"). When rebuilding the OTA for my 10" Cyrus¹ Newtonian I even invested in a nice JMI focuser with a feather touch micro-focuser, but it still didn't solve the fallout of a human hand touching the scope.

I finally came to accept that investing in a motorized focuser was going to be necessary to solve the problem. Based on the positive experience Dale Ghent had with MoonLite focusers for HALO, I opted to order from them. It takes a bit of time to go through all the various options but I eventually balanced my desire for bells & whistles with my budget to get a Crayford 2" focuser with their universal adapter and stepper motor for about $700. To my surprise and delight they had the unit to me within about a week.

Next came replacing the existing JMI with this snazzy unit. If you look at their universal adapter, it is "a plate with multiple many different 4 bolt hole patterns for Newts over the years, Meade, GSO, Orion, Celestron, etc." 

 

However, none of them aligned with the existing holes I had placed into the tube when installing the JMI focuser. So it became a tedious process of securing the plate with a couple of openings that did align and then trying to accurately measure where the new hole had to be drilled to accommodate where the opening was on the plate. After a couple of hours the plate was finally secured and motorized focuser attached. 

 

Installed MoonLite Focuser

As you can see from the picture above, this is a substantial unit. It occurred to me that this would probably alter the scope's balance once I added in the Barlow, camera, and possibly an Atmospheric Dispersion Corrector (ADC). In the past the scope had always been a little "rear heavy" when imaging, requiring placement of a magnetic weight along a shelf bracket that runs along the front half of the tube. I opted to install a similar bracket along the back half of the scope, and indeed it was needed to achieve balance when I did a dry run.

A couple weeks later with Jupiter and Saturn getting a reasonable (if not great) altitude in the pre-dawn skies, I gave the MoonLite unit a test run. I did not purchase a separate hand controller to operate the focuser but instead attached it to the laptop using the provided USB cable. The unit also has to be powered - so yet another cord dangling from the focuser that I tried to tuck alongside the scope to avoid any tension or vibration it might cause.

The interface is pretty intuitive, allowing you to move in or out by orders of magnitude. Once Saturn was centered it was easy to display the planet in the video capture software and have the MoonLite Single Focuser app on top so that I could watch the planet as I commanded the focuser to adjust its position. During the process there was minimal movement of the planet and no risk of knocking it out of the field. I ended up getting what I felt was as good a focus as I could achieve and was happy with the result after I processed the video captures the next day (below). 

While the swapping out of the original JMI for the MoonLite ended up being a little challenging in the installation stage, I'm very happy (and blessed) that I could do it because the results are what I was looking for - a far less painful and far more accurate focusing experience. Like so many other hobbies, amateur astronomy (especially when coupled with photography) is an investment. It seems to be a continuous process of identifying what might improve our ability to see or photograph the heavens and then budgeting to make that next upgrade.
 

¹ I call it the "Cyrus" telescope because the optics were made by Charles Cyrus, a friend and excellent ATM from back in my days with the Baltimore Astronomical Society. After Charlie's passing his instrument made its way to me and I have enjoyed it for a couple of decades now, most recently redoing the OTA that houses the mirror.

Second First Light

Compared to half a century ago we pretty much live in an astronomical COTS time. The vast majority of amateurs peer through equipment that is massed produced. Attending a BAS star party back in the 70s and 80s, one would find a fair number of the telescopes were fashioned by their owner. They ground the mirrors and constructed the mounts, displaying a range of frugality and craftsmanship in their implementation. Many clearly had taken "shop" as part of their secondary education and were comfortable turning out custom parts for their scopes. 

One of those individuals was Charlie Cyrus who built a 10" Dobsonian. I will always remember the first time I peered through the instrument at M13 - I was blown away at how well it resolved the stars compared to my 6" telescope. When looking at the planets it always provided crisp views that spoke of the hours he had poured into sculpting the glass to his standards. Charlie was the epitome of an ATM.

When Charlie passed his good friend and fellow BAS member Dr. Richard Pembroke became the steward of his telescope. Richard was a passionate, respected amateur astronomer and well connected to the community of observers. As he contemplated downsizing in retirement he asked if I was interested in having Charlie's telescope. I immediately said yes even as I pondered how I could explain to my wife that I had another telescope in the garage. 

For about 15 years I used the Cyrus scope as often as I could. Its additional aperture allowed me to track down multiple additional Herschel 400 objects and pick out more details among Jupiter's clouds and Mars' surface. It accompanied me to many Stellafane visits and Tuckahoe star parties, creating memories along the way. But time and use took its toll, and eventually the wooden Dobsonian mount became too feeble to properly support the optical tube assembly (OTA). I could almost hear Charlie saying, "OK Jim, it's your turn now to use some ATM skills to restore it!" 

And so I set off on what would turn out to be a multi-year endeavor to give Charlie's scope continued life observing the heavens. I elected to replace the Parks tube that housed the mirrors since the focuser (which Charlie had made) was no longer usable with too much slop. Lacking machine shop skills, and no friends with that talent, I calculated that a sturdy "Sonotube" would be best since it was a material I could work with. I ordered a long, sturdy tube - thicker than a Sonotube to ensure support - and cut it to size. This was like pulling the thread that unzips the seam, because now the machined mirror cell had to be adapted to the new tube, or a new one made. It seemed that I would clear one hurdle and then have yet another technical challenge to address. But finally the new OTA emerged under my hands. 

One of my primary objectives was to have the scope on a mount where tracking was feasible. My grand scheme was a Dobsonian tube cradle that could have a mounting plate affixed to it, permitting the OTA to move from Dobsonian rocker box to my Orion GEM, offering the best of both worlds. I made several attempts at it before finally facing the fact that it was not going to work - the Cyrus OTA was just too heavy. 

Growing tired of having the OTA but no mount, I elected to contract the task of creating a Dob mount. I coordinated with a shop out in California about a year ago and ordered one of their products, hoping that I could add a Losmandy mounting plate to the tube cradle to permit me to attach it to my sturdier CGX-L GEM that I had acquired. I had hoped to have it by the Mars opposition last October, but that deadline came and went. Maybe by the Grand Conjunction in December, but that, too, came and went. Finally I received it in April and assembled the new Dob for the Cyrus scope.

The mount seemed adequate and I believed it would work out as I placed the OTA into its cradle. One issue I noticed quickly was that even though I had added additional felt liner, the tube would still slip down under its own weight. But that felt like a problem that could be fixed. With the Moon almost full it served as a convenient target to verify if the optical train was properly configured. I found that the mirror needed to be set back down the tube in order to achieve focus, but again, a task that was very doable. 

Almost there! Or so I thought. The next free weekend I set about repositioning the mirror and adding additional felt when I noticed that the laminate on one of the wooden altitude bearings was separating. Indeed, the entire thing was coming loose and breaking. I couldn't believe it and contacted the vendor. Long story short, there would be no resolution from this person, and given the delays in receiving it I was not about to ship it back and have another year pass waiting and hoping for this individual to make it right. One benefit of my heart attack has been making it clear to me that every day counts.

Laminate Separation

I decided to take off the Friday before the July 4th holiday and dedicate that 4 day weekend to making a tube cradle with an attached Losmandy plate that could support the OTA on the sturdier mount I had purchased - no more excuses! In some regards it reminded me of software development in terms of the life cycle - design, create, test, remediate defects you uncover during testing and try again. Finally, in the pre-dawn hours of July 5th, I got a true "first light" for my Cyrus scope restoration by imaging Jupiter for an hour. The detail it provided, along with the exciting prospect of having this wonderful instrument back, made it all worth while!

 

And now the refinement process has to happen, steps to take to make the telescope easier to use (because a telescope that requires a lot of effort to set up for a session does not see as much starlight). Inspired by some photos of HAL member Victor Sanchez's setup, I used last weekend to craft a "dolly" so that the entire rig can be rolled in and out of the garage. Next up will be adding a dovetail to attach a finder scope and hopefully a paint job to make it look a little more polished. The biggest lesson in this journey has been a better appreciation and respect for the talent, effort, and ingenuity that an ATM puts forth into their telescope - truly a labor of love from which I have benefited greatly. Thank you Charlie for leaving behind such a gift - I'm proud to be its steward and hope I'll pass it to another generation of stargazers one day!

Got to GoTo?

So if I yelled "Tastes Great!...Less Filling!" - what comes to mind? If you grew up in the 80's (and maybe even if you didn't) you'll recognize that as the catch phrase for Miller Light beer, ranked as one of the most successful marketing campaigns of that era. It epitomizes the situation of two camps staking out and digging in around their assessment of a product. 

Amateur astronomy has certainly seen its share of hotly debated issues. For many years as digital photography came to the marketplace we sparred over whether it would (or even could) replace film for capturing quality images of deep sky targets. That one seems to be settled. Then there is the occasional discussion of whether digital media is better than a hard copy. I'll confess that I still like a book/magazine/newspaper in its printed format over the digital. There is something thoroughly enjoyable about thumbing through a volume of Burnham's Celestial Handbook, perusing a constellation that will be available for viewing that night. But as the digital revolution has unfolded we also enjoy the portability and accessibility of online content.

One enduring topic of debate is most certainly the merits of using a computerized mount with "GoTo" capability when you are out under the stars. For the better part of 50 years I've been a star hopping guy, planning my trip to that evening's targets with a little research and printed maps to outline the approach to be used. Sometimes half the fun was that research and planning to capture the target, and then successfully bagging that faint fuzzy provided a sense of achievement and affirmation of my skills. Undoubtedly it gave me a foundation of the heavens and the ability to bring a variety of celestial showpieces into the eyepiece on any given evening without any aids.

As I've noted in prior postings, last August I invested in a Celestron CGX-L mount. My main motivation was the hope of better tracking for some photography and the ability for it to bear a larger OTA than my old Orion Atlas mount could handle. One of the features of the mount is, of course, "GoTo" functionality. I will confess that it's very seductive. 

My current project has been revisiting the AL Urban List objects using my 80mm Vixen refractor. The open clusters in Monoceros are particularly challenging since there are very few stellar guideposts available amid Bortle 8 skies to serve as a foothold when setting out on the star hop. So when taking the scope out this past week on a cold and clear winter evening my prep was primarily generating a list of objects along with a very brief description. Once aligned the mount did a fantastic job of centering the targets, leaving me time to inspect and sketch each of them. Where I might have bagged one, possibly two, of these clusters by star hopping I was instead treated to a very pleasant and productive session before my toes became too numb.

I would submit that there are strong parallels between "GoTo" functionality and our reliance on satellite navigation when driving to an unknown destination. It's said that many under the age of 25 simply have no skills for picking up a map and using it to see where they are and how to get where they need to go. While I do make use of apps like Wase from my phone, especially in heavy traffic or when driving solo to someplace I've not been to before, I often will not bother if the route is one I'm reasonably familiar with. As a teenager delivering prescriptions for my dad's pharmacy in Baltimore I acquired a pretty good sense of the main arteries and thoroughfares around here, so it seems natural to eschew the voice giving me commands and go my own way. It may be that getting your terrestrial bearings and navigating from a map is going to be relegated to a sort of black art practiced by old codgers like myself. I am still amazed sometimes how the person behind the counter is totally reliant on the cash register to determine the change due from a $7.23 meal when I hand them a $10 bill. Thanks dad, having me work at the pharmacy taught me that one as well.

But back to our task of celestial navigation. There is another value to star hopping beyond getting a grasp of the sky. As noted by Bob Prokop in a recent thread on the HAL group, you have no idea what little gems you are gliding past when in autopilot mode. I specifically recall stumbling across the beautiful double star WZ Cassiopeia one night on my way to NGC 7790. I likely spent more time looking at that then the intended target.

Perhaps the appropriate balance for a new telescope owner with the technology is to challenge themselves to star hop to the brighter Messier and Herschel 400 objects. It is not that hard and gives you the satisfaction of bagging the target based on your skills, not your equipment's. Take your time when sweeping the area for your quarry and soak in the neighborhood, letting your eye search for colors and your brain form interesting patterns among the field of stars. Simply because it does not get called out on an atlas doesn't mean it's unworthy of a few moments of admiration. But then when the need arises to find (or confirm) the end point of a challenging star hop, you'll find that computer assistance to be a real boon. Yes, computerized mounts can be highly efficient, but is that really where the enjoyment lies in amateur astronomy for you?

Circumventing an Obstacle

Roughly 18 months ago I pulled the trigger on a PoleMaster for my Atlas mount. If you're unfamiliar with the instrument, it's a digital camera that attaches to the front of your mount so that it is aligned with the RA axis. Then with accompanying software you can perfect your alignment to achieve the best possible tracking from your system. While there are other gadgets and techniques that are useful to get a good polar alignment I found this system to be a solid, workable approach for me.

My Orion Atlas mount has been a good work horse for well over two decades in my observing. It was my first "real" mount that could adequately track the sky, opening up not only a more pleasant observing experience but also planetary "lucky imaging" with my 6" reflector and then deep space targets when I acquired my Vixen 80mm scope. It was portable enough to fit in the back of my Rogue, traveling with me to nearby Alpha Ridge or out to Wyoming as part of my Great American Eclipse road trip. The power source was never a worry - a simple battery pack of 4 D cell batteries that seemed to last forever (and easily acquired at the corner drug store if they were to give out.)

The "Leo Triplet" taken with Vixen 80mm & Atlas mount

But even with the PoleMaster, the tracking was not accurate enough to allow for exposures beyond 20 seconds, causing me to resort to a very large number of short subs in order to arrive at a respectable image. Another shortcoming is the weight bearing capacity of the Atlas - there is no way it would be able to support my 10" reflector that I am hoping to complete refurbishing this year. After taking several months to research various mounts on the market that would work within my budget I finally took the plunge and invested in a Celestron CGX-L mount which arrived in September.

In the almost six months since acquiring the CGX-L I have had it out perhaps a dozen times. The first couple were to simply get acquainted with the unit (I am glad no one witnessed my first night when it took me over 40 minutes to realize that there was an "on" switch that had to be toggled - I had just assumed that when I plugged in the battery that it was ready to go like my Atlas!) With it powered up I followed the instructions on how to perform a two-star alignment with an optional 4 additional stars. Once that was done the computer assisted tracking worked surprisingly well. And, truth be told, that "goto" functionality really makes me feel like I'm cheating after a lifetime of star hoping. 

Polar alignment, however, is back to roughly eyeballing the RA axis in the direction of Polaris. According to the manual one also can precisely align to NCP following the star alignment process by entering the "align mount" routine. In theory, you center a star in your eyepiece and then the computer moves the scope to where the star should be if you were properly centered on the pole. Your task is then to use the mount's azimuth and altitude controls to center the star and thereby refine your polar alignment.

I will confess that I have yet to try this routine. I could not help but want to use the PoleMaster which worked so well. But, alas, the design of the CGX-L has a handle bar directly in front of the RA axis of the mount. It seemed that I would not be able to have my cake and eat it too - those handles are indispensable for positioning the heavy mount head onto its tripod. 

Thinking I was likely not the first CGX-L owner to feel frustrated by this obstacle I spent time searching online for solutions that others may have come up with to use their PoleMaster. And, as so often happens, the Internet did not disappoint. On Cloudy Nights there was a reference to a guy who designed a literal workaround; a 3-D printed component that attaches to the face plate with a detachable U shaped bracket to hold the PoleMaster camera. Genius! Brilliant! And the best part was that he was selling them on eBay with about a week's turn around time. The credit card came out within sixty seconds of watching the video demo of it. 

Last month I finally got the chance to install the adapter and try it out. The Celestron mounting plate was readily removed and replaced by the custom printed plate. The U bracket's holes aligned beautifully with the PoleMaster camera so that I could transfer it from the Atlas adapter to the 3-D one. And to make attaching the U bracket to the face plate foolproof the creator provided two guide pins that snap into place thanks to a couple of strong molybdenum magnets. (It brought back memories of my dentistry days, fabricating dentures that seated and held fast with the use of such magnets - but that's a story for a different blog 😉). The video below shows the component and how easy it is to use. Problem solved!

I have a feeling that this recent experience reflects yet another paradigm shift for amateur astronomy. While 3-D technology has been around for a while it is clearly becoming more mainstream and allowing imaginative engineers to bring their designs to rapid prototype and market. We recently had a discussion on HAL's email group regarding this very topic, and several folks chimed in about how they were using parts/accessories created in this fashion. In the "good old days" this was the realm of the machinist who had access to a shop where equipment could turn out custom parts. What we may lose in the durability of a machined part is going to be offset by the accessibility to many more people with innovative approaches to solving problems and creating new tools for our astronomical community. I can hardly wait to see what comes next!

Celestial Oenology

It's the holiday season and, like every year, thousands of people will be convinced that they want to take up astronomy as a hobby. Even before Thanksgiving this year I've had two people reach out to me for advice on what telescope they should buy for a loved one (or perhaps in truth the scope is for themselves as well as the loved one). Facebook teems with posts asking the same question. Unfortunately there is no easy answer to the question of "what's the best starter telescope?" because it is a nuanced question with a variety considerations. 

Suppose that instead of exploring the universe you were taken by the idea of exploring the world of wines. Perhaps you had a friend who introduced you to a couple of nice wines at a dinner party. They skillfully chose the wine and paired it with some good food to create a delightful experience.

The Party Introduction

Or maybe it is those posts on social media or articles in a magazine you thumbed through in the doctor's waiting room. They tease at this world of tasting & enjoying wine that convinces you that you want to explore this hobby. 

Whatever the trigger, you are sure this is worth pursuing and you want to purchase a corkscrew to enable you to enter this realm. But which one is best? An inexpensive and rudimentary one may only be good if your are skillful enough to wield it. An expensive one with bells and whistles may work for any bottle but likely requires you to read the manual thoroughly to use it properly, spending as much time opening the bottle as consuming it. A simple but efficient opener should allow you to master its use quickly and serve to open many bottles of wine.

With your new tool to open the oenophilic world your next step is to target some wines, so off to the liquor store. The array of choices can lead to analysis paralysis. Red or white? Fruity or dry? Each category of wine seems to have its own characteristics and proponents. You might ask your friends who already enjoy wine what their favorites are and try sampling some for yourself. Or perhaps you follow the recommendations in a magazine or good book to start you on your exploration. As you sample the varieties you find you're drawn to some more than others and become passionate about locating ever more examples of your favorite. You also might find that keeping a log with notes about the wines you've tried helps improve your appreciation of them.

After some time you become aware of accessories that can possibly deepen your enjoyment of your favorite varieties. You open up your wallet and start to add to your armamentarium of wine tools. Some prove to be useful for any bottle you select, while others have more specialized application. 

So let's distill what our theoretical journey into Oenology can offer the budding amateur astronomer:

1.  When picking a telescope you should probably avoid inexpensive models that will frustrate you and likewise expensive models that will likely baffle you. Somewhere between $300 to $1000 should net you a quality starter telescope that can give years of pleasure, even after you upgrade.
   
   
2. Figuring out what to view is challenging so consider asking other amateurs what they enjoy, or pick up a copy of a book that is geared towards initial exploring of the universe. Just like wine is an "acquired taste" with many glasses needed before you can discern those subtle flavors of a vintage, examining faint fuzzies or planetary features is an acquired skill. The more you observe them and read about them the more subtle details you'll uncover and savor.
   
   
3. Just as your wallet will dictate whether you can afford to taste the more subtle and exotic wines, your budget will also influence your ability to experience the heavens. If you are smitten by seeing features of Jupiter and Mars then sharp optics, tracking mount, and a video camera are in order. If you yearn to see the spiral arms in M51 then a large Dobsonian will fill the bill. But they will mean a financial commitment.
   
   
4. Just as oenophiles gather at wine tastings to share sips and opinions, amateur astronomers benefit greatly from joining a club and getting out under the stars together where they can share views.
   
   
5. Accessories can make your hobby more enjoyable and enhance what you taste/see. Do your research before making a purchase by reading reviews online or checking with club members who already use the item, but gadgets are part of the fun.

Go ahead and take the plunge into the world of amateur astronomy - it can provide you years of enjoyment and new friends that share your enthusiasm.