Sunday, January 03, 2016

 

Goodbye Betsy, Hello Hermione...


2015 was a year of changes for me. Not the least of which is one you may be aware of if you are a Facebook friend of mine:  I sold Old Betsy; she is gone. Yes, the telescope that’s been at my side as my faithful companion for the last twenty-one years has gone to live with new owners, a young local couple. Never thought that would happen, did you? Neither did I, neither did I.

I won’t wax nostalgic about all the fun Bets and I had and all the star parties we went to over the last two decades. No point in that. It was time. Far worse than letting go of my 12-inch Dobsonian would have been letting her sit out in my shop and rot. I was simply not using her, you see. What finally impelled me to say goodbye was realizing she had not had any significant time under the stars since November 2014.  I decided I’d be happier with the telescope in a new home where she’d be loved and used.

I didn’t give Betsy away, but I sold her for a very reasonable price. Nevertheless, I found myself with sufficient cash in hand to finance a new telescope. While, yes, I am reducing the head-count here—I’ve also gotten rid of two C8s so far—that didn’t mean I wouldn’t consider adding a new one. It would just have to be a telescope that fit in with my current interests, prime-focus DSLR imaging and casual visual observing. Most of all, it would have to be a scope I would actually use.

It surprises some people to learn I am a refractor-phile. Yes, I’ve long been known as “Mr. SCT,” in part because I have written two books and more than a few magazine articles about Schmidt Cassegrains. However, over the last decade or so refractors have easily become my second most used and loved telescope, and today are not far behind SCTs in my telescope pantheon—if they are behind SCTs at all.

Refractors are just so easy, especially for astrophotography. Sharp images, little cool-down, no fussing with mirror flop or focus shift, moderate focal length. There is no doubt they produce beautiful visual images, too. I won’t bore you with a paen to the TINY STARS a good refractor can present, even at high power. I’ll just say that for me (and maybe for you, too, if you reach way down into your soul) there is just something special about lens scopes.

So, yes, I’d come to love refractors, and had some good ones for both imaging and for visual use, but what I didn’t have was a big one, which in refractor speak is a 5 or 6-inch. While my 3 and 4-inchers can do well for imaging, there’s no doubt a 5 or 6 will pull in more stars, and that for visual a 5-inch refractor is where things start getting interesting.

So which would it be? A 5-inch or a 6-inch? I soon decided against a 6-inch. If possible, I wanted to stay within the modest budget provided by the sale of Betsy. Getting an ED/APO sixer would have meant tripling that at least. Sure, I could have gone “achromat,” but the major reason for doing so would have been bragging rights, being able to say I had a 6-inch refractor.

The ground truth is that a good ED 5-inch can beat one of today’s affordable achromats at most things. Certainly, imaging and image processing would be complicated by the chromatic aberration inherent in fast (f/6 - f/8) achromats. Also, while a 6-inch would have been OK on my CGEM mount, I thought a 5-inch would be better. And I thought a 5-inch would also be more than usable, for visual at least, on my Celestron VX GEM.

And so the hunt for a 5-inch APO began…

I ruled out the Astro-Physics and Takahashi refractors from the get-go. Beautiful scopes and wonderful performers, sure, but costing so much more than what my budget, even stretched to the breaking point, would allow as to not even be funny. I was also uncertain I’d live long enough to receive an AP130 given the notorious waiting times for that fine instrument.

I know better than to scrimp when it comes to quality, however. I wouldn’t be penny wise and pound foolish. I gave due consideration to the next tier down, the 5-inch aperture range telescopes from TEC and Stellarvue and William Optics. I was especially attracted to the WO FLT-132 and the StellarVue 130. Both would bust my poor budget, but not nearly to the extent of an AP or Tak, and both were beautiful and highly regarded. What if there were a way I could get a 5-inch more attuned to my modest means without sacrificing optical quality, though?

Perhaps the biggest recent change in the refractor scene, an almost revolutionary change, has been the appearance of reasonably priced 5-inch ED/APO scopes in the 1500 – 2000-dollar range. Yes, you read that right, 2K or less. The two leaders in this arena so far have been Explore Scientific with its JOC produced scopes and SkyWatcher with its Synta-made refractors. I began researching two candidates, the Explore Scientific ES 127ED, and the SkyWatcher Pro ED 120.

I eliminated one scope immediately. Explore sells their 5-inch refractor in two variants. The "Essentials" version is furnished with a white aluminum tube and looks a lot like the ES achromats. The other, the premium 127, uses the same optics, an ED triplet, but in an attractive carbon fiber OTA. I didn’t think carbon fiber was a necessity given our usually balmy wintertime temps, so despite its good looks I passed on the carbon fiber ES.

The other contender was the SkyWatcher Pro ED 120. At first, I was a little hesitant to give up 7mm and live with “almost” 5-inches, but much as I liked the ES scopes, I gradually began to turn more to the SkyWatcher. While the objective on the SW is a doublet rather than a triplet, one of its elements is of FPL-53, synthetic fluorite if you will, and all the reports I read said the telescope’s color correction was every bit as good as the ES’ triplet, and maybe even slightly better.

The more I researched, the more I came to believe the SkyWatcher was the scope for me. Not only were the optics (reputedly designed by a Takahashi refugee) admired, the scope came with considerable lagniappe compared to the ES. In addition to the OTA, the SkyWatcher package included a 50mm RACI finder, a pair of eyepieces, a 2-inch star diagonal, and, most of all, an aluminum case. The current ES packages seem to lack all these things.

There were plenty of finders and eyepieces and diagonals around here, but the case was a pretty big deal. For a refractor to live up to its ultra-portable reputation, it really needs a good case to protect it and keep it and its components organized, and it would be nice not to have to shell out more bucks for one.

In all my reading and asking around about the SkyWatcher, I only uncovered one thing about the scope that was routinely criticized, the focuser. While most users rated the standard Synta Crayford as useable, there was no pretending, I gathered, that it was within a country mile of a Moonlite or Feathertouch. That was OK. Given the amazing price of the Pro ED 120, which was on sale at Christmas for freaking $1399.00, I figured I’d be able to replace the focuser with a Moonlite if I had to. So the SkyWatcher it was. I grudgingly gave up my credit card number and spent a week in anxious waiting for the new baby to arrive.

The Unboxing…

The coming of the new scope was actually rather anticlimactic as such things sometimes go. I was surprised at how heavy the box was and half dragged-half carried it into the sun-room where I do my telescope unboxing. I was slightly disturbed at the sizable gouge in the box, but that turned out just to be in the outer carton and the telescope’s aluminum case was completely unharmed. Kudos to SkyWatcher for doing a good job packaging wise. Anyhoo, with the new kid out of her box, my impressions were, in no particular order:

·        Nice and light for a refractor in this aperture range. At just over 11 pounds and with a “reasonable” length of tube at its f/7.5 focal ratio, the 120 was, I thought, going to be very good on my prole VX and CGEM mounts.

·        A pretty thing. I must admit I prefer all-white telescopes, but the 120’s black/bronzish metal-flake tube and white trim is striking.

·       The focuser seemed OK. Stiffer than I like, perhaps, but smooth. And the smooth and easy fine-focus control made up for any stiffness in the course focus. One big plus was the wide focus range. I found I could rack this Crayford out far enough that I would not need an additional extension tube to bring a camera to focus with a standard prime focus adapter or field flattener.

·        Beautiful objective lens with faint greenish looking coatings. Very good coatings, I thought, since the objective seemed to disappear when I looked down the tube, even in fairly bright light.

·        Decent accessories. The included 2-inch diagonal looked good. Metal and hefty. The two 60-degree AFOV eyepieces, a 20mm and a 5mm? OK, and at least a modest upgrade compared to the “free” Plössls you usually get with telescopes these days. The 50mm finder was also fine, if not any different from what we are accustomed to seeing from China these days. The case was excellent, I thought. Not strong enough to ship the scope in, no, but more than good enough for hauling the 120 to star parties in the back of my 4Runner.

·        Tube rings and (Vixen format) dovetail? I’d have preferred the better rings furnished with SkyWatcher’s up-market triplet APOs, the Espirits. The 120’s tube rings are standard Synta. I believed they would do the job, but they were certainly not as pretty as those that come with the more expensive scopes. On the other hand, the dovetail was nicer than what I usually see on Syntas. Given the light weight of the OTA, I was pretty sure I would be able to use it and not have to upgrade to a Losmandy “D” setup.

First Light…

At mid-afternoon, the sky was not looking good, not good at all, which wasn’t a surprise given the sort of weather we’d had over the past month. But as the day wound down it suddenly became apparent there would be some clearing. By sundown, the sky overhead was looking better and better, though glancing at the horizon showed more bad-stuff clearly on the way. Speed was clearly of the essence, so I didn’t fool with the CGEM, assembling the VX instead.

Even before aligning the VX, I could tell the mount was going to be happy with the refractor. While the longer tube of this 11.3-pound OTA maybe put a little more stress on the GEM than my 14-pound Edge 800 with its short tube does, it was clearly not more than the VX could handle. It only took one 11-pound Synta pancake weight to balance the mount with the, 2-inch diagonal, and one of my (heavy) Ethos eyepieces.

With clouds beginning to flow back in as astronomical twilight came on, I didn’t waste time doing a precise polar alignment. Sighted Polaris in the hollow polar bore, did a 2+4 goto alignment, and we were off to the races with our first light object. Which was? Vega. No point in delaying; I wanted to know from the start what the excess color situation would be with this big refractor. What I saw was truly astounding:  in focus Vega was a pure white. On either side of focus, there was a tinge, but just a faint tinge of color. In focus, nada, zip, zilch. Hooray!

How was the mount’s operation with the refractor onboard? Even with the legs extended about 75% to allow me to comfortably view objects overhead (while seated in my observing chair), the shakes were minimal. Goto operation was normal with no hesitation of funky sounds from the mount. For visual, at least, the VX plus the Pro 120ED is a fine combo.

That was almost all I was able to accomplish on night one. Oh, I did scope out M15, M37, NGC 457, and a few other bright objects as haze and clouds built. How did they look? Pretty putrid in the poor conditions, but they still looked like star clusters should look in a good refractor: tiny stars even at 200x. How was field flatness? At f/7.5, very good. My higher quality eyepieces presented beautiful views field edge to field edge, and even my old Happy Hand Grenade 16mm Zhumell 100-degree did a reasonable job, similar to what it does in the Edge 800.

I was hoping to get a look at M42 on this first light night, but that was clearly not going to happen. It was obvious that by the time it was above the trees to the east we’d be completely socked in again. There was time for one more test. I inserted a heavyweight eyepiece, my 35mm Panoptic, sent the scope to an object nearly at the zenith, and did some experimenting with the focuser.

Not too bad, but there was some slippage with the big ocular. It was clear I’d need to adjust the Crayford if it were to handle my DSLRs and field flattener. That would be in the morning, though. The stars were winking out now, and I called it a night. I left the mount out in the yard (covered), but I brought the 120 inside. I just couldn’t bear to leave beautiful new baby out in the yard all by herself.

Adjusting the focuser proved to be fairly simple. Next morning, I mounted the OTA back on the VX, installed my Canon 400D and Hotech field flattener, and pointed the scope to the zenith. Using instructions I found on the Internet, I adjusted one hex screw on the focuser until the Crayford held the load of the DSLR and flattener with no slipping, but remained reasonably easy to focus with the coarse control.

The Naming of Telescopes…

Sometimes you do get thrown a bone. The Saturday night after receiving the 120, the Moon was old and the clouds were gone for a while. I headed to our club dark observing site about 30-minutes to the west. It’s not pitch black dark, but the Milky Way is easy on any halfway decent night and I thought that if the weather held I might have a chance to see what the new telescope could really do.

I actually did get that chance, though my two fellow club members, Taras and Ken, and I were only given a little over two hours of good conditions. The Milky Way was visible, but only faintly visible and then only for the first hour of darkness.  Still, that was enough time for the new girl, again set up on the VX—this would be a purely visual night—to show her mettle.

First object after astronomical twilight was the great globular cluster in Aquarius, M2. In my opinion, this beauty is one of the most overlooked globs in the sky. Maybe because it’s a trifle low for our northern brothers and sisters. All I know was that it was a wonder in the refractor, even at 30x, and the more I increased the magnification, the better it looked.

I topped out at just under 200x with my new Explore Scientific 4.7 mm 82-degree eyepiece (didn’t bring a Barlow), and M2 was simply stupendous at that magnification with tiny stars and plenty of resolution across its face. I really didn’t think its appearance was much different from what it is in an 8-inch—and I’ve viewed this one countless times with my C8s. Well, except maybe that the stars were tighter in the refractor. Heck, my two buddies and I didn’t think the view under these conditions was that much worse than what it was in Taras' 15-inch Dobsonian.

That was pretty much the story with everything I observed. Very similar, all in all, to what I’d have seen in an 8-inch, but with that refractor zip added. What didn’t I get to try? The Moon or a planet. The Moon didn’t rise till long after the clouds intruded, and there were no evening planets on hand. Given the way the scope handles bright stars, however, I have little doubt she will be good on the Solar System.

Most surprising DSO of the night? Had to be the Helix Nebula. I wasn’t expecting a heck of a lot out of NGC 7293. The big planetary was low and on the outskirts of the Mobile, Alabama light-dome. I sent the VX that way anyway, inserting my 30mm “finding” eyepiece, an el-cheapo GSO that came with my 10-inch Dobsonian. Why I did that, I don’t know. Such a low power, 30x, would surely render the big nebula invisible in the sky glow.

Nope. Even at that low magnification and with the resulting bright background, the nebula was still visible as a round spot at field center. That is testament, I think, to the superior contrast characteristics of a good refractor. I didn’t mess around at low power long, replacing the 30mm with my 13mm Ethos and affixing an OIII filter to that.

At 70x, the Helix was starkly visible. While the donut hole was not easy, it was there. Bumping up to 112X with the 8mm Ethos further improved the view, and, as I continued to stare, I began to pick up the arc of nebulosity outside the main annulus. What it reminded me of was the way the Helix looked with a C8/OIII years ago at the old Deep South Regional Star Gaze at Percy Quin State Park near McComb, Mississippi, where the skies were considerably better than what I had on this night. All I knew was that what I was seeing was marvelous, and proved to me that a 5-inch refractor can be a satisfying visual instrument for the deep sky.

So it went for a while longer, till haze began to drift in in advance of the next storm front and we called it. I was just thrilled. The views provided by the new scope were everything I’d hoped for. The concern I’d had about the focuser had also evaporated. Oh, someday I may still replace it with a Moonlite, but over the course of the evening I didn’t have any problems with it and didn’t even give it any thought—it just worked.

Only one thing was left. The naming. While I have often told you, dear readers, that you should look upon telescopes as tools, there is no denying I don’t always practice what I preach. In spite of myself, my telescopes inevitably become more than just tools. They become my friends with individual quirks and personalities, and I have to give them names. At the end of this evening, the SkyWatcher's name was obvious; I didn’t even have to think about it. Folks, meet Hermione (Granger). “Herminone” because she is clearly magic.

The Final Test…

There was no doubt after my dark site run that Hermione would get some use as a visual scope, but that was not why I bought her. I have an excellent 10-inch Dobbie for visual. The main impetus behind acquiring a 5-inch APO was to have an imaging scope with a little more aperture and focal length than my smaller APOs, but less focal length than my Edge 800 (which comes in at 1400 mm with a reducer). So, I wanted to give Miss H. a clean bill of health imaging-wise as soon as possible. That happened just as the Moon was coming back into the sky, but before the wave of pre-Christmas storms that are still plaguing the Gulf Coast began to roll through.

Actually, I had little doubt Hermione acquit herself well for imaging. My main concern was with the whole package, scope and CGEM. I had yet to try to auto-guide the Celestron mount in the months since I got her. The main reason for that being the terrible summer and autumn weather, of course. It’s been bad, and the two major imaging expeditions I did this year, one to the Deep South Regional Star Gaze, and one to the Peach State Star Gaze, involved targets well suited to my 80mm APO, which is just fine on the VX—a lot easier to haul around than a CGEM.

Wouldn’t you know it, though? By the time the mount and Hermione were set up (I used an ADM Vixen-to-Losmandy adapter to get the 120 on the CGEM), the sky was going south again. That meant I was not able to spend any time tweaking the settings in PHD2. I went with the stock settings in the brain icon, firing off 20 2-minute exposures of M15. I believe I could have gone longer than 2-minutes per sub with PHD2, but the background was bright enough in 120-second frames that I didn’t dare expose longer. Building haze was making my normal light pollution worse, scattering the glow from the subdivision’s countless Christmas lights till the sky was a near Technicolor mess. At any rate, the stars were perfectly round in every sub. The only ones I threw out were a few where drifting clouds had passed through the field.

My thoughts on the results shown here? Darned good considering the conditions. If I ever get another clear night, I’ll tweak PHD2, but given my modest requirements, I’d say guiding was good enough as is. Certainly it was a lot easier to image with the refractor than with my focal-reduced C8. Any light pollution induced gradients were minor and not like the “porthole” effect I get with the Edge and its f/7 reducer under these conditions. While the Edge displays minimal focus shift, it was also nice to be using a scope with none.

What’s next other than tuning up PHD2 a little in the backyard? Some dark-site imaging time should el Niño have mercy on me. Accessories? Now that I have resolved to continue with the stock focuser, for a while, anyway, I might consider the SkyWatcher .8x reducer/flattener. However, at this time, I’m pretty happy with the image scale the scope produces at f/7.5. A little faster would be nice, sure, but “a little faster” would mean “a little smaller” in the frame, and 900mm is well suited to the sorts of objects I photograph. If I need more field, there is always one of my smaller APOs, and flattening wise, the Hotech is doing one heck of a job.

Will I miss Betsy sometimes? I will. Mostly because of the wonderful memories. But I still have those memories, and I still have my C11, Bertha, and Zelda, my 10-inch Zhumell Dobsonian, who is a lot easier to handle than Bets ever was. As for the vaunted Hermione Granger? I believe this is the beginning of a beautiful friendship.




Comments:
Looks like a success to me, although 21 years is a long run with a trusty telescope i'm sure you'll have many more with the new one
 
Are you using a StarSense on your new Refractor? You do realise your refractor is 4.7" and not 5"?

Dave Aucoin
 
Yes I am using a StarSense, Dave. And yes, I did figure out that 120mm is a few millimeters short of 5 inches. That's why I said I decided to settle for "a little less than 5-inches." ;)
 
Hi Rod,

I have the 100 mm Pro ED on backorder since December, supposedly due in mid-February. We'll see. Since I already have a 12.5 Truss, and an older 6" f/8 Astrophysics (mid-1980s), I wanted a 4" class refractor for quick trips outdoors. Also, I bought it with the 2017 eclipse in mind, since that trip will hopefully involve dark moon stargazing somewhere in the vicinity of the eclipse path, but with the need for “rapid deployment” should clouds have to be dodged. (Also, couldn't pass up the sale...) Enjoy your 120!

John O'Hara
NW Pennsylvania

 
I'm interested in the 120 but noticed from forums that you can't collimate the objective like you can with the ES 127 scope. Do you see that as a problem? I'm assuming that if i check out the collimation when I get it, and send it back if it's our, then I shouldn't have to worry about it any more, assuming I don't drop kick it during transportation to and from the field! Your thoughts?

 
I don't think so. Quite robust mechanically, and I haven't heard anyone having problems with collimation.
 
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